Publications by authors named "Dorothy K Grange"

108 Publications

Behavioral and cognitive functioning in individuals with Cantú syndrome.

Am J Med Genet A 2021 Aug 30;185(8):2434-2444. Epub 2021 May 30.

Department of Clinical Genetics, Amsterdam University Medical Centers, Amsterdam, The Netherlands.

Cantú syndrome (CS) is caused by pathogenic variants in ABCC9 and KCNJ8 encoding the regulatory and pore-forming subunits of ATP-sensitive potassium (K ) channels. CS is characterized by congenital hypertrichosis, distinctive facial features, peripheral edema, and cardiac and neurodevelopmental abnormalities. Behavioral and cognitive issues have been self-reported by some CS individuals, but results of formal standardized investigations have not been published. To assess the cognitive profile, social functioning, and psychiatric symptoms in a large group of CS subjects systematically in a cross-sectional manner, we invited 35 individuals (1-69 years) with confirmed ABCC9 variants and their relatives to complete various commonly applied standardized age-related questionnaires, including the Kaufman brief intelligence test 2, the social responsiveness scale-2, and the Achenbach system of empirically based assessment. The majority of CS individuals demonstrated average verbal and nonverbal intelligence compared to the general population. Fifteen percent of cases showed social functioning strongly associated with a clinical diagnosis of autism spectrum disorder. Both externalizing and internalizing problems were also present in this cohort. In particular, anxiety, anxiety or attention deficit hyperactivity disorder, and autism spectrum behaviors were predominantly observed in the younger subjects in the cohort (≥25%), but this percentage decreased markedly in adults.
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http://dx.doi.org/10.1002/ajmg.a.62348DOI Listing
August 2021

Variants in PRKAR1B cause a neurodevelopmental disorder with autism spectrum disorder, apraxia, and insensitivity to pain.

Genet Med 2021 Apr 8. Epub 2021 Apr 8.

Institute of Human Genetics, Heidelberg University, Heidelberg, Germany.

Purpose: We characterize the clinical and molecular phenotypes of six unrelated individuals with intellectual disability and autism spectrum disorder who carry heterozygous missense variants of the PRKAR1B gene, which encodes the R1β subunit of the cyclic AMP-dependent protein kinase A (PKA).

Methods: Variants of PRKAR1B were identified by single- or trio-exome analysis. We contacted the families and physicians of the six individuals to collect phenotypic information, performed in vitro analyses of the identified PRKAR1B-variants, and investigated PRKAR1B expression during embryonic development.

Results: Recent studies of large patient cohorts with neurodevelopmental disorders found significant enrichment of de novo missense variants in PRKAR1B. In our cohort, de novo origin of the PRKAR1B variants could be confirmed in five of six individuals, and four carried the same heterozygous de novo variant c.1003C>T (p.Arg335Trp; NM_001164760). Global developmental delay, autism spectrum disorder, and apraxia/dyspraxia have been reported in all six, and reduced pain sensitivity was found in three individuals carrying the c.1003C>T variant. PRKAR1B expression in the brain was demonstrated during human embryonal development. Additionally, in vitro analyses revealed altered basal PKA activity in cells transfected with variant-harboring PRKAR1B expression constructs.

Conclusion: Our study provides strong evidence for a PRKAR1B-related neurodevelopmental disorder.
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http://dx.doi.org/10.1038/s41436-021-01152-7DOI Listing
April 2021

Fatal COVID-19 infection in a patient with long-chain 3-hydroxyacyl-CoA dehydrogenase deficiency: A case report.

JIMD Rep 2020 Nov 10;56(1):40-45. Epub 2020 Sep 10.

Division of Genetics and Genomic Medicine, Department of Pediatrics Washington University School of Medicine St Louis Missouri USA.

Long-chain fatty-acyl CoA dehydrogenase deficiency (LCHADD) is an inborn error of long chain fatty acid oxidation with various features including hypoketotic hypoglycemia, recurrent rhabdomyolysis, pigmentary retinopathy, peripheral neuropathy, cardiomyopathy, and arrhythmias. Various stresses trigger metabolic decompensation. Coronavirus disease 2019 (COVID-19) is a pandemic caused by the RNA virus SARS-CoV-2 with diverse presentations ranging from respiratory symptoms to myocarditis. We report a case of a patient with LCHADD who initially presented with typical metabolic decompensation symptoms including nausea, vomiting, and rhabdomyolysis in addition to mild cough, and was found to have COVID-19. She developed acute respiratory failure and refractory hypotension from severe cardiomyopathy which progressed to multiple organ failure and death. Our case illustrates the need for close monitoring of cardiac function in patients with a long-chain fatty acid oxidation disorder.
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http://dx.doi.org/10.1002/jmd2.12165DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7653242PMC
November 2020

Kir6.1- and SUR2-dependent KATP over-activity disrupts intestinal motility in murine models of Cantu Syndrome.

JCI Insight 2020 Nov 10. Epub 2020 Nov 10.

Department of Cell Biology and Physiology, Washington University School of Medicine, St. Louis, United States of America.

