Epidemiology of inherited epidermolysis bullosa in Germany.

BACKGROUND: Epidermolysis bullosa (EB) is a rare genetic disorder manifesting with skin and mucosal membrane blistering in different degrees of severity. OBJECTIVE: Epidemiological data from different countries have been published, but none are available from Germany. METHODS: In this population-based cross-sectional study, people living with EB in Germany were identified using the following sources: academic hospitals, diagnostic laboratories and patient organization. RESULTS: Our study indicates an overall EB incidence of 45 per million live births in Germany. With 14.23 per million live births for junctional EB, the incidence is higher than in other countries, possibly reflecting the availability of early molecular genetic diagnostics in severely affected neonates. Dystrophic EB was assessed at 15.58 cases per million live births. The relatively low incidence found for EB simplex, 14.93 per million live births, could be explained by late or missed diagnosis, but also by 33% of cases remaining not otherwise specified. Using log-linear models, we estimated a prevalence of 54 per million for all EB types, 2.44 for junctional EB, 12.16 for dystrophic EB and 28.44 per million for EB simplex. These figures are comparable to previously reported data from other countries. CONCLUSIONS: Altogether, there are at least 2000 patients with EB in the German population. These results should support national policies and pharmaceutical companies in decision-making, allow more precise planning of drug development and clinical trials, and aid patient advocacy groups in their effort to improve quality of life of people with this orphan disease.

ANKRD11 variants: KBG syndrome and beyond.

Mutations affecting the transcriptional regulator Ankyrin Repeat Domain 11 (ANKRD11) are mainly associated with the multisystem developmental disorder known as KBG syndrome, but have also been identified in individuals with Cornelia de Lange syndrome (CdLS) and other developmental disorders caused by variants affecting different chromatin regulators. The extensive functional overlap of these proteins results in shared phenotypical features, which complicate the assessment of the clinical diagnosis. Additionally, re-evaluation of individuals at a later age occasionally reveals that the initial phenotype has evolved toward clinical features more reminiscent of a developmental disorder different from the one that was initially diagnosed. For this reason, variants in ANKRD11 can be ascribed to a broader class of disorders that fall within the category of the so-called chromatinopathies. In this work, we report on the clinical characterization of 23 individuals with variants in ANKRD11. The subjects present primarily with developmental delay, intellectual disability and dysmorphic features, and all but two received an initial clinical diagnosis of either KBG syndrome or CdLS. The number and the severity of the clinical signs are overlapping but variable and result in a broad spectrum of phenotypes, which could be partially accounted for by the presence of additional molecular diagnoses and distinct pathogenic mechanisms.

Chondrodysplasia and growth failure in children after early hematopoietic stem cell transplantation for non-oncologic disorders.

Bone dysplasias (osteochondrodysplasias) are a large group of conditions associated with short stature, skeletal disproportion, and radiographic abnormalities of skeletal elements. Nearly all are genetic in origin. We report a series of seven children with similar findings of chondrodysplasia and growth failure following early hematopoietic stem cell transplantation (HSCT) for pediatric non-oncologic disease: hemophagocytic lymphohistiocytosis or HLH (five children, three with biallelic HLH-associated variants [in PRF1 and UNC13D] and one with HLH secondary to visceral Leishmaniasis), one child with severe combined immunodeficiency and one with Omenn syndrome (both children had biallelic RAG1 pathogenic variants). All children had normal growth and no sign of chondrodysplasia at birth and prior to their primary disease. After HSCT, all children developed growth failure, with standard deviation scores for height at or below -3. Radiographically, all children had changes in the spine, metaphyses and epiphyses, compatible with a spondyloepimetaphyseal dysplasia. Genomic sequencing failed to detect pathogenic variants in genes associated with osteochondrodysplasias. We propose that such chondrodysplasia with growth failure is a novel, rare, but clinically important complication following early HSCT for non-oncologic pediatric diseases. The pathogenesis is unknown but could possibly involve loss or perturbation of the cartilage-bone stem cell population.

Genetics of intellectual disability in consanguineous families.

Autosomal recessive (AR) gene defects are the leading genetic cause of intellectual disability (ID) in countries with frequent parental consanguinity, which account for about 1/7th of the world population. Yet, compared to autosomal dominant de novo mutations, which are the predominant cause of ID in Western countries, the identification of AR-ID genes has lagged behind. Here, we report on whole exome and whole genome sequencing in 404 consanguineous predominantly Iranian families with two or more affected offspring. In 219 of these, we found likely causative variants, involving 77 known and 77 novel AR-ID (candidate) genes, 21 X-linked genes, as well as 9 genes previously implicated in diseases other than ID. This study, the largest of its kind published to date, illustrates that high-throughput DNA sequencing in consanguineous families is a superior strategy for elucidating the thousands of hitherto unknown gene defects underlying AR-ID, and it sheds light on their prevalence.

