Publications by authors named "Justyna A Karolak"

36 Publications

Changes in Nuclear Gene Expression Related to Mitochondrial Function Affect Extracellular Matrix, Collagens, and Focal Adhesion in Keratoconus.

Transl Vis Sci Technol 2021 Sep;10(11)

Chair and Department of Genetics and Pharmaceutical Microbiology, Poznan University of Medical Sciences, Poznan, Poland.

Purpose: Mitochondrial DNA (mtDNA) abnormalities were previously found to be causative in the pathogenesis of various diseases. Here, comprehensive mitochondrial and nuclear sequence and transcript analyses, along with analyses of the methylation aspects of nuclear genes related to mitochondrial function, were performed in patients with keratoconus (KTCN) to evaluate their contribution to the KTCN pathogenesis.

Methods: Blood mtDNA of 42 KTCN and 51 non-KTCN individuals was Sanger sequenced and analyzed along with the previously obtained corneal RNA-sequencing data of 20 KTCN and 21 non-KTCN individuals. In addition, the expression and methylation of mtDNA genes and 1223 mitochondria-related nuclear genes were evaluated.

Results: The mtDNA sequence alterations detected in blood coincided with variants identified in transcripts of the matched corneal tissues. In KTCN corneas, 97 mitochondria-related genes were deregulated, including TGFB1, P4HB, and BCL2, which are involved in the extracellular matrix (ECM) organization, collagen formation, and focal adhesion pathways. No changes in the expression of mtDNA transcripts and no differentially methylated genes among the assessed mitochondrial-nuclear gene sets were found.

Conclusions: The absence of corneal-specific mtDNA variants indicates that there is no direct relationship between mitochondrial sequence variability and KTCN phenotype in the studied individuals. However, the identified KTCN-specific transcriptomic alterations of the nuclear genes directly related to the mitochondria functioning point to their possible involvement in the ECM organization, collagen formation, and focal adhesion.

Translational Relevance: The identification of abnormalities within nuclear genes regulating ECM formation, collagen synthesis, and/or focal adhesion may form the basis of future treatment strategies or predict the progression of corneal changes in KTCN.
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http://dx.doi.org/10.1167/tvst.10.11.6DOI Listing
September 2021

Perturbation of semaphorin and VEGF signaling in ACDMPV lungs due to FOXF1 deficiency.

Respir Res 2021 Jul 27;22(1):212. Epub 2021 Jul 27.

Department of Molecular and Human Genetics, Baylor College of Medicine, One Baylor Plaza, Rm ABBR-R809, Houston, TX, 77030, USA.

Background: Alveolar capillary dysplasia with misalignment of pulmonary veins (ACDMPV) is a rare lethal congenital lung disorder in neonates characterized by severe progressive respiratory failure and refractory pulmonary hypertension, resulting from underdevelopment of the peripheral pulmonary tree. Causative heterozygous single nucleotide variants (SNVs) or copy-number variant (CNV) deletions involving FOXF1 or its distant lung-specific enhancer on chromosome 16q24.1 have been identified in 80-90% of ACDMPV patients. FOXF1 maps closely to and regulates the oppositely oriented FENDRR, with which it also shares regulatory elements.

Methods: To better understand the transcriptional networks downstream of FOXF1 that are relevant for lung organogenesis, using RNA-seq, we have examined lung transcriptomes in 12 histopathologically verified ACDMPV patients with or without pathogenic variants in the FOXF1 locus and analyzed gene expression profile in FENDRR-depleted fetal lung fibroblasts, IMR-90.

Results: RNA-seq analyses in ACDMPV neonates revealed changes in the expression of several genes, including semaphorins (SEMAs), neuropilin 1 (NRP1), and plexins (PLXNs), essential for both epithelial branching and vascular patterning. In addition, we have found deregulation of the vascular endothelial growth factor (VEGF) signaling that also controls pulmonary vasculogenesis and a lung-specific endothelial gene TMEM100 known to be essential in vascular morphogenesis. Interestingly, we have observed a substantial difference in gene expression profiles between the ACDMPV samples with different types of FOXF1 defect. Moreover, partial overlap between transcriptome profiles of ACDMPV lungs with FOXF1 SNVs and FENDRR-depleted IMR-90 cells suggests contribution of FENDRR to ACDMPV etiology.

Conclusions: Our transcriptomic data imply potential crosstalk between several lung developmental pathways, including interactions between FOXF1-SHH and SEMA-NRP or VEGF/VEGFR2 signaling, and provide further insight into complexity of lung organogenesis in humans.
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http://dx.doi.org/10.1186/s12931-021-01797-7DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC8314029PMC
July 2021

Influence of , , , and Knockdowns on CTGF, TGFBR2, and DNMT3A in Neonatal and Adult Human Dermal Fibroblasts Cell Lines.

Curr Issues Mol Biol 2021 Jun 3;43(1):276-285. Epub 2021 Jun 3.

Chair and Department of Genetics and Pharmaceutical Microbiology, Poznan University of Medical Sciences, 60-781 Poznan, Poland.

Dermal fibroblasts are responsible for the production of the extracellular matrix that undergoes significant changes during the skin aging process. These changes are partially controlled by the TGF-β signaling, which regulates tissue homeostasis dependently on several genes, including CTGF and DNA methyltransferases. To investigate the potential differences in the regulation of the TGF-β signaling and related molecular pathways at distinct developmental stages, we silenced the expression of , , , , , and in the neonatal (HDF-N) and adult (HDF-A) human dermal fibroblasts using the RNAi method. Through Western blot, we analyzed the effects of the knockdowns of these genes on the level of the CTGF, TGFBR2, and DNMT3A proteins in both cell lines. In the assays, we observed that CTGF level was decreased after knockdown of in HDF-N but not in HDF-A. Similarly, the level of DNMT3A was decreased only in HDF-N after silencing of , or . TGFBR2 level was lower in HDF-N after knockdown of , , or but it was higher in HDF-A after TGFB1 silencing. The reduction of TGFBR2 after silencing of and vice versa in neonatal cells only suggests the developmental stage-specific interactions between these two genes. However, additional studies are needed to explain the dependencies between analyzed proteins.
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http://dx.doi.org/10.3390/cimb43010023DOI Listing
June 2021

Characterization of Ocular Surface Microbial Profiles Revealed Discrepancies between Conjunctival and Corneal Microbiota.

Pathogens 2021 Mar 30;10(4). Epub 2021 Mar 30.

