Publications by authors named "Dagmar Huhle"

8 Publications

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Novel pericentric inversion inv(9)(p23q22.3) in unrelated individuals with fertility problems in the Southeast European population.

J Hum Genet 2020 Sep 13;65(9):783-795. Epub 2020 May 13.

Department of Genetics and Molecular Biology, Bioiatriki Healthcare Group, Athens, Greece.

Pericentric inversions are among the known polymorphisms detected in the general population at a frequency of 1-2%. Despite their generally benign nature, pericentric inversions affect the reproductive potential of carriers by increasing the risk for unbalanced live-born offspring, miscarriages, or other fertility problems. Here we present a novel large pericentric inversion of chromosome 9, inv(9)(p23q22.3), detected in 30 heterozygote carriers, 24 from seven apparently unrelated families and 6 isolated patients, where the probands were mainly referred for fertility and prenatal problems. The inversion carries a significant risk for recombinant abnormal chromosomes, as in two families one supernumerary rec(9)dup(9p) and one rec(9)dup(9q) were identified, leading to neonatal death and miscarriage, respectively. The inversion carriers were identified by three different laboratories in Greece, Cyprus and Germany respectively, however all carriers have Southeast European origin. The inversion appears to be more frequent in the Greek population, as the majority of the carriers were identified in Greece. We were able to determine that the inversion is identical in all individuals included in the study by applying a combination of several methodologies, such as karyotype, fluorescence in situ hybridization (FISH), chromosomal microarrays (CMA) and haplotype analysis. In addition, haplotype analysis supports that the present inversion is identical by descent (IBD) inherited from a single common ancestor. Our results are, therefore, highly indicative of a founder effect of this inversion, presumably reflecting an event that was present in a small number of individuals that migrated to the current Southeast Europe/Northern Greece from a larger population.
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http://dx.doi.org/10.1038/s10038-020-0769-zDOI Listing
September 2020

Childhood Dystonia-Parkinsonism Following Infantile Spasms-Clinical Clue to Diagnosis in Early Beta-Propeller Protein-Associated Neurodegeneration.

Neuropediatrics 2020 02 10;51(1):22-29. Epub 2019 Sep 10.

Department of Pediatric Neurology, Leipzig University Hospital for Children and Adolescents, Leipzig, Sachsen, Germany.

Introduction: Beta-propeller protein-associated neurodegeneration (BPAN) is a very rare, X-linked dominant (XLD) inherited member of the neurodegeneration with brain iron accumulation (NBIA) disease family.

Case Report: We present a female case of BPAN with infantile spasms in the first year, Rett-like symptomatology, focal epilepsy, and loss of motor skills in childhood. Menarche occurred at the age of 9, after precocious pubarche and puberty.Dystonia-parkinsonism as extrapyramidal sign at the age of 10 years resulted in radiological and genetic work-up.

Results: Burke-Fahn-Marsden Dystonia Rating Scale (BFMDRS) measured 66/120 points in body part-related dystonia symptoms. Cerebrospinal fluid examination showed dopamine depletion.T2 and B0 sequences of the diffusion-weighted magnetic resonance imaging showed susceptibility artifacts with NBIA-typical hypointense globus pallidus (GP) and substantia nigra (SN). Next-generation sequencing revealed a BPAN-causing pathogenic variant in gene (c.830 + 1G > A, XLD, heterozygous, de novo). Skewed X-inactivation was measured (2:98).

Conclusions: Autophagy-related X-linked BPAN disease might still be underdiagnosed in female cases of infantile spasms.Skewed X-inactivation will have mainly influenced the uncommon, very early childhood neurodegenerative symptomatology in the present BPAN case. Oral levodopa substitution led to improvement in sleep disorder, hypersalivation, and swallowing.Reduced white matter and hypointense signals in SN and GP on susceptibility sequences in magnetic resonance imaging are characteristic radiological findings of advanced disease in NBIA. No BPAN-typical halo sign in T1-weighted scan at midbrain level was seen at the age of 11 years. NBIA panel is recommended for early diagnosis.
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http://dx.doi.org/10.1055/s-0039-1696688DOI Listing
February 2020

Mutations in ACTL6B Cause Neurodevelopmental Deficits and Epilepsy and Lead to Loss of Dendrites in Human Neurons.

Am J Hum Genet 2019 05 25;104(5):815-834. Epub 2019 Apr 25.

Department of Molecular Neuroscience, UCL Institute of Neurology, Queen Square, WC1N 3BG London, UK.