Paternally Inherited IGF2 Mutation and Growth Restriction.

In humans, mutations in IGF1 or IGF1R cause intrauterine and postnatal growth restriction; however, data on mutations in IGF2, encoding insulin-like growth factor (IGF) II, are lacking. We report an IGF2 variant (c.191C→A, p.Ser64Ter) with evidence of pathogenicity in a multigenerational family with four members who have growth restriction. The phenotype affects only family members who have inherited the variant through paternal transmission, a finding that is consistent with the maternal imprinting status of IGF2. The severe growth restriction in affected family members suggests that IGF-II affects postnatal growth in addition to prenatal growth. Furthermore, the dysmorphic features of affected family members are consistent with a role of deficient IGF-II levels in the cause of the Silver-Russell syndrome. (Funded by Bundesministerium für Bildung und Forschung and the European Union.).

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

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.

Continuing role for classical cytogenetics: Case report of a boy with ring syndrome caused by complete ring chromosome 4 and review of literature.

Constitutional ring chromosomes can be found for all human chromosomes and are very rare chromosomal abnormalities. A complete ring chromosome without loss of genetic material results from fusion of subtelomeric regions or telomere-telomere fusion. In cases of complete ring chromosome, an increased incidence of severe growth failure with no or only minor anomalies has been observed and attributed to ring syndrome. Ring syndrome is thought to be caused by "dynamic mosaicism" due to ring instability. We report a 6-year-old boy with de novo ring chromosome 4 and typical characteristics of the ring syndrome, namely, proportionate severe growth failure, microcephaly, and minor anomalies. Cytogenetic studies showed complete ring chromosome 4 with mitotic instability. Microarray gave normal results, thus excluding the loss of detectable genetic material. The literature of complete ring chromosome 4 is reviewed. Our case report supports the theory of ring syndrome. No studies about the effects and possible side effects of growth hormone therapy on patients with ring chromosomes have yet been published. We suggest that cytogenetic monitoring of the rate of secondary aberrations in patients with ring chromosome undergoing growth hormone therapy might be feasible. Since the diagnosis would have been missed by molecular karyotyping, our case report underlines the continuing role of classical cytogenetics for the evaluation of structural chromosomal abnormalities in patients with mental and/or physical anomalies. Standard karyotyping is still indispensable and should have an ongoing role as first-tier analysis together with molecular karyotyping. © 2017 Wiley Periodicals, Inc.

Menkes disease with discordant phenotype in female monozygotic twins.

Menkes disease (MD) is a rare X-linked recessive disorder caused by mutations in the ATP7A gene. This neurodegenerative disorder typically affects males and is characterized by impaired copper distribution and the malfunction of several copper-dependent enzymes. We report clinically discordant female monozygotic twins (MZT) with a heterozygous ATP7A mutation. One twin girl is healthy at the current age of 4 years, whereas the other twin girl developed classical MD, showed disease stabilization under copper histidine treatment but died at the age of 3 years. Presumably, the affected girl developed MD due to skewed X inactivation, although this could not be demonstrated in two tissues (blood, buccal mucosa). This case is a rare example of an affected girl with MD and shows the possibility of a discordant phenotype in MZT girls. As speculated in other X-linked diseases, the process of monozygotic twinning may be associated with skewed X inactivation leading to a discordant phenotype.

Microduplication of 3p26.3 in nonsyndromic intellectual disability indicates an important role of CHL1 for normal cognitive function.

Terminal deletions of chromosome 3p26.3 confined to the CHL1 gene have previously been described in children with intellectual disability and epilepsy. Here, we report for the first time, a 3p26.3 duplication including only the CHL1 gene in an intellectually disabled girl with epilepsy. The penetrance of both deletions and duplications in 3p26.3 is reduced because all chromosomal imbalances were inherited from healthy parents. Further studies are needed to specify the pathogenic mechanism of 3p26.3 imbalances and to estimate recurrence risks in genetic counseling. However, the description of both deletions and duplications of chromosome 3p26.3 in nonsyndromic intellectual disability suggests that CHL1 is a dosage-sensitive gene with an important role for normal cognitive development.