Chair and Department of Genetics and Pharmaceutical Microbiology, Poznan University of Medical Sciences, 60-781 Poznan, Poland.

The ocular microbiome composition has only been partially characterized. Here, we used RNA-sequencing (RNA-Seq) data to assess microbial diversity in human corneal tissue. Additionally, conjunctival swab samples were examined to characterize ocular surface microbiota. Short RNA-Seq reads, obtained from a previous transcriptome study of 50 corneal tissues, were mapped to the human reference genome GRCh38 to remove sequences of human origin. The unmapped reads were then used for taxonomic classification by comparing them with known bacterial, archaeal, and viral sequences from public databases. The components of microbial communities were identified and characterized using both conventional microbiology and polymerase chain reaction (PCR) techniques in 36 conjunctival swabs. The majority of ocular samples examined by conventional and molecular techniques showed very similar microbial taxonomic profiles, with most of the microorganisms being classified into , , and phyla. Only 50% of conjunctival samples exhibited bacterial growth. The PCR detection provided a broader overview of positive results for conjunctival materials. The RNA-Seq assessment revealed significant variability of the corneal microbial communities, including fastidious bacteria and viruses. The use of the combined techniques allowed for a comprehensive characterization of the eye microbiome's elements, especially in aspects of microbiota diversity.
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http://dx.doi.org/10.3390/pathogens10040405DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC8067172PMC
March 2021

Lung-specific distant enhancer cis regulates expression of FOXF1 and lncRNA FENDRR.

Hum Mutat 2021 Jun 6;42(6):694-698. Epub 2021 Apr 6.

Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, Texas, USA.

The FOXF1 gene, causative for a neonatal lethal lung developmental disorder alveolar capillary dysplasia with misalignment of pulmonary veins (ACDMPV), maps 1.7 kb away from the long noncoding RNA gene FENDRR on the opposite strand, suggesting they may be coregulated. Using RNA sequencing in lung tissue from ACDMPV patients with heterozygous deletions of the FOXF1 distant enhancer located 286 kb upstream, leaving FOXF1 and FENDRR intact, we have found that the FENDRR and FOXF1 expressions were reduced by approximately 75% and 50%, respectively, and were monoallelic from the intact chromosome 16q24.1. In contrast, ACDMPV patients with FOXF1 SNVs had biallelic FENDRR expression reduced by 66%-82%. Corroboratively, depletion of FOXF1 by small interfering RNA in lung fibroblasts resulted in a 50% decrease of FENDRR expression. These data indicate that FENDRR expression in the lungs is regulated both in cis by the FOXF1 distant enhancer and in trans by FOXF1. Our findings are compatible with the involvement of FENDRR in FOXF1-related disorders, including ACDMPV.
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http://dx.doi.org/10.1002/humu.24198DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC8284783PMC
June 2021

Variants in FLRT3 and SLC35E2B identified using exome sequencing in seven high myopia families from Central Europe.

Adv Med Sci 2021 Mar 9;66(1):192-198. Epub 2021 Mar 9.

Institute of Human Genetics, Polish Academy of Sciences, Poznan, Poland; Chair and Department of Genetics and Pharmaceutical Microbiology, Poznan University of Medical Sciences, Poznan, Poland. Electronic address:

Purpose: High myopia (HM) is an eye disorder with both environmental and genetic factors involved. Many genetic factors responsible for HM were recognized worldwide, but little is known about genetic variants underlying HM in Central Europe. Thus, the aim of this study was to identify rare sequence variants involved in HM in families from Central Europe to better understand the genetic basis of HM.

Materials And Methods: We assessed 17 individuals from 7 unrelated Central European families with hereditary HM using exome sequencing (ES). Segregation of selected variants in other available family members was performed using Sanger sequencing.

Results: Detected 73 rare variants were selected for verification. We observed 2 missense variants, c.938C>T in SLC35E2B - encoding solute carrier family 35 member E2B, and c.1642G>C in FLRT3 - encoding fibronectin leucine rich transmembrane protein, segregating with HM in one family.

Conclusions: FLRT3 ​and/or ​SLC35E2B ​could represent disease candidate genes and identified sequence variants might be responsible for HM in the studied family.
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http://dx.doi.org/10.1016/j.advms.2021.02.005DOI Listing
March 2021

Potential interactions between the TBX4-FGF10 and SHH-FOXF1 signaling during human lung development revealed using ChIP-seq.

Respir Res 2021 Jan 21;22(1):26. Epub 2021 Jan 21.

Department of Molecular & Human Genetics, Baylor College of Medicine, One Baylor Plaza, Rm ABBR-R809, Houston, TX, 77030, USA.

Background: The epithelial-mesenchymal signaling involving SHH-FOXF1, TBX4-FGF10, and TBX2 pathways is an essential transcriptional network operating during early lung organogenesis. However, precise regulatory interactions between different genes and proteins in this pathway are incompletely understood.

Methods: To identify TBX2 and TBX4 genome-wide binding sites, we performed chromatin immunoprecipitation followed by next-generation sequencing (ChIP-seq) in human fetal lung fibroblasts IMR-90.

Results: We identified 14,322 and 1,862 sites strongly-enriched for binding of TBX2 and TBX4, respectively, 43.95% and 18.79% of which are located in the gene promoter regions. Gene Ontology, pathway enrichment, and DNA binding motif analyses revealed a number of overrepresented cues and transcription factor binding motifs relevant for lung branching that can be transcriptionally regulated by TBX2 and/or TBX4. In addition, TBX2 and TBX4 binding sites were found enriched around and within FOXF1 and its antisense long noncoding RNA FENDRR, indicating that the TBX4-FGF10 cascade may directly interact with the SHH-FOXF1 signaling.

Conclusions: We highlight the complexity of transcriptional network driven by TBX2 and TBX4 and show that disruption of this crosstalk during morphogenesis can play a substantial role in etiology of lung developmental disorders.
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http://dx.doi.org/10.1186/s12931-021-01617-yDOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7818749PMC
January 2021

Further evaluation of differential expression of keratoconus candidate genes in human corneas.

PeerJ 2020 20;8:e9793. Epub 2020 Aug 20.

Chair and Department of Genetics and Pharmaceutical Microbiology, Poznan University of Medical Sciences, Poznan, Poland.