We identified individuals with variations in ACTL6B, a component of the chromatin remodeling machinery including the BAF complex. Ten individuals harbored bi-allelic mutations and presented with global developmental delay, epileptic encephalopathy, and spasticity, and ten individuals with de novo heterozygous mutations displayed intellectual disability, ambulation deficits, severe language impairment, hypotonia, Rett-like stereotypies, and minor facial dysmorphisms (wide mouth, diastema, bulbous nose). Nine of these ten unrelated individuals had the identical de novo c.1027G>A (p.Gly343Arg) mutation. Human-derived neurons were generated that recaptured ACTL6B expression patterns in development from progenitor cell to post-mitotic neuron, validating the use of this model. Engineered knock-out of ACTL6B in wild-type human neurons resulted in profound deficits in dendrite development, a result recapitulated in two individuals with different bi-allelic mutations, and reversed on clonal genetic repair or exogenous expression of ACTL6B. Whole-transcriptome analyses and whole-genomic profiling of the BAF complex in wild-type and bi-allelic mutant ACTL6B neural progenitor cells and neurons revealed increased genomic binding of the BAF complex in ACTL6B mutants, with corresponding transcriptional changes in several genes including TPPP and FSCN1, suggesting that altered regulation of some cytoskeletal genes contribute to altered dendrite development. Assessment of bi-alleic and heterozygous ACTL6B mutations on an ACTL6B knock-out human background demonstrated that bi-allelic mutations mimic engineered deletion deficits while heterozygous mutations do not, suggesting that the former are loss of function and the latter are gain of function. These results reveal a role for ACTL6B in neurodevelopment and implicate another component of chromatin remodeling machinery in brain disease.
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http://dx.doi.org/10.1016/j.ajhg.2019.03.022DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6507050PMC
May 2019

Clinical and genetic spectrum of AMPD2-related pontocerebellar hypoplasia type 9.

Eur J Hum Genet 2018 05 20;26(5):695-708. Epub 2018 Feb 20.

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

Pontocerebellar hypoplasia (PCH) represents a group of autosomal-recessive progressive neurodegenerative disorders of prenatal onset. Eleven PCH subtypes are classified according to clinical, neuroimaging and genetic findings. Individuals with PCH type 9 (PCH9) have a unique combination of postnatal microcephaly, hypoplastic cerebellum and pons, and hypoplastic or absent corpus callosum. PCH9 is caused by biallelic variants in AMPD2 encoding adenosine monophosphate deaminase 2; however, a homozygous AMPD2 frameshift variant has recently been reported in two family members with spastic paraplegia type 63 (SPG63). We identified homozygous or compound heterozygous AMPD2 variants in eight PCH-affected individuals from six families. The eight variants likely affect function and comprise one frameshift, one nonsense and six missense variants; seven of which were novel. The main clinical manifestations in the eight new patients and 17 previously reported individuals with biallelic AMPD2 variants were postnatal microcephaly, severe global developmental delay, spasticity, and central visual impairment. Brain imaging data identified hypomyelination, hypoplasia of the cerebellum and pons, atrophy of the cerebral cortex, complete or partial agenesis of the corpus callosum and the "figure 8" shape of the hypoplastic midbrain as consistent features. We broaden the AMPD2-related clinical spectrum by describing one individual without microcephaly and absence of the characteristic "figure 8" shape of the midbrain. The existence of various AMPD2 isoforms with different functions possibly explains the variability in phenotypes associated with AMPD2 variants: variants leaving some of the isoforms intact may cause SPG63, while those affecting all isoforms may result in the severe and early-onset PCH9.
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http://dx.doi.org/10.1038/s41431-018-0098-2DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5945775PMC
May 2018

Next-generation sequencing reveals the mutational landscape of clinically diagnosed Usher syndrome: copy number variations, phenocopies, a predominant target for translational read-through, and mutated in Heimler syndrome.

Mol Genet Genomic Med 2017 Sep 6;5(5):531-552. Epub 2017 Jul 6.

Bioscientia Center for Human GeneticsIngelheimGermany.

Background: Combined retinal degeneration and sensorineural hearing impairment is mostly due to autosomal recessive Usher syndrome (USH1: congenital deafness, early retinitis pigmentosa (RP); USH2: progressive hearing impairment, RP).

Methods: Sanger sequencing and NGS of 112 genes (Usher syndrome, nonsyndromic deafness, overlapping conditions), MLPA, and array-CGH were conducted in 138 patients clinically diagnosed with Usher syndrome.

Results: A molecular diagnosis was achieved in 97% of both USH1 and USH2 patients, with biallelic mutations in 97% (USH1) and 90% (USH2), respectively. Quantitative readout reliably detected CNVs (confirmed by MLPA or array-CGH), qualifying targeted NGS as one tool for detecting point mutations and CNVs. CNVs accounted for 10% of identified alleles, often to seemingly monoallelic point mutations. We demonstrate PTC124-induced read-through of the common p.Trp3955* nonsense mutation (13% of detected alleles), a potential therapy target. Usher gene mutations were found in most patients with atypical Usher syndrome, but the diagnosis was adjusted in case of double homozygosity for mutations in and , genes implicated in isolated deafness and RP. Two patients with additional enamel dysplasia had biallelic mutations, for the first time linking this gene to Heimler syndrome.