Cantύ Syndrome (CS), caused by gain-of-function (GOF) mutations in pore-forming (Kir6.1, KCNJ8) and accessory (SUR2, ABCC9) ATP-sensitive potassium (KATP) channel subunit genes, is frequently accompanied by gastrointestinal (GI) dysmotility, and we describe one CS patient who required an implanted intestinal irrigation system for successful stooling. We used gene-modified mice to assess the underlying KATP channel subunits in gut smooth muscle, and to model the consequences of altered KATP channels in CS gut. We show that Kir6.1/SUR2 subunits underlie smooth muscle KATP channels throughout the small intestine and colon. Knock-in mice, carrying human KCNJ8 and ABCC9 CS mutations in the endogenous loci, exhibit reduced intrinsic contractility throughout the intestine, resulting in death when weaned onto solid food in the most severely affected animals. Death is avoided by weaning onto a liquid gel diet, implicating intestinal insufficiency and bowel impaction as the underlying cause, and GI transit is normalized by treatment with the KATP inhibitor glibenclamide. We thus define the molecular basis of intestinal KATP channel activity, the mechanism by which overactivity results in GI insufficiency, and a viable approach to therapy.
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http://dx.doi.org/10.1172/jci.insight.141443DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7714409PMC
November 2020

Newborn Screening for Pompe Disease in Illinois: Experience with 684,290 Infants.

Int J Neonatal Screen 2020 03 21;6(1). Epub 2020 Jan 21.

Newborn Screening Laboratory, Illinois Department of Public Health, Chicago, IL 60603, USA; (R.S.); (K.B.).

Statewide newborn screening for Pompe disease began in Illinois in 2015. As of 30 September 2019, a total of 684,290 infants had been screened and 395 infants (0.06%) were screen positive. A total of 29 cases of Pompe disease were identified (3 infantile, 26 late-onset). While many of the remainder were found to have normal alpha-glucosidase activity on the follow-up testing (234 of 395), other findings included 62 carriers, 39 infants with pseudodeficiency, and eight infants who could not be given a definitive diagnosis due to inconclusive follow-up testing.
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http://dx.doi.org/10.3390/ijns6010004DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7422983PMC
March 2020

Enhanced MAPK1 Function Causes a Neurodevelopmental Disorder within the RASopathy Clinical Spectrum.

Am J Hum Genet 2020 09 27;107(3):499-513. Epub 2020 Jul 27.

Institute of Human Genetics, University Hospital Magdeburg, 39120 Magdeburg, Germany.

Signal transduction through the RAF-MEK-ERK pathway, the first described mitogen-associated protein kinase (MAPK) cascade, mediates multiple cellular processes and participates in early and late developmental programs. Aberrant signaling through this cascade contributes to oncogenesis and underlies the RASopathies, a family of cancer-prone disorders. Here, we report that de novo missense variants in MAPK1, encoding the mitogen-activated protein kinase 1 (i.e., extracellular signal-regulated protein kinase 2, ERK2), cause a neurodevelopmental disease within the RASopathy phenotypic spectrum, reminiscent of Noonan syndrome in some subjects. Pathogenic variants promote increased phosphorylation of the kinase, which enhances translocation to the nucleus and boosts MAPK signaling in vitro and in vivo. Two variant classes are identified, one of which directly disrupts binding to MKP3, a dual-specificity protein phosphatase negatively regulating ERK function. Importantly, signal dysregulation driven by pathogenic MAPK1 variants is stimulus reliant and retains dependence on MEK activity. Our data support a model in which the identified pathogenic variants operate with counteracting effects on MAPK1 function by differentially impacting the ability of the kinase to interact with regulators and substrates, which likely explains the minor role of these variants as driver events contributing to oncogenesis. After nearly 20 years from the discovery of the first gene implicated in Noonan syndrome, PTPN11, the last tier of the MAPK cascade joins the group of genes mutated in RASopathies.
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http://dx.doi.org/10.1016/j.ajhg.2020.06.018DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7477014PMC
September 2020

Siblings with a novel MED12 variant and Odho syndrome with immune defects.

Clin Genet 2020 09 26;98(3):308-310. Epub 2020 Jul 26.

Department of Pediatrics, Division of Rheumatology/Immunology, Washington University School of Medicine, St. Louis, Missouri, USA.

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http://dx.doi.org/10.1111/cge.13806DOI Listing
September 2020

Pegvaliase for the treatment of phenylketonuria: Results of the phase 2 dose-finding studies with long-term follow-up.

Mol Genet Metab 2020 08 16;130(4):239-246. Epub 2020 Jun 16.

Department of Pediatrics, Section of Clinical Genetics and Metabolism, University of Colorado School of Medicine, 12605 E 16th St, Aurora, CO 80045, United States of America. Electronic address:

Background: Phenylketonuria (PKU) is characterized by a deficiency in phenylalanine hydroxylase (PAH) that may lead to elevated blood phenylalanine (Phe) and significant neurocognitive and neuropsychological comorbidities. Pegvaliase (PALYNZIQ®, BioMarin Pharmaceutical Inc.) is a PEGylated recombinant Anabaena variabilis phenylalanine ammonia lyase (PAL), which converts Phe to trans-cinnamic acid and ammonia, and was approved in May 2018 in the United States and in May 2019 in the European Union for decreasing blood Phe levels in adults with PKU with blood Phe levels >600 μmol/L. The efficacy and safety of pegvaliase was assessed in two phase 2 dose-finding studies in adults with PKU (PAL-002, NCT00925054, and PAL-004, NCT01212744). Participants completing these studies could enroll in a long-term extension study (PAL-003, NCT00924703).