Background: Keratoconus (KTCN) is a progressive eye disease, characterized by changes in the shape and thickness of the cornea that results in loss of visual acuity. While numerous KTCN candidate genes have been identified, the genetic etiology of the disease remains undetermined. To further investigate and verify the contribution of particular genetic factors to KTCN, we assessed 45 candidate genes previously indicated as involved in KTCN etiology based on transcriptomic and genomic data.

Methods: The RealTime ready Custom Panel, covering 45 KTCN candidate genes and two reference transcripts, has been designed. Then, the expression profiles have been assessed using the RT-qPCR assay in six KTCN and six non-KTCN human corneas, obtained from individuals undergoing a penetrating keratoplasty procedure.

Results: In total, 35 genes exhibiting differential expression between KTCN and non-KTCN corneas have been identified. Among these genes were ones linked to the extracellular matrix formation, including collagen synthesis or the TGF-β, Hippo, and Wnt signaling pathways. The most downregulated transcripts in KTCN corneas were , and , while and were the most upregulated ones. Hierarchical clustering of expression profiles demonstrated almost clear separation between KTCN and non-KTCN corneas. The gene expression levels determined using RT-qPCR showed a strong correlation with previous RNA sequencing (RNA-Seq) results.

Conclusions: A strong correlation between RT-qPCR and earlier RNA-Seq data confirms the possible involvement of genes from collagen synthesis and the TGF-β, Hippo, and Wnt signaling pathways in KTCN etiology. Our data also revealed altered expression of several genes, such as , , and , in which single nucleotide variants have been frequently identified in KTCN. These findings further highlight the heterogeneous nature of KTCN.
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http://dx.doi.org/10.7717/peerj.9793DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7443321PMC
August 2020

Low-level parental somatic mosaic SNVs in exomes from a large cohort of trios with diverse suspected Mendelian conditions.

Genet Med 2020 11 13;22(11):1768-1776. Epub 2020 Jul 13.

Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, TX, USA.

Purpose: The goal of this study was to assess the scale of low-level parental mosaicism in exome sequencing (ES) databases.

Methods: We analyzed approximately 2000 family trio ES data sets from the Baylor-Hopkins Center for Mendelian Genomics (BHCMG) and Baylor Genetics (BG). Among apparent de novo single-nucleotide variants identified in the affected probands, we selected rare unique variants with variant allele fraction (VAF) between 30% and 70% in the probands and lower than 10% in one of the parents.

Results: Of 102 candidate mosaic variants validated using amplicon-based next-generation sequencing, droplet digital polymerase chain reaction, or blocker displacement amplification, 27 (26.4%) were confirmed to be low- (VAF between 1% and 10%) or very low (VAF <1%) level mosaic. Detection precision in parental samples with two or more alternate reads was 63.6% (BHCMG) and 43.6% (BG). In nine investigated individuals, we observed variability of mosaic ratios among blood, saliva, fibroblast, buccal, hair, and urine samples.

Conclusion: Our computational pipeline enables robust discrimination between true and false positive candidate mosaic variants and efficient detection of low-level mosaicism in ES samples. We confirm that the presence of two or more alternate reads in the parental sample is a reliable predictor of low-level parental somatic mosaicism.
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http://dx.doi.org/10.1038/s41436-020-0897-zDOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7606563PMC
November 2020

Genotype-phenotype correlation in two Polish neonates with alveolar capillary dysplasia.

BMC Pediatr 2020 06 29;20(1):320. Epub 2020 Jun 29.

Department of Neonatology, Neonatal Biophysical Monitoring and Cardiopulmonary Therapies Research Unit, Poznan University of Medical Sciences, Poznan, Poland.

Background: Alveolar capillary dysplasia (ACD) is a rare cause of severe pulmonary hypertension and respiratory failure in neonates. The onset of ACD is usually preceded by a short asymptomatic period. The condition is refractory to all available therapies as it irreversibly affects development of the capillary bed in the lungs. The diagnosis of ACD is based on histopathological evaluation of lung biopsy or autopsy tissue or genetic testing of FOXF1 on chromosome 16q24.1. Here, we describe the first two Polish patients with ACD confirmed by histopathological and genetic examination.

Case Presentation: The patients were term neonates with high Apgar scores in the first minutes of life. They both were diagnosed prenatally with heart defects. Additionally, the first patient presented with omphalocele. The neonate slightly deteriorated around 12 hour of life, but underwent surgical repair of omphalocele followed by mechanical ventilation. Due to further deterioration, therapy included inhaled nitric oxide (iNO), inotropes and surfactant administration. The second patient was treated with prostaglandin E1 since birth due to suspicion of aortic coarctation (CoA). After ruling out CoA in the 3 day of life, infusion of prostaglandin E1 was discountinued and immediately patient's condition worsened. Subsequent treatment included re-administration of prostaglandin E1, iNO and mechanical ventilation. Both patients presented with transient improvement after application of iNO, but died despite maximized therapy. They were histopathologically diagnosed post-mortem with ACD. Array comparative genomic hybridization in patient one and patient two revealed copy-number variant (CNV) deletions, respectively, ~ 1.45 Mb in size involving FOXF1 and an ~ 0.7 Mb in size involving FOXF1 enhancer and leaving FOXF1 intact.

Conclusions: Both patients presented with a distinct course of ACD, extra-pulmonary manifestations and response to medications. Surgery and ceasing of prostaglandin E1 infusion should be considered as potential causes of this variability. We further highlight the necessity of thorough genetic testing and histopathological examination and propose immunostaining for CD31 and CD34 to facilitate the diagnostic process for better management of infants with ACD.
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http://dx.doi.org/10.1186/s12887-020-02200-yDOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7322906PMC
June 2020

Parental somatic mosaicism for CNV deletions - A need for more sensitive and precise detection methods in clinical diagnostics settings.

Genomics 2020 09 6;112(5):2937-2941. Epub 2020 May 6.

Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, TX 77030, USA. Electronic address:

To further assess the scale and level of parental somatic mosaicism, we queried the CMA database at Baylor Genetics. We selected 50 unrelated families where clinically relevant apparent de novo CNV-deletions were found in the affected probands. Parental blood samples screening using deletion junction-specific PCR revealed four parents with somatic mosaicism. Droplet digital PCR (ddPCR), qPCR, and amplicon-based next-generation sequencing (NGS) were applied to validate these findings. Using ddPCR levels of mosaicism ranged from undetectable to 18.5%. Amplicon-based NGS and qPCR for the father with undetectable mosaicism was able to detect mosaicism at 0.39%. In one mother, ddPCR analysis revealed 15.6%, 10.6%, 8.2%, and undetectable levels of mosaicism in her blood, buccal cells, saliva, and urine samples, respectively. Our data suggest that more sensitive and precise methods, e.g. CNV junction-specific LR-PCR, ddPCR, or qPCR may allow for a more refined assessment of the potential disease recurrence risk for an identified variant.
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http://dx.doi.org/10.1016/j.ygeno.2020.05.003DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7363577PMC
September 2020

Accumulation of sequence variants in genes of Wnt signaling and focal adhesion pathways in human corneas further explains their involvement in keratoconus.