Conclusion: Targeted NGS not restricted to Usher genes proved beneficial in uncovering conditions mimicking Usher syndrome.
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http://dx.doi.org/10.1002/mgg3.312DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5606877PMC
September 2017

FOXG1 syndrome: genotype-phenotype association in 83 patients with FOXG1 variants.

Genet Med 2018 01 29;20(1):98-108. Epub 2017 Jun 29.

CeGaT, Tübingen, Germany.

PurposeThe study aimed at widening the clinical and genetic spectrum and assessing genotype-phenotype associations in FOXG1 syndrome due to FOXG1 variants.MethodsWe compiled 30 new and 53 reported patients with a heterozygous pathogenic or likely pathogenic variant in FOXG1. We grouped patients according to type and location of the variant. Statistical analysis of molecular and clinical data was performed using Fisher's exact test and a nonparametric multivariate test.ResultsAmong the 30 new patients, we identified 19 novel FOXG1 variants. Among the total group of 83 patients, there were 54 variants: 20 frameshift (37%), 17 missense (31%), 15 nonsense (28%), and 2 in-frame variants (4%). Frameshift and nonsense variants are distributed over all FOXG1 protein domains; missense variants cluster within the conserved forkhead domain. We found a higher phenotypic variability than previously described. Genotype-phenotype association revealed significant differences in psychomotor development and neurological features between FOXG1 genotype groups. More severe phenotypes were associated with truncating FOXG1 variants in the N-terminal domain and the forkhead domain (except conserved site 1) and milder phenotypes with missense variants in the forkhead conserved site 1.ConclusionsThese data may serve for improved interpretation of new FOXG1 sequence variants and well-founded genetic counseling.
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http://dx.doi.org/10.1038/gim.2017.75DOI Listing
January 2018

Mitotic stability of small supernumerary marker chromosomes: a study based on 93 immortalized cell lines.

Cytogenet Genome Res 2014 1;142(3):151-60. Epub 2014 Apr 1.

Institute of Human Genetics, Jena University Hospital, Friedrich Schiller University, Jena, Germany.

Small supernumerary marker chromosomes (sSMC) are known for being present in mosaic form as 47,+mar/46 in >50% of the cases with this kind of extra chromosomes. However, no detailed studies have been done for the mitotic stability of sSMC so far, mainly due to the lack of a corresponding in vitro model system. Recently, we established an sSMC-cell bank (Else Kröner-Fresenius-sSMC-cellbank) with >150 cell lines. Therefore, 93 selected sSMC cases were studied here for the presence of the corresponding marker chromosomes before and after Epstein-Barr virus-induced immortalization. The obtained results showed that dicentric inverted duplicated-shaped sSMC are by far more stable in vitro than monocentric centric minute- or ring-shaped sSMC. Simultaneously, a review of the literature revealed that a comparable shape-dependent mitotic stability can be found in vivo in sSMC carriers. Additionally, a possible impact of the age of the sSMC carrier on mitotic stability was found: sSMC cell lines established from patients between 10-20 years of age were predominantly mitotically unstable. The latter finding was independent of the sSMC shape. The present study shows that in vitro models can lead to new and exciting insights into the biology of this genetically and clinically heterogeneous patient group.
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http://dx.doi.org/10.1159/000360776DOI Listing
July 2014

Clinical, cytogenetic and molecular investigation in a fetus with Wolf-Hirschhorn syndrome with paternally derived 4p deletion. Case report and review of the literature.

Fetal Diagn Ther 2004 May-Jun;19(3):251-60

Institute of Clinical Genetics, Philipps University, Marburg, Germany.

Wolf-Hirschhorn (4p-) syndrome (WHS), caused by partial deletion of the short arm of chromosome 4, has been extensively described in children and young adults. Knowledge on fetuses with WHS is still limited due to the small number of published cases. We report on a fetus with prenatally diagnosed severe intrauterine growth retardation, reduced thoracal diameter, clubfeet deformity and midface hypoplasia including slight microretrognathia indicative for fetal karyotyping. Chromosome analysis after amniocentesis revealed a de novo terminal deletion of chromosome 4p [karyotype: 46,XX,del(4) (p16)] which was confirmed by FISH. Analyses of a set of polymorphic markers mapping in 4pter->4p15.3 showed absence of paternal haplotypes. These observations corroborate the preferential paternal origin of the de novo 4p deletion in WHS patients. Furthermore, the distal breakpoint could be narrowed to band 4p16.1. At autopsy, the fetus showed typical craniofacial dysmorphic signs of WHS, severe IUGR and delayed bone age. This report suggests the possibility of recognising the particular phenotype of WHS in utero by prenatal ultrasound and emphasises the importance of karyotyping fetuses with severe IUGR, especially when the amount of amniotic fluid is normal.
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http://dx.doi.org/10.1159/000076707DOI Listing
November 2004
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