Methods: Participants in PAL-002 received pegvaliase 0.001, 0.003, 0.01, 0.03, or 0.1 mg/kg weekly for 8 weeks, then continued treatment for a further 8 weeks with dose and/or frequency adjusted to achieve blood Phe concentrations of 60 to 600 μmol/L. Participants in PAL-004 received pegvaliase 0.001 to 0.4 mg/kg 5 days/week for 13 weeks, with modifications made to the starting dose in response to safety and/or efficacy, followed by 3 additional weeks of follow-up assessments. The maximum allowable daily dose in both studies was 1.0 mg/kg/day (5.0 mg/kg/week). Participants who completed any of the phase 2 studies (PAL-002; PAL-004; or a third phase 2 study, 165-205) were eligible to enroll in an open-label, multicenter, long-term extension study (PAL-003, NCT00924703).

Results: Thirty-seven of the 40 enrolled participants completed PAL-002 and 15 of the 16 enrolled participants completed PAL-004. Mean blood Phe at baseline was 1311.0 (standard deviation [SD] 354) μmol/L in PAL-002 and 1482.1 (SD 363.5) μmol/L in PAL-004. Mean blood Phe did not substantially decrease with pegvaliase treatment in PAL-002 (-206.3 [SD 287.1] μmol/L at Week 16) or PAL-004 (-410.8 [SD 653.7] μmol/L at Week 13). In PAL-004, mean blood Phe dropped from baseline by 929.1 μmol/L (SD 691.1) by Week 2; subsequent to dose modifications and interruptions, this early decrease in mean Phe level was not sustained. With increased pegvaliase dose and duration in PAL-003, mean blood Phe levels steadily decreased from baseline, with mean reductions by Week 120 of 68.8% (SD 44.2%) in PAL-002 participants and 75.9% (SD 32.4%) in PAL-004 participants. All participants in PAL-002 and PAL-004 reported ≥1 adverse event (AE), with higher exposure-adjusted event rates in PAL-004. The majority of AEs were mild (87.2% in PAL-002, 86.7% in PAL-004) or moderate (12.4% in PAL-002, 13.3% in PAL-004). The most commonly reported AEs in PAL-002 were injection site reaction (50.0% of participants), headache (42.1%), injection site erythema (36.8%), nausea (34.2%), and arthralgia (29.0%), and in PAL-004 were arthralgia (75.0%), headache (62.5%), dizziness (56.3%), injection site erythema (56.3%), and injection site reaction (50.0%).

Conclusions: In two phase 2 dose-finding studies, pegvaliase did not lead to substantial blood Phe reductions. Higher and more frequent pegvaliase dosing in PAL-004 led to a substantial initial drop in blood Phe, but an increase in the number of hypersensitivity AEs and dose reductions or interruptions. With increased dose and duration of treatment in PAL-003, mean blood Phe reduction was substantial and sustained, and the frequency of hypersensitivity AEs decreased and stabilized. Together, these studies led to the development of an induction-titration-maintenance regimen that has been approved for pegvaliase, with patients starting at a low weekly dose that gradually increases in dose and frequency until they achieve a standard non-weight-based daily maintenance dose. This regimen has been tested in a third phase 2 study, as well as in two successful phase 3 studies of pegvaliase.
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http://dx.doi.org/10.1016/j.ymgme.2020.06.006DOI Listing
August 2020

Safety and immunogenicity of Fc-EDA, a recombinant ectodysplasin A1 replacement protein, in human subjects.

Br J Clin Pharmacol 2020 10 24;86(10):2063-2069. Epub 2020 Apr 24.

Center for Ectodermal Dysplasias, University Hospital Erlangen, Germany.

In X-linked hypohidrotic ectodermal dysplasia, the most frequent ectodermal dysplasia, an inherited deficiency of the signalling protein ectodysplasin A1 (EDA1) impairs the development of the skin and its appendages, various eccrine glands, and dentition. The severe hypohidrosis common to X-linked hypohidrotic ectodermal dysplasia patients may lead to life-threatening hyperthermia, especially during hot weather or febrile illness. Fc-EDA, an EDA1 replacement protein known to prevent the disease in newborn animals, was tested in 2 clinical trials (human adults and neonates) and additionally administered under compassionate use to 3 infants in utero. The data support the safety of Fc-EDA and efficacy if applied prenatally. Anti-drug antibodies were detected after intravenous administration in adult males and nonpregnant females, but not in pregnant women when Fc-EDA was delivered intra-amniotically. Most importantly, there was no detectable immune response to the investigational drug in neonates treated by intravenous infusions and in infants who had received Fc-EDA in utero. In conclusion, the safety profile of this drug encourages further development of prenatal EDA1 replacement therapy.
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http://dx.doi.org/10.1111/bcp.14301DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7495278PMC
October 2020

Three-dimensional facial morphology in Cantú syndrome.

Am J Med Genet A 2020 05 26;182(5):1041-1052. Epub 2020 Feb 26.

Department of Clinical Genetics, Amsterdam Medical Center, University of Amsterdam, Amsterdam, The Netherlands.

Cantú syndrome (CS) was first described in 1982, and is caused by pathogenic variants in ABCC9 and KCNJ8 encoding regulatory and pore forming subunits of ATP-sensitive potassium (K ) channels, respectively. It is characterized by congenital hypertrichosis, osteochondrodysplasia, extensive cardiovascular abnormalities and distinctive facial anomalies including a broad nasal bridge, long philtrum, epicanthal folds, and prominent lips. Many genetic syndromes, such as CS, involve facial anomalies that serve as a significant clue in the initial identification of the respective disorder before clinical or molecular diagnosis are undertaken. However, an overwhelming number of CS patients receive misdiagnoses based on an evaluation of coarse facial features. By analyzing three-dimensional images of CS faces, we quantified facial dysmorphology in a cohort of both male and female CS patients with confirmed ABCC9 variants. Morphometric analysis of different regions of the face revealed gender-specific significant differences in face shape. Moreover, we show that 3D facial photographs can distinguish between CS and other genetic disorders with specific facial dysmorphologies that have been mistaken for CS-associated anomalies in the past, hence assisting in an earlier clinical and molecular diagnosis. This optimizes genetic counseling and reduces stress for patients and parents by avoiding unnecessary misdiagnosis.
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http://dx.doi.org/10.1002/ajmg.a.61517DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7217184PMC
May 2020

Phenotypic expansion of KMT2D-related disorder: Beyond Kabuki syndrome.