PeerJ 2020 14;8:e8982. Epub 2020 Apr 14.

Chair and Department of Genetics and Pharmaceutical Microbiology, Poznan University of Medical Sciences, Poznan, Poland.

Background: Keratoconus (KTCN) is a protrusion and thinning of the cornea, resulting in loss of visual acuity. The etiology of KTCN remains unclear. The purpose of this study was to assess the potential involvement of new genetic variants in KTCN etiology based on both the genomic and transcriptomic findings recognized in the same corneal tissues.

Methods: Corneal tissues derived from five unrelated Polish individuals with KTCN were examined using exome sequencing (ES), followed by enrichment analyses. For comparison purposes, the datasets comprising ES data of five randomly selected Polish individuals without ocular abnormalities and five Polish patients with high myopia were used. Expression levels of selected genes from the overrepresented pathways were obtained from the previous RNA-Seq study.

Results: Exome capture discovered 117 potentially relevant variants that were further narrowed by gene overrepresentation analyses. In each of five patients, the assessment of functional interactions revealed rare (MAF ≤ 0.01) DNA variants in at least one gene from Wnt signaling (, , , , ) and focal adhesion (, , , , ) pathways. No genes involved in pathways enriched in KTCN corneas were overrepresented in our control sample sets.

Conclusions: The results of this first pilot ES profiling of human KTCN corneas emphasized that accumulation of sequence variants in several genes from Wnt signaling and/or focal adhesion pathways might cause the phenotypic effect and further points to a complex etiology of KTCN.
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http://dx.doi.org/10.7717/peerj.8982DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7164425PMC
April 2020

A de novo 2.2 Mb recurrent 17q23.1q23.2 deletion unmasks novel putative regulatory non-coding SNVs associated with lethal lung hypoplasia and pulmonary hypertension: a case report.

BMC Med Genomics 2020 03 6;13(1):34. Epub 2020 Mar 6.

Department of Molecular & Human Genetics, Baylor College of Medicine, Houston, TX, 77030, USA.

Background: Application of whole genome sequencing (WGS) enables identification of non-coding variants that play a phenotype-modifying role and are undetectable by exome sequencing. Recently, non-coding regulatory single nucleotide variants (SNVs) have been reported in patients with lethal lung developmental disorders (LLDDs) or congenital scoliosis with recurrent copy-number variant (CNV) deletions at 17q23.1q23.2 or 16p11.2, respectively.

Case Presentation: Here, we report a deceased newborn with pulmonary hypertension and pulmonary interstitial emphysema with features suggestive of pulmonary hypoplasia, resulting in respiratory failure and neonatal death soon after birth. Using the array comparative genomic hybridization and WGS, two heterozygous recurrent CNV deletions: ~ 2.2 Mb on 17q23.1q23.2, involving TBX4, and ~ 600 kb on 16p11.2, involving TBX6, that both arose de novo on maternal chromosomes were identified. In the predicted lung-specific enhancer upstream to TBX4, we have detected seven novel putative regulatory non-coding SNVs that were absent in 13 control individuals with the overlapping deletions but without any structural lung anomalies.

Conclusions: Our findings further support a recently reported model of complex compound inheritance of LLDD in which both non-coding and coding heterozygous TBX4 variants contribute to the lung phenotype. In addition, this is the first report of a patient with combined de novo heterozygous recurrent 17q23.1q23.2 and 16p11.2 CNV deletions.
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http://dx.doi.org/10.1186/s12920-020-0701-6DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7060516PMC
March 2020

Highly Sensitive Blocker Displacement Amplification and Droplet Digital PCR Reveal Low-Level Parental FOXF1 Somatic Mosaicism in Families with Alveolar Capillary Dysplasia with Misalignment of Pulmonary Veins.

J Mol Diagn 2020 04 7;22(4):447-456. Epub 2020 Feb 7.

Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, Texas. Electronic address:

Detection of low-level somatic mosaicism [alternate allele fraction (AAF) ≤ 10%] in parents of affected individuals with the apparent de novo pathogenic variants enables more accurate estimate of recurrence risk. To date, only a few systematic analyses of low-level parental somatic mosaicism have been performed. Herein, highly sensitive blocker displacement amplification, droplet digital PCR, quantitative PCR, long-range PCR, and array comparative genomic hybridization were applied in families with alveolar capillary dysplasia with misalignment of pulmonary veins. We screened 18 unrelated families with the FOXF1 variant previously determined to be apparent de novo (n = 14), of unknown parental origin (n = 1), or inherited from a parent suspected to be somatic and/or germline mosaic (n = 3). We identified four (22%) families with FOXF1 parental somatic mosaic single-nucleotide variants (n = 3) and copy number variant deletion (n = 1) detected in parental blood samples and an AAF ranging between 0.03% and 19%. In one family, mosaic allele ratio in tissues originating from three germ layers ranged between <0.03% and 0.65%. Because the ratio of parental somatic mosaicism have significant implications for the recurrence risk, this study further implies the importance of a systematic screening of parental samples for low-level and very-low-level (AAF ≤ 1%) somatic mosaicism using methods that are more sensitive than those routinely applied in diagnostics.
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http://dx.doi.org/10.1016/j.jmoldx.2019.12.007DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7193866PMC
April 2020

Association of rare non-coding SNVs in the lung-specific FOXF1 enhancer with a mitigation of the lethal ACDMPV phenotype.

Hum Genet 2019 Dec 4;138(11-12):1301-1311. Epub 2019 Nov 4.

Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, TX, USA.

Haploinsufficiency of FOXF1 causes alveolar capillary dysplasia with misalignment of pulmonary veins (ACDMPV), a lethal neonatal lung developmental disorder. We describe two similar heterozygous CNV deletions involving the FOXF1 enhancer and re-analyze FOXF1 missense mutation, all associated with an unexpectedly mitigated disease phenotype. In one case, the deletion of the maternal allele of the FOXF1 enhancer caused pulmonary hypertension and histopathologically diagnosed MPV without the typical ACD features. In the second case, the deletion of the paternal enhancer resulted in ACDMPV rather than the expected neonatal lethality. In both cases, FOXF1 expression in lung tissue was higher than usually seen or expected in patients with similar deletions, suggesting an increased activity of the remaining allele of the enhancer. Sequencing of these alleles revealed two rare SNVs, rs150502618-A and rs79301423-T, mapping to the partially overlapping binding sites for TFAP2s and CTCF in the core region of the enhancer. Moreover, in a family with three histopathologically-diagnosed ACDMPV siblings whose missense FOXF1 mutation was inherited from the healthy non-mosaic carrier mother, we have identified a rare SNV rs28571077-A within 2-kb of the above-mentioned non-coding SNVs in the FOXF1 enhancer in the mother, that was absent in the affected newborns and 13 unrelated ACDMPV patients with CNV deletions of this genomic region. Based on the low population frequencies of these three variants, their absence in ACDMPV patients, the results of reporter assay, RNAi and EMSA experiments, and in silico predictions, we propose that the described SNVs might have acted on FOXF1 enhancer as hypermorphs.
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http://dx.doi.org/10.1007/s00439-019-02073-xDOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6874894PMC
December 2019

A recurrent 8 bp frameshifting indel in FOXF1 defines a novel mutation hotspot associated with alveolar capillary dysplasia with misalignment of pulmonary veins.

Am J Med Genet A 2019 11 22;179(11):2272-2276. Epub 2019 Aug 22.

Department of Molecular & Human Genetics, Baylor College of Medicine, Houston, Texas.

Alveolar capillary dysplasia with misalignment of pulmonary veins (ACDMPV) is a rare lethal lung developmental disease. Affected infants manifest with severe respiratory distress and refractory pulmonary hypertension and uniformly die in the first month of life. Heterozygous point mutations or copy-number variant deletions involving FOXF1 and/or its upstream lung-specific enhancer on 16q24.1 have been identified in the vast majority of ACDMPV patients. We have previously described two unrelated families with a de novo pathogenic frameshift variant c.691_698del (p.Ala231Argfs*61) in the exon 1 of FOXF1. Here, we present a third unrelated ACDMPV family with the same de novo variant and propose that a direct tandem repeat of eight consecutive nucleotides GCGGCGGC within the ~4 kb CpG island in FOXF1 exon 1 is a novel mutation hotspot causative for ACDMPV.
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http://dx.doi.org/10.1002/ajmg.a.61338DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6849398PMC
November 2019

Heterozygous CTNNB1 and TBX4 variants in a patient with abnormal lung growth, pulmonary hypertension, microcephaly, and spasticity.

Clin Genet 2019 10 22;96(4):366-370. Epub 2019 Jul 22.

Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, Texas.

The canonical wingless (Wnt) and fibroblast growth factor (FGF) signaling pathways involving CTNNB1 and TBX4, respectively, are crucial for the regulation of human development. Perturbations of these pathways and disruptions from biological homeostasis have been associated with abnormal morphogenesis of multiple organs, including the lung. The aim of this study was to identify the underlying genetic cause of abnormal lung growth, pulmonary hypertension (PAH), severe microcephaly, and muscle spasticity in a full-term newborn, who died at 4 months of age due to progressively worsening PAH and respiratory failure. Family trio exome sequencing showed a de novo heterozygous nonsense c.1603C>T (p.Arg535*) variant in CTNNB1 and a paternally inherited heterozygous missense c.1198G>A (p.Glu400Lys) variant in TBX4, both predicted to be likely deleterious. We expand the phenotypic spectrum associated with CTNNB1 and TBX4 variants and indicate that they could act synergistically to produce a distinct more severe phenotype. Our findings further support a recently proposed complex compound inheritance model in lethal lung developmental diseases and the contention that dual molecular diagnoses can parsimoniously explain blended phenotypes.
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http://dx.doi.org/10.1111/cge.13605DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6953252PMC
October 2019

Clinical, Histopathological, and Molecular Diagnostics in Lethal Lung Developmental Disorders.

Am J Respir Crit Care Med 2019 11;200(9):1093-1101

Department of Molecular and Human Genetics and.

Lethal lung developmental disorders are a rare but important group of pediatric diffuse lung diseases presenting with neonatal respiratory failure. On the basis of histopathological appearance at lung biopsy or autopsy, they have been termed: alveolar capillary dysplasia with misalignment of the pulmonary veins, acinar dysplasia, congenital alveolar dysplasia, and other unspecified primary pulmonary hypoplasias. However, the histopathological continuum in these lethal developmental disorders has made accurate diagnosis challenging, which has implications for recurrence risk. Over the past decade, genetic studies in infants with alveolar capillary dysplasia with misalignment of the pulmonary veins have revealed the causative role of the dosage-sensitive gene and its noncoding regulatory variants in the distant lung-specific enhancer at chromosome 16q24.1. In contrast, the molecular bases of acinar dysplasia and congenital alveolar dysplasia have remained poorly understood. Most recently, disruption of the TBX4-FGF10-FGFR2 epithelial-mesenchymal signaling pathway has been reported in patients with these lethal pulmonary dysplasias. Application of next-generation sequencing techniques, including exome sequencing and whole-genome sequencing, has demonstrated their complex compound inheritance. These data indicate that noncoding regulatory elements play a critical role in lung development in humans. We propose that for more precise lethal lung developmental disorder diagnosis, a diagnostic pathway including whole-genome sequencing should be implemented.
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http://dx.doi.org/10.1164/rccm.201903-0495TRDOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6888654PMC
November 2019

Multiple Differentially Methylated Regions Specific to Keratoconus Explain Known Keratoconus Linkage Loci.

Invest Ophthalmol Vis Sci 2019 04;60(5):1501-1509

Department of Genetics and Pharmaceutical Microbiology, Poznan University of Medical Sciences, Poznan, Poland.

Purpose: Keratoconus (KTCN) is a complex eye disorder resulting in loss of visual function. Its development is affected by genetic and environmental components. The aim of this study was to unravel the role of epigenetic factors in KTCN.

Methods: To verify if DNA methylation may play a role in KTCN development, reduced representation bisulfite sequencing of five KTCN and five non-KTCN human corneas was performed.