Am J Med Genet A 2020 05 21;182(5):1053-1065. Epub 2020 Feb 21.

Department of Pediatrics, Washington University School of Medicine, St. Louis, Missouri, USA.

Pathogenic variants in KMT2D, which encodes lysine specific methyltransferase 2D, cause autosomal dominant Kabuki syndrome, associated with distinctive dysmorphic features including arched eyebrows, long palpebral fissures with eversion of the lower lid, large protuberant ears, and fetal finger pads. Most disease-causing variants identified to date are putative loss-of-function alleles, although 15-20% of cases are attributed to missense variants. We describe here four patients (including one previously published patient) with de novo KMT2D missense variants and with shared but unusual clinical findings not typically seen in Kabuki syndrome, including athelia (absent nipples), choanal atresia, hypoparathyroidism, delayed or absent pubertal development, and extreme short stature. These individuals also lack the typical dysmorphic facial features found in Kabuki syndrome. Two of the four patients had severe interstitial lung disease. All of these variants cluster within a 40-amino-acid region of the protein that is located just N-terminal of an annotated coiled coil domain. These findings significantly expand the phenotypic spectrum of features associated with variants in KMT2D beyond those seen in Kabuki syndrome and suggest a possible new underlying disease mechanism for these patients.
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http://dx.doi.org/10.1002/ajmg.a.61518DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7295006PMC
May 2020

De novo TBR1 variants cause a neurocognitive phenotype with ID and autistic traits: report of 25 new individuals and review of the literature.

Eur J Hum Genet 2020 06 31;28(6):770-782. Epub 2020 Jan 31.

Department of Pediatrics, The Barbara Bush Children's Hospital, Maine Medical Center, Portland, OR, USA.

TBR1, a T-box transcription factor expressed in the cerebral cortex, regulates the expression of several candidate genes for autism spectrum disorders (ASD). Although TBR1 has been reported as a high-confidence risk gene for ASD and intellectual disability (ID) in functional and clinical reports since 2011, TBR1 has only recently been recorded as a human disease gene in the OMIM database. Currently, the neurodevelopmental disorders and structural brain anomalies associated with TBR1 variants are not well characterized. Through international data sharing, we collected data from 25 unreported individuals and compared them with data from the literature. We evaluated structural brain anomalies in seven individuals by analysis of MRI images, and compared these with anomalies observed in TBR1 mutant mice. The phenotype included ID in all individuals, associated to autistic traits in 76% of them. No recognizable facial phenotype could be identified. MRI analysis revealed a reduction of the anterior commissure and suggested new features including dysplastic hippocampus and subtle neocortical dysgenesis. This report supports the role of TBR1 in ID associated with autistic traits and suggests new structural brain malformations in humans. We hope this work will help geneticists to interpret TBR1 variants and diagnose ASD probands.
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http://dx.doi.org/10.1038/s41431-020-0571-6DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7253452PMC
June 2020

Loss-of-Function Variants in PPP1R12A: From Isolated Sex Reversal to Holoprosencephaly Spectrum and Urogenital Malformations.

Am J Hum Genet 2020 01 26;106(1):121-128. Epub 2019 Dec 26.

The Prenatal Diagnosis and Medical Genetics Program, Department of Obstetrics and Gynecology, Mount Sinai Hospital, University of Toronto, Toronto, Ontario, M5G 1X5, Canada; Division of Clinical and Metabolic Genetics, Department of Pediatrics, The Hospital for Sick Children, University of Toronto, Toronto, Ontario, M5G 1X8, Canada.

In two independent ongoing next-generation sequencing projects for individuals with holoprosencephaly and individuals with disorders of sex development, and through international research collaboration, we identified twelve individuals with de novo loss-of-function (LoF) variants in protein phosphatase 1, regulatory subunit 12a (PPP1R12A), an important developmental gene involved in cell migration, adhesion, and morphogenesis. This gene has not been previously reported in association with human disease, and it has intolerance to LoF as illustrated by a very low observed-to-expected ratio of LoF variants in gnomAD. Of the twelve individuals, midline brain malformations were found in five, urogenital anomalies in nine, and a combination of both phenotypes in two. Other congenital anomalies identified included omphalocele, jejunal, and ileal atresia with aberrant mesenteric blood supply, and syndactyly. Six individuals had stop gain variants, five had a deletion or duplication resulting in a frameshift, and one had a canonical splice acceptor site loss. Murine and human in situ hybridization and immunostaining revealed PPP1R12A expression in the prosencephalic neural folds and protein localization in the lower urinary tract at critical periods for forebrain division and urogenital development. Based on these clinical and molecular findings, we propose the association of PPP1R12A pathogenic variants with a congenital malformations syndrome affecting the embryogenesis of the brain and genitourinary systems and including disorders of sex development.
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http://dx.doi.org/10.1016/j.ajhg.2019.12.004DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7042489PMC
January 2020

Cantú syndrome: Findings from 74 patients in the International Cantú Syndrome Registry.

Am J Med Genet C Semin Med Genet 2019 12;181(4):658-681

Department of Genetics, Center for Molecular Medicine, University Medical Center Utrecht, Utrecht University, Utrecht, The Netherlands.

Cantú syndrome (CS), first described in 1982, is caused by pathogenic variants in ABCC9 and KCNJ8, which encode the regulatory and pore forming subunits of ATP-sensitive potassium (K ) channels, respectively. Multiple case reports of affected individuals have described the various clinical features of CS, but systematic studies are lacking. To define the effects of genetic variants on CS phenotypes and clinical outcomes, we have developed a standardized REDCap-based registry for CS. We report phenotypic features and associated genotypes on 74 CS subjects, with confirmed ABCC9 variants in 72 of the individuals. Hypertrichosis and a characteristic facial appearance are present in all individuals. Polyhydramnios during fetal life, hyperflexibility, edema, patent ductus arteriosus (PDA), cardiomegaly, dilated aortic root, vascular tortuosity of cerebral arteries, and migraine headaches are common features, although even with this large group of subjects, there is incomplete penetrance of CS-associated features, without clear correlation to genotype.
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http://dx.doi.org/10.1002/ajmg.c.31753DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7654223PMC
December 2019

Clinical and Pathological Features of a Newborn With Compound Heterozygous Variants.

Pediatr Dev Pathol 2020 May-Jun;23(3):235-239. Epub 2019 Oct 21.

Department of Pathology and Immunology, Washington University School of Medicine, St. Louis, Missouri.

We report a term female infant born to nonconsanguineous parents who presented with renal failure at birth, hypothyroidism, cholestasis, and progressive cardiac dysfunction. Multigene next-generation sequencing panels for cholestasis, cardiomyopathy, and cystic renal disease did not reveal a unifying diagnosis. Whole exome sequencing revealed compound heterozygous pathogenic variants in (Ankyrin Repeat and Sterile Alpha Motif Domain Containing 6), which encodes a protein that interacts with other proteins of the Inv compartment of cilium (, , and ). has been shown to be important for early renal development and cardiac looping in animal models. Autopsy revealed cystic renal dysplasia and cardiomyocyte hypertrophy, disarray, and focal necrosis. Liver histology revealed cholestasis and centrilobular necrosis, which was likely a result of progressive cardiac failure. This is the first report of compound heterozygous variants in leading to a nephronopthisis-related ciliopathy-like phenotype. We conclude that pathogenic variants in may present early in life with severe renal and cardiac failure, similar to subjects with variants in genes encoding other proteins in the Inv compartment of the cilium.
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http://dx.doi.org/10.1177/1093526619881541DOI Listing
March 2021

White and gray matter brain development in children and young adults with phenylketonuria.

Neuroimage Clin 2019 2;23:101916. Epub 2019 Jul 2.

Department of Psychological & Brain Sciences, Campus Box 1125, Washington University, St. Louis, MO, United States; Department of Pediatrics, Washington University School of Medicine, St. Louis, MO, United States.

Phenylketonuria (PKU) is a recessive disorder characterized by disruption in the metabolism of the amino acid phenylalanine (Phe). Prior research indicates that individuals with PKU have substantial white matter (WM) compromise. Much less is known about gray matter (GM) in PKU, but a small body of research suggests volumetric differences compared to controls. To date, developmental trajectories of GM structure in individuals with PKU have not been examined, nor have trajectories of WM and GM been examined within a single study. To address this gap in the literature, we compared longitudinal brain development over a three-year period in individuals with PKU (n = 35; 18 male) and typically-developing controls (n = 71; 35 male) aged 7-21 years. Using diffusion tensor imaging (DTI) and structural magnetic resonance imaging (MRI), we observed whole-brain and regional WM differences between individuals with PKU and controls, which were often exacerbated with increasing age. In marked contrast with trajectories of WM development, trajectories of GM development did not differ between individuals with PKU and controls, indicating that neuropathology in PKU is more prominent in WM than GM. Within individuals with PKU, mediation analyses revealed that whole-brain mean diffusivity (MD) and regional MD in the corpus callosum and centrum semiovale mediated the relationship between dietary treatment compliance (i.e., Phe control) and executive abilities, suggesting a plausible neurobiological mechanism by which Phe control may influence cognitive outcomes. Our findings clarify the specificity, timing, and cognitive consequences of whole-brain and regional WM pathology, with implications for treatment and research in PKU.
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http://dx.doi.org/10.1016/j.nicl.2019.101916DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6627563PMC
August 2020

Population-Based Newborn Screening for Mucopolysaccharidosis Type II in Illinois: The First Year Experience.

J Pediatr 2019 11 30;214:165-167.e1. Epub 2019 Aug 30.

Newborn Screening Laboratory, Illinois Department of Public Health, Chicago, IL.

Objectives: To assess the outcome of population-based newborn screening for mucopolysaccharidosis type II (MPS II) during the first year of screening in Illinois.

Study Design: Tandem mass spectrometry was used to measure iduronate-2-sulfatase (I2S) activity in dried blood spot specimens obtained from 162 000 infant samples sent to the Newborn Screening Laboratory of the Illinois Department of Public Health in Chicago.

Results: One case of MPS II and 14 infants with pseudodeficiency for I2S were identified.

Conclusions: Newborn screening for MPS II by measurement of I2S enzyme activity was successfully integrated into the statewide newborn screening program in Illinois.
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http://dx.doi.org/10.1016/j.jpeds.2019.07.053DOI Listing
November 2019

Glibenclamide treatment in a Cantú syndrome patient with a pathogenic ABCC9 gain-of-function variant: Initial experience.