Results: Multiple KTCN-specific differentially methylated regions were detected and many of them overlap previously identified KTCN linkage loci (3p14.3, 5q35.2, 13q32.3, 15q24.1, and 20p13) and chromosome arms that have been linked to KTCN (2q, 4q, 5p, 9p, 14q, and 17q). Reanalysis of the previously described RNA sequencing dataset of 25 KTCN and 25 non-KTCN human corneas revealed that 12 genes downregulated in KTCN and 6 upregulated genes overlapped or were located in the near vicinity of the identified differentially methylated regions. Particularly interesting were the DNA methylation changes in WNT3 and WNT5A encoding Wnt ligands, as they provide a potential explanation for the Wnt signaling pathway dysregulation observed in KTCN.

Conclusions: We presented the results of data analysis from the first study of DNA methylation changes in human KTCN corneas compared to non-KTCN samples. We were able to identify genomic regions with distinct patterns of DNA hypo- and hypermethylation and link them to previously found KTCN susceptibility loci as well as transcriptomic disruption of Wnt signaling pathway observed in KTCN.
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http://dx.doi.org/10.1167/iovs.18-25916DOI Listing
April 2019

Novel parent-of-origin-specific differentially methylated loci on chromosome 16.

Clin Epigenetics 2019 04 8;11(1):60. Epub 2019 Apr 8.

Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, TX, USA.

Background: Congenital malformations associated with maternal uniparental disomy of chromosome 16, upd(16)mat, resemble those observed in newborns with the lethal developmental lung disease, alveolar capillary dysplasia with misalignment of pulmonary veins (ACDMPV). Interestingly, ACDMPV-causative deletions, involving FOXF1 or its lung-specific upstream enhancer at 16q24.1, arise almost exclusively on the maternally inherited chromosome 16. Given the phenotypic similarities between upd(16)mat and ACDMPV, together with parental allelic bias in ACDMPV, we hypothesized that there may be unknown imprinted loci mapping to chromosome 16 that become functionally unmasked by chromosomal structural variants.

Results: To identify parent-of-origin biased DNA methylation, we performed high-resolution bisulfite sequencing of chromosome 16 on peripheral blood and cultured skin fibroblasts from individuals with maternal or paternal upd(16) as well as lung tissue from patients with ACDMPV-causative 16q24.1 deletions and a normal control. We identified 22 differentially methylated regions (DMRs) with ≥ 5 consecutive CpG methylation sites and varying tissue-specificity, including the known DMRs associated with the established imprinted gene ZNF597 and DMRs supporting maternal methylation of PRR25, thought to be paternally expressed in lymphoblastoid cells. Lastly, we found evidence of paternal methylation on 16q24.1 near LINC01082 mapping to the FOXF1 enhancer.

Conclusions: Using high-resolution bisulfite sequencing to evaluate DNA methylation across chromosome 16, we found evidence for novel candidate imprinted loci on chromosome 16 that would not be evident in array-based assays and could contribute to the birth defects observed in patients with upd(16)mat or in ACDMPV.
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http://dx.doi.org/10.1186/s13148-019-0655-8DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6454695PMC
April 2019

Epigenetically dysregulated genes and pathways implicated in the pathogenesis of non-syndromic high myopia.

Sci Rep 2019 03 11;9(1):4145. Epub 2019 Mar 11.

Department of Obstetrics and Gynecology, Oakland University William Beaumont School of Medicine, Royal Oak, MI, USA.

Myopia, commonly referred to as nearsightedness, is one of the most common causes of visual disability throughout the world. It affects more people worldwide than any other chronic visual impairment condition. Although the prevalence varies among various ethnic groups, the incidence of myopia is increasing in all populations across globe. Thus, it is considered a pressing public health problem. Both genetics and environment play a role in development of myopia. To elucidate the epigenetic mechanism(s) underlying the pathophysiology of high-myopia, we conducted methylation profiling in 18 cases and 18 matched controls (aged 4-12 years), using Illumina MethylationEPIC BeadChips array. The degree of myopia was variable among subjects, ranging from -6 to -15D. We identified 1541 hypermethylated CpGs, representing 1745 genes (2.0-fold or higher) (false discovery rate (FDR) p ≤ 0.05), multiple CpGs were p < 5 × 10 with a receiver operating characteristic area under the curve (ROC-AUC) ≥ 0.75 in high-myopia subjects compared to controls. Among these, 48 CpGs had excellent correlation (AUC ≥ 0.90). Herein, we present the first genome-wide DNA methylation analysis in a unique high-myopia cohort, showing extensive and discrete methylation changes relative to controls. The genes we identified hold significant potential as targets for novel therapeutic intervention either alone, or in combination.
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http://dx.doi.org/10.1038/s41598-019-40299-xDOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6411983PMC
March 2019

Complex Compound Inheritance of Lethal Lung Developmental Disorders Due to Disruption of the TBX-FGF Pathway.

Am J Hum Genet 2019 02 10;104(2):213-228. Epub 2019 Jan 10.

Service de Génétique Médicale, CHU de Nantes, 44000 Nantes, France; Inserm, CNRS, Univ Nantes, l'institut du thorax, 44000 Nantes, France.

Primary defects in lung branching morphogenesis, resulting in neonatal lethal pulmonary hypoplasias, are incompletely understood. To elucidate the pathogenetics of human lung development, we studied a unique collection of samples obtained from deceased individuals with clinically and histopathologically diagnosed interstitial neonatal lung disorders: acinar dysplasia (n = 14), congenital alveolar dysplasia (n = 2), and other lethal lung hypoplasias (n = 10). We identified rare heterozygous copy-number variant deletions or single-nucleotide variants (SNVs) involving TBX4 (n = 8 and n = 2, respectively) or FGF10 (n = 2 and n = 2, respectively) in 16/26 (61%) individuals. In addition to TBX4, the overlapping ∼2 Mb recurrent and nonrecurrent deletions at 17q23.1q23.2 identified in seven individuals with lung hypoplasia also remove a lung-specific enhancer region. Individuals with coding variants involving either TBX4 or FGF10 also harbored at least one non-coding SNV in the predicted lung-specific enhancer region, which was absent in 13 control individuals with the overlapping deletions but without any structural lung anomalies. The occurrence of rare coding variants involving TBX4 or FGF10 with the putative hypomorphic non-coding SNVs implies a complex compound inheritance of these pulmonary hypoplasias. Moreover, they support the importance of TBX4-FGF10-FGFR2 epithelial-mesenchymal signaling in human lung organogenesis and help to explain the histopathological continuum observed in these rare lethal developmental disorders of the lung.
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http://dx.doi.org/10.1016/j.ajhg.2018.12.010DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6369446PMC
February 2019

LINE- and Alu-containing genomic instability hotspot at 16q24.1 associated with recurrent and nonrecurrent CNV deletions causative for ACDMPV.