Am J Med Genet A 2019 08 7;179(8):1585-1590. Epub 2019 Jun 7.

Center for the Investigation of Membrane Excitability Diseases, Washington University School of Medicine, St. Louis, Missouri.

Cantú syndrome (CS), characterized by hypertrichosis, distinctive facial features, and complex cardiovascular abnormalities, is caused by pathogenic variants in ABCC9 and KCNJ8 genes. These genes encode gain-of-function mutations in the regulatory (SUR2) and pore-forming (Kir6.1) subunits of K channels, respectively, suggesting that channel-blocking sulfonylureas could be a viable therapy. Here we report a neonate with CS, carrying a heterozygous ABCC9 variant (c.3347G>A, p.Arg1116His), born prematurely at 32 weeks gestation. Initial echocardiogram revealed a large patent ductus arteriosus (PDA), and high pulmonary pressures with enlarged right ventricle. He initially received surfactant and continuous positive airway pressure ventilation and was invasively ventilated for 4 weeks, until PDA ligation. After surgery, he still had ongoing bilevel positive airway pressure (BiPAP) requirement, but was subsequently weaned to nocturnal BiPAP. He was treated for pulmonary hypertension with Sildenafil, but failed to make further clinical improvement. A therapeutic glibenclamide trial was commenced in week 11 (initial dose of 0.05 mg kg day in two divided doses). After 1 week of treatment, he began to tolerate time off BiPAP when awake, and edema improved. Glibenclamide was well tolerated, and the dose was slowly increased to 0.15 mg kg day over the next 12 weeks. Mild transient hypoglycemia was observed, but there was no cardiovascular dysfunction. Confirmation of therapeutic benefit will require studies of more CS patients but, based on this limited experience, consideration should be given to glibenclamide as CS therapy, although problems associated with prematurity, and complications of hypoglycemia, might limit outcome in critically ill neonates with CS.
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http://dx.doi.org/10.1002/ajmg.a.61200DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6899598PMC
August 2019

Biallelic variants in SMAD6 are associated with a complex cardiovascular phenotype.

Hum Genet 2019 Jun 8;138(6):625-634. Epub 2019 Apr 8.

Institute of Human Genetics, University Medical Center Hamburg-Eppendorf, Martinistraße 52, 20246, Hamburg, Germany.

Rare heterozygous variants in SMAD6 have been identified as a significant genetic contributor to bicuspid aortic valve-associated thoracic aortic aneurysm on one hand and non-syndromic midline craniosynostosis on the other. In this study, we report two individuals with biallelic missense variants in SMAD6 and a complex cardiac phenotype. Trio exome sequencing in Proband 1, a male who had aortic isthmus stenosis, revealed the homozygous SMAD6 variant p.(Ile466Thr). He also had mild intellectual disability and radio-ulnar synostosis. Proband 2 is a female who presented with a more severe cardiac phenotype with a dysplastic and stenotic pulmonary valve and dilated cardiomyopathy. In addition, she had vascular anomalies, including a stenotic left main coronary artery requiring a bypass procedure, narrowing of the proximal left pulmonary artery and a venous anomaly in the brain. Proband 2 has compound heterozygous SMAD6 missense variants, p.(Phe357Ile) and p.(Ser483Pro). Absence of these SMAD6 variants in the general population and high pathogenicity prediction scores suggest that these variants caused the probands' phenotypes. This is further corroborated by cardiovascular anomalies and appendicular skeletal defects in Smad6-deficient mice. SMAD6 acts as an inhibitory SMAD and preferentially inhibits bone morphogenetic protein (BMP)-induced signaling. Our data suggest that biallelic variants in SMAD6 may affect the inhibitory activity of SMAD6 and cause enhanced BMP signaling underlying the cardiovascular anomalies and possibly other clinical features in the two probands.
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http://dx.doi.org/10.1007/s00439-019-02011-xDOI Listing
June 2019

Dichotomous roles of in the establishment of atrioventricular conduction pathways in the human heart.

HeartRhythm Case Rep 2019 Feb 20;5(2):109-111. Epub 2018 Nov 20.

Department of Pediatrics, Washington University School of Medicine, St. Louis, Missouri.

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http://dx.doi.org/10.1016/j.hrcr.2018.11.005DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6379565PMC
February 2019

Variants in TCF20 in neurodevelopmental disability: description of 27 new patients and review of literature.

Genet Med 2019 09 11;21(9):2036-2042. Epub 2019 Feb 11.

Spectrum Health Medical Genetics, Grand Rapids, MI, USA.

Purpose: To define the clinical characteristics of patients with variants in TCF20, we describe 27 patients, 26 of whom were identified via exome sequencing. We compare detailed clinical data with 17 previously reported patients.

Methods: Patients were ascertained through molecular testing laboratories performing exome sequencing (and other testing) with orthogonal confirmation; collaborating referring clinicians provided detailed clinical information.

Results: The cohort of 27 patients all had novel variants, and ranged in age from 2 to 68 years. All had developmental delay/intellectual disability. Autism spectrum disorders/autistic features were reported in 69%, attention disorders or hyperactivity in 67%, craniofacial features (no recognizable facial gestalt) in 67%, structural brain anomalies in 24%, and seizures in 12%. Additional features affecting various organ systems were described in 93%. In a majority of patients, we did not observe previously reported findings of postnatal overgrowth or craniosynostosis, in comparison with earlier reports.