Hum Mutat 2018 12 22;39(12):1916-1925. Epub 2018 Aug 22.

Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, Texas.

Transposable elements modify human genome by inserting into new loci or by mediating homology-, microhomology-, or homeology-driven DNA recombination or repair, resulting in genomic structural variation. Alveolar capillary dysplasia with misalignment of pulmonary veins (ACDMPV) is a rare lethal neonatal developmental lung disorder caused by point mutations or copy-number variant (CNV) deletions of FOXF1 or its distant tissue-specific enhancer. Eighty-five percent of 45 ACDMPV-causative CNV deletions, of which junctions have been sequenced, had at least one of their two breakpoints located in a retrotransposon, with more than half of them being Alu elements. We describe a novel ∼35 kb-large genomic instability hotspot at 16q24.1, involving two evolutionarily young LINE-1 (L1) elements, L1PA2 and L1PA3, flanking AluY, two AluSx, AluSx1, and AluJr elements. The occurrence of L1s at this location coincided with the branching out of the Homo-Pan-Gorilla clade, and was preceded by the insertion of AluSx, AluSx1, and AluJr. Our data show that, in addition to mediating recurrent CNVs, L1 and Alu retrotransposons can predispose the human genome to formation of variably sized CNVs, both of clinical and evolutionary relevance. Nonetheless, epigenetic or other genomic features of this locus might also contribute to its increased instability.
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http://dx.doi.org/10.1002/humu.23608DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6240370PMC
December 2018

CRISPR/Cas9-mediated deletion of lncRNA Gm26878 in the distant Foxf1 enhancer region.

Mamm Genome 2017 Aug 12;28(7-8):275-282. Epub 2017 Apr 12.

Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, TX, 77030, USA.

Recent genome editing techniques, including CRISPR mutagenesis screens, offer unparalleled opportunities to study the regulatory non-coding genomic regions, enhancers, promoters, and functional non-coding RNAs. Heterozygous point mutations in FOXF1 and genomic deletion copy-number variants at chromosomal region 16q24.1 involving FOXF1 or its regulatory region mapping ~300 kb upstream of FOXF1 and leaving it intact have been identified in the vast majority of patients with a lethal neonatal lung disease, alveolar capillary dysplasia with misalignment of pulmonary veins (ACDMPV). Homozygous Foxf1 mice have been shown to die by embryonic day 8.5 because of defects in the development of extraembryonic and lateral mesoderm-derived tissues, whereas heterozygous Foxf1 mice exhibit features resembling ACDMPV. We have previously defined a human lung-specific enhancer region encoding two long non-coding RNAs, LINC01081 and LINC01082, expressed in the lungs. To investigate the biological significance of lncRNAs in the Foxf1 enhancer region, we have generated a CRISPR/Cas9-mediated ~2.4 kb deletion involving the entire lncRNA-encoding gene Gm26878, located in the mouse region syntenic with the human Foxf1 upstream enhancer. Very recently, this mouse genomic region has been shown to function as a Foxf1 enhancer. Our results indicate that homozygous loss of Gm26878 is neonatal lethal with low penetrance. No changes in Foxf1 expression were observed, suggesting that the regulation of Foxf1 expression differs between mouse and human.
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http://dx.doi.org/10.1007/s00335-017-9686-7DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6502246PMC
August 2017

Collagen synthesis disruption and downregulation of core elements of TGF-β, Hippo, and Wnt pathways in keratoconus corneas.

Eur J Hum Genet 2017 05 1;25(5):582-590. Epub 2017 Feb 1.

Department of Genetics and Pharmaceutical Microbiology, Poznan University of Medical Sciences, Poznan, Poland.

To understand better the factors contributing to keratoconus (KTCN), we performed comprehensive transcriptome profiling of human KTCN corneas for the first time using an RNA-Seq approach. Twenty-five KTCN and 25 non-KTCN corneas were enrolled in this study. After RNA extraction, total RNA libraries were prepared and sequenced. The discovery RNA-Seq analysis (in eight KTCN and eight non-KTCN corneas) was conducted first, after which the replication RNA-Seq experiment was performed on a second set of samples (17 KTCN and 17 non-KTCN corneas). Over 82% of the genes and almost 75% of the transcripts detected as differentially expressed in KTCN and non-KTCN corneas were confirmed in the replication study using another set of samples. We used these differentially expressed genes to generate a network of KTCN-deregulated genes. We found an extensive disruption of collagen synthesis and maturation pathways, as well as downregulation of the core elements of the TGF-β, Hippo, and Wnt signaling pathways influencing corneal organization. This first comprehensive transcriptome profiling of human KTCN corneas points further to a complex etiology of KTCN.
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http://dx.doi.org/10.1038/ejhg.2017.4DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5437911PMC
May 2017

KTCNlncDB-a first platform to investigate lncRNAs expressed in human keratoconus and non-keratoconus corneas.

Database (Oxford) 2017 10;2017. Epub 2017 Jan 10.

Department of Genetics and Pharmaceutical Microbiology, Poznan University of Medical Sciences, Poznan, Poland.

Keratoconus (KTCN, OMIM 148300) is a degenerative eye disorder characterized by progressive stromal thinning that leads to a conical shape of the cornea, resulting in optical aberrations and even loss of visual function. The biochemical background of the disease is poorly understood, which motivated us to perform RNA-Seq experiment, aimed at better characterizing the KTCN transcriptome and identification of long non-coding RNAs (lncRNAs) that might be involved in KTCN etiology. The in silico functional studies based on predicted lncRNA:RNA base-pairings led us to recognition of a number of lncRNAs possibly regulating genes with known or plausible links to KTCN. The lncRNA sequences and data regarding their predicted functions in controlling the RNA processing and stability are available for browse, search and download in KTCNlncDB (http://rhesus.amu.edu.pl/KTCNlncDB/), the first online platform devoted to KTCN transcriptome.Database URL: http://rhesus.amu.edu.pl/KTCNlncDB/.
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http://dx.doi.org/10.1093/database/baw168DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5225396PMC
November 2017

Genomic strategies to understand causes of keratoconus.