Conclusion: We provide valuable data regarding the prognosis and clinical manifestations of patients with variants in TCF20.
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http://dx.doi.org/10.1038/s41436-019-0454-9DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7171701PMC
September 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

Bi-allelic POLR3A Loss-of-Function Variants Cause Autosomal-Recessive Wiedemann-Rautenstrauch Syndrome.

Am J Hum Genet 2018 12 7;103(6):968-975. Epub 2018 Nov 7.

Division of Nutrition Metabolic Diseases, Department of Internal Medicine, Center for Human Nutrition, University of Texas Southwestern Medical Center, Dallas, TX 75390, USA. Electronic address:

Wiedemann-Rautenstrauch syndrome (WRS), also known as neonatal progeroid syndrome, is a rare disorder of unknown etiology. It has been proposed to be autosomal-recessive and is characterized by variable clinical features, such as intrauterine growth restriction and poor postnatal weight gain, characteristic facial features (triangular appearance to the face, convex nasal profile or pinched nose, and small mouth), widened fontanelles, pseudohydrocephalus, prominent scalp veins, lipodystrophy, and teeth abnormalities. A previous report described a single WRS patient with bi-allelic truncating and splicing variants in POLR3A. Here we present seven additional infants, children, and adults with WRS and bi-allelic truncating and/or splicing variants in POLR3A. POLR3A, the largest subunit of RNA polymerase III, is a DNA-directed RNA polymerase that transcribes many small noncoding RNAs that regulate transcription, RNA processing, and translation. Bi-allelic missense variants in POLR3A have been associated with phenotypes distinct from WRS: hypogonadotropic hypogonadism and hypomyelinating leukodystrophy with or without oligodontia. Our findings confirm the association of bi-allelic POLR3A variants with WRS, expand the clinical phenotype of WRS, and suggest specific POLR3A genotypes associated with WRS and hypomyelinating leukodystrophy.
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http://dx.doi.org/10.1016/j.ajhg.2018.10.010DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6288318PMC
December 2018

FARS2 deficiency; new cases, review of clinical, biochemical, and molecular spectra, and variants interpretation based on structural, functional, and evolutionary significance.

Mol Genet Metab 2018 11 29;125(3):281-291. Epub 2018 Jul 29.

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

An increasing number of mitochondrial diseases are found to be caused by pathogenic variants in nuclear encoded mitochondrial aminoacyl-tRNA synthetases. FARS2 encodes mitochondrial phenylalanyl-tRNA synthetase (mtPheRS) which transfers phenylalanine to its cognate tRNA in mitochondria. Since the first case was reported in 2012, a total of 21 subjects with FARS2 deficiency have been reported to date with a spectrum of disease severity that falls between two phenotypes; early onset epileptic encephalopathy and a less severe phenotype characterized by spastic paraplegia. In this report, we present an additional 15 individuals from 12 families who are mostly Arabs homozygous for the pathogenic variant Y144C, which is associated with the more severe early onset phenotype. The total number of unique pathogenic FARS2 variants known to date is 21 including three different partial gene deletions reported in four individuals. Except for the large deletions, all variants but two (one in-frame deletion of one amino acid and one splice-site variant) are missense. All large deletions and the single splice-site variant are in trans with a missense variant. This suggests that complete loss of function may be incompatible with life. In this report, we also review structural, functional, and evolutionary significance of select FARS2 pathogenic variants reported here.
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http://dx.doi.org/10.1016/j.ymgme.2018.07.014DOI Listing
November 2018

Phenotypic spectrum of Au-Kline syndrome: a report of six new cases and review of the literature.

Eur J Hum Genet 2018 09 14;26(9):1272-1281. Epub 2018 Jun 14.

Department of Medical Genetics, University of Calgary, Cumming School of Medicine, Calgary, AB, Canada.

Au-Kline syndrome (AKS, OMIM 616580) is a multiple malformation syndrome, first reported in 2015, associated with intellectual disability. AKS has been associated with de novo loss-of-function variants in HNRNPK (heterogeneous ribonucleoprotein K), and to date, only four of these patients have been described in the literature. Recently, an additional patient with a missense variant in HNRNPK was also reported. These patients have striking facial dysmorphic features, including long palpebral fissures, ptosis, deeply grooved tongue, broad nose, and down-turned mouth. Patients frequently also have skeletal and connective tissue anomalies, craniosynostosis, congenital heart malformations, and renal anomalies. In this report, we describe six new patients and review the clinical information on all reported AKS patients, further delineating the phenotype of AKS. There are now a total of 9 patients with de novo loss-of-function variants in HNRNPK, one individual with a de novo missense variant in addition to 3 patients with de novo deletions of 9q21.32 that encompass HNRNPK. While there is considerable overlap between AKS and Kabuki syndrome (KS), these additional patients demonstrate that AKS does have a distinct facial gestalt and phenotype that can be differentiated from KS. This growing AKS patient cohort also informs an emerging approach to management and health surveillance for these patients.
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http://dx.doi.org/10.1038/s41431-018-0187-2DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6117294PMC
September 2018

Developmental Trajectories of Executive and Verbal Processes in Children with Phenylketonuria.

Dev Neuropsychol 2018 12;43(3):207-218. Epub 2018 Feb 12.

a Department of Psychological & Brain Sciences , Washington University , St. Louis , Missouri , United States of America.

Phenylketonuria (PKU) is a hereditary disorder characterized by disrupted phenylalanine metabolism and cognitive impairment. However, the precise nature and developmental trajectory of this cognitive impairment remains unclear. The present study used a verbal fluency task to dissociate executive and verbal processes in children with PKU (n = 23; 7-18 years) and controls (n = 44; 7-19 years). Data were collected at three longitudinal timepoints over a three-year period, and the contributions of age, group, and their interaction to fluency performance were evaluated. Results indicated impairments in executive processes in children with PKU, which were exacerbated by declining metabolic control.
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http://dx.doi.org/10.1080/87565641.2018.1438439DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5902806PMC
June 2018

Cantu syndrome-associated SUR2 (ABCC9) mutations in distinct structural domains result in K channel gain-of-function by differential mechanisms.

J Biol Chem 2018 02 22;293(6):2041-2052. Epub 2017 Dec 22.

From the Departments of Cell Biology and Physiology and

The complex disorder Cantu syndrome (CS) arises from gain-of-function mutations in either or , the genes encoding the Kir6.1 and SUR2 subunits of ATP-sensitive potassium (K) channels, respectively. Recent reports indicate that such mutations can increase channel activity by multiple molecular mechanisms. In this study, we determined the mechanism by which K function is altered by several substitutions in distinct structural domains of SUR2: D207E in the intracellular L0-linker and Y985S, G989E, M1060I, and R1154Q/R1154W in TMD2. We engineered substitutions at their equivalent positions in rat SUR2A (D207E, Y981S, G985E, M1056I, and R1150Q/R1150W) and investigated functional consequences using macroscopic rubidium (Rb) efflux assays and patch-clamp electrophysiology. Our results indicate that D207E increases K channel activity by increasing intrinsic stability of the open state, whereas the cluster of Y981S/G985E/M1056I substitutions, as well as R1150Q/R1150W, augmented Mg-nucleotide activation. We also tested the responses of these channel variants to inhibition by the sulfonylurea drug glibenclamide, a potential pharmacotherapy for CS. None of the D207E, Y981S, G985E, or M1056I substitutions had a significant effect on glibenclamide sensitivity. However, Gln and Trp substitution at Arg-1150 significantly decreased glibenclamide potency. In summary, these results provide additional confirmation that mutations in CS-associated SUR2 mutations result in K gain-of-function. They help link CS genotypes to phenotypes and shed light on the underlying molecular mechanisms, including consequences for inhibitory drug sensitivity, insights that may inform the development of therapeutic approaches to manage CS.
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http://dx.doi.org/10.1074/jbc.RA117.000351DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5808765PMC
February 2018

De Novo Mutations in Protein Kinase Genes CAMK2A and CAMK2B Cause Intellectual Disability.

Am J Hum Genet 2017 Nov;101(5):768-788

Nottingham Regional Genetics Service, City Hospital Campus, Nottingham University Hospitals NHS Trust, The Gables, Hucknall Road, Nottingham NG5 1PB, UK.

Calcium/calmodulin-dependent protein kinase II (CAMK2) is one of the first proteins shown to be essential for normal learning and synaptic plasticity in mice, but its requirement for human brain development has not yet been established. Through a multi-center collaborative study based on a whole-exome sequencing approach, we identified 19 exceedingly rare de novo CAMK2A or CAMK2B variants in 24 unrelated individuals with intellectual disability. Variants were assessed for their effect on CAMK2 function and on neuronal migration. For both CAMK2A and CAMK2B, we identified mutations that decreased or increased CAMK2 auto-phosphorylation at Thr286/Thr287. We further found that all mutations affecting auto-phosphorylation also affected neuronal migration, highlighting the importance of tightly regulated CAMK2 auto-phosphorylation in neuronal function and neurodevelopment. Our data establish the importance of CAMK2A and CAMK2B and their auto-phosphorylation in human brain function and expand the phenotypic spectrum of the disorders caused by variants in key players of the glutamatergic signaling pathway.
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http://dx.doi.org/10.1016/j.ajhg.2017.10.003DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5673671PMC
November 2017

Phenotypic and molecular characterisation of CDK13-related congenital heart defects, dysmorphic facial features and intellectual developmental disorders.

Genome Med 2017 08 14;9(1):73. Epub 2017 Aug 14.

Department of Molecular and Human Genetics, Baylor College of Medicine, 6701 Fannin St, Suite 1560, Houston, TX, 77030, USA.

Background: De novo missense variants in CDK13 have been described as the cause of syndromic congenital heart defects in seven individuals ascertained from a large congenital cardiovascular malformations cohort. We aimed to further define the phenotypic and molecular spectrum of this newly described disorder.

Methods: To minimise ascertainment bias, we recruited nine additional individuals with CDK13 pathogenic variants from clinical and research exome laboratory sequencing cohorts. Each individual underwent dysmorphology exam and comprehensive medical history review.

Results: We demonstrate greater than expected phenotypic heterogeneity, including 33% (3/9) of individuals without structural heart disease on echocardiogram. There was a high penetrance for a unique constellation of facial dysmorphism and global developmental delay, as well as less frequently seen renal and sacral anomalies. Two individuals had novel CDK13 variants (p.Asn842Asp, p.Lys734Glu), while the remaining seven unrelated individuals had a recurrent, previously published p.Asn842Ser variant. Summary of all variants published to date demonstrates apparent restriction of pathogenic variants to the protein kinase domain with clustering in the ATP and magnesium binding sites.

Conclusions: Here we provide detailed phenotypic and molecular characterisation of individuals with pathogenic variants in CDK13 and propose management guidelines based upon the estimated prevalence of anomalies identified.
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http://dx.doi.org/10.1186/s13073-017-0463-8DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5557075PMC
August 2017
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