Mol Genet Genomics 2017 Apr 28;292(2):251-269. Epub 2016 Dec 28.

Department of Genetics and Pharmaceutical Microbiology, Poznan University of Medical Sciences, Swiecickiego 4, Poznan, 60-781, Poland.

Keratoconus (KTCN) is a degenerative disorder of the eye characterized by the conical shape and thinning of the cornea. The abnormal structure of KTCN-affected cornea results in loss of visual acuity. While many studies examine how environmental factors influence disease development, finding the genetic triggers has been a major emphasis of KTCN research. This paper focuses on genomic strategies that were implemented for finding candidate genes, including linkage and association studies, and presents different approaches of mutation screening. The advantages and limitations of particular tools are discussed based on literature and personal experience. Since etiology underlying KTCN is complex, numerous findings indicating heterogeneity of genetic factors involved KTCN etiology are presented.
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http://dx.doi.org/10.1007/s00438-016-1283-zDOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5357269PMC
April 2017

Variants in SKP1, PROB1, and IL17B genes at keratoconus 5q31.1-q35.3 susceptibility locus identified by whole-exome sequencing.

Eur J Hum Genet 2017 01 5;25(1):73-78. Epub 2016 Oct 5.

Department of Genetics and Pharmaceutical Microbiology, Poznan University of Medical Sciences, Poznan, Poland.

Keratoconus (KTCN) is a protrusion and thinning of the cornea, resulting in impairment of visual function. The extreme genetic heterogeneity makes it difficult to discover factors unambiguously influencing the KTCN phenotype. In this study, we used whole-exome sequencing (WES) and Sanger sequencing to reduce the number of candidate genes at the 5q31.1-q35.3 locus and to prioritize other potentially relevant variants in an Ecuadorian family with KTCN. We applied WES in two affected KTCN individuals from the Ecuadorian family that showed a suggestive linkage between the KTCN phenotype and the 5q31.1-q35.3 locus. Putative variants identified by WES were further evaluated in this family using Sanger sequencing. Exome capture discovered a total of 173 rare (minor allele frequency <0.001 in control population) nonsynonymous variants in both affected individuals. Among them, 16 SNVs were selected for further evaluation. Segregation analysis revealed that variants c.475T>G in SKP1, c.671G>A in PROB1, and c.527G>A in IL17B in the 5q31.1-q35.3 linkage region, and c.850G>A in HKDC1 in the 10q22 locus completely segregated with the phenotype in the studied KTCN family. We demonstrate that a combination of various techniques significantly narrowed the studied genomic region and reduced the list of the putative exonic variants. Moreover, since this locus overlapped two other chromosomal regions previously recognized in distinct KTCN studies, our findings suggest that this 5q31.1-q35.3 locus might be linked with KTCN.
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http://dx.doi.org/10.1038/ejhg.2016.130DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5159765PMC
January 2017

Evidence against ZNF469 being causative for keratoconus in Polish patients.

Acta Ophthalmol 2016 May 25;94(3):289-94. Epub 2016 Jan 25.

Department of Genetics and Pharmaceutical Microbiology, Poznan University of Medical Sciences, Poznan, Poland.

Purpose: Keratoconus (KTCN) is a degenerative disorder characterized by stromal thinning and protrusion of the cornea, resulting in severe impairment of visual function. A recent study proposed that rare heterozygous mutations in ZNF469 determine KTCN aetiology.

Methods: To investigate the contribution of ZNF469 to KTCN, we Sanger sequenced ZNF469 in 42 unrelated Polish patients with KTCN and 49 Polish individuals with high myopia (HM) and compared the results with whole-exome sequencing (WES) data performed in 268 Polish individuals without ocular abnormalities.

Results: The average number of ZNF469 non-synonymous variants was 16.31 and 16.0 for individuals with KTCN and HM, respectively (p = 0.3724). All identified variants were previously reported. Alternative allele frequency (AAF) was determined based on the WES results. Among missense variants, only one (rs528085780) has AAF ≤ 0.001 and was identified in one patient with sporadic KTCN. However, the resulting Arg1864Lys substitution was not predicted to be deleterious.

Conclusion: In summary, we have not found a significant enrichment of sequence variants in ZNF469 in Polish patients with KTCN. High prevalence of ZNF469 variants identified in our KTCN group is typical for a common genetic variation observed in general population. Our findings indicate that variation in ZNF469 is not responsible for KTCN and other genetic variants are involved in the development and progression of this disease in Polish patients.
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http://dx.doi.org/10.1111/aos.12968DOI Listing
May 2016

Variant c.2262A>C in DOCK9 Leads to Exon Skipping in Keratoconus Family.

Invest Ophthalmol Vis Sci 2015 Dec;56(13):7687-90

Department of Genetics and Pharmaceutical Microbiology, Poznan University of Medical Sciences, Poznan, Poland 2Institute of Human Genetics, Polish Academy of Sciences, Poznan, Poland.

Purpose: Keratoconus (KTCN) is a degenerative disorder of the eye that is characterized by a conical shape and thinning of the cornea, resulting in impaired visual function. Previously, we identified heterozygous single base-pair substitutions in DOCK9, IPO5, and STK24, showing concurrent 100% segregation with the affected phenotype in an Ecuadorian family. As the pathogenic consequences of these variants were not obvious, we performed in vitro splicing analyses to determine their functional significance.

Methods: We generated expression constructs using patient DNA as a template corresponding to the wild-type and mutant alleles of DOCK9, IPO5, and STK24. After transfecting HeLa cells with each construct, total RNA samples were extracted, reverse transcribed, and amplified using specific primers.

Results: In vitro splicing analysis revealed that only c.2262A>C in exon 20 of DOCK9 led to aberrant splicing, resulting in the changed ratio between two protein isoforms: a normal transcript and a transcript with exon skipping. The exon skipping causes a premature stop codon, disrupting the functional domains of DOCK9 protein, which may alter the biological role of DOCK9 as a Cdc42 activator.

Conclusions: Based on in vitro results, we demonstrated that c.2262A>C substitution in DOCK9, previously identified in KTCN-affected members of an Ecuadorian family, leads to a splicing aberration. However, because the mutation effect was observed in vitro, a definitive relationship between DOCK9 and KTCN phenotype could not be established. Our results indicate that further elucidation of the causes of KTCN is needed.
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http://dx.doi.org/10.1167/iovs.15-17538DOI Listing
December 2015
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