A 16q12 microdeletion in a boy with severe psychomotor delay, craniofacial dysmorphism, brain and limb malformations, and a heart defect.

Interstitial deletions of the proximal chromosome 16q are rare. To date, only six cases with molecularly well-characterized microdeletions within this chromosomal region have been described. We report on a patient with severe psychomotor delay, dysmorphic features, microcephaly and hypoplasia of the corpus callosum, epilepsy, a heart defect, and pronounced muscular hypotonia. Array comparative genomic hybridization (aCGH) revealed that the patient's features were likely caused by a 4.7 Mb de novo deletion on chromosome 16q12.1q12.2, which was confirmed by quantitative real-time PCR (qPCR). The psychomotor delay and craniofacial dysmorphism are more severe in our patient than previously reported patients. Unmasked recessive mutations in the ZNF423 and FTO genes on the remaining allele were excluded as the putative cause for this severe phenotype. In conclusion, the phenotypic spectrum of microdeletions in 16q12 is broad and comprises variable degrees of psychomotor delay and intellectual disability, craniofacial anomalies, and additional features, including heart defects, brain malformations, and limb anomalies.

Phenotypic spectrum associated with CASK loss-of-function mutations.

BACKGROUND: Heterozygous mutations in the CASK gene in Xp11.4 have been shown to be associated with a distinct brain malformation phenotype in females, including disproportionate pontine and cerebellar hypoplasia. METHODS: The study characterised the CASK alteration in 20 new female patients by molecular karyotyping, fluorescence in situ hybridisation, sequencing, reverse transcriptase (RT) and/or quantitative real-time PCR. Clinical and brain imaging data of a total of 25 patients were reviewed. RESULTS: 11 submicroscopic copy number alterations, including nine deletions of ~11 kb to 4.5 Mb and two duplications, all covering (part of) CASK, four splice, four nonsense, and one 1 bp deletion are reported. These heterozygous CASK mutations most likely lead to a null allele. Brain imaging consistently showed diffuse brainstem and cerebellar hypoplasia with a dilated fourth ventricle, but of remarkably varying degrees. Analysis of 20 patients in this study, and five previously reported patients, revealed a core clinical phenotype comprising severe developmental delay/intellectual disability, severe postnatal microcephaly, often associated with growth retardation, (axial) hypotonia with or without hypertonia of extremities, optic nerve hypoplasia, and/or other eye abnormalities. A recognisable facial phenotype emerged, including prominent and broad nasal bridge and tip, small or short nose, long philtrum, small chin, and/or large ears. CONCLUSIONS: These findings define the phenotypic spectrum associated with CASK loss-of-function mutations. The combination of developmental and brain imaging features together with mild facial dysmorphism is highly suggestive of this disorder and should prompt subsequent testing of the CASK gene.

CADA: phenotype-driven gene prioritization based on a case-enriched knowledge graph.

Many rare syndromes can be well described and delineated from other disorders by a combination of characteristic symptoms. These phenotypic features are best documented with terms of the Human Phenotype Ontology (HPO), which are increasingly used in electronic health records (EHRs), too. Many algorithms that perform HPO-based gene prioritization have also been developed; however, the performance of many such tools suffers from an over-representation of atypical cases in the medical literature. This is certainly the case if the algorithm cannot handle features that occur with reduced frequency in a disorder. With Cada, we built a knowledge graph based on both case annotations and disorder annotations. Using network representation learning, we achieve gene prioritization by link prediction. Our results suggest that Cada exhibits superior performance particularly for patients that present with the pathognomonic findings of a disease. Additionally, information about the frequency of occurrence of a feature can readily be incorporated, when available. Crucial in the design of our approach is the use of the growing amount of phenotype-genotype information that diagnostic labs deposit in databases such as ClinVar. By this means, Cada is an ideal reference tool for differential diagnostics in rare disorders that can also be updated regularly.

Disorders Caused by Genetic Mosaicism.

BACKGROUND: Genetic mosaics arise through new mutations occurring after fertiliza- tion (i.e., postzygotic mutations). Mosaics have been described in recent years as the cause of many different disorders; many of these are neurocutaneous diseases and syndromal developmental disorders, each with a characteristic phenotype. In some of these disorders, there is a genetic predisposition to the development of tumors. This article is intended as an overview of selected mosaic diseases. METHODS: This review is based on publications retrieved by a selective search in PubMed, with particular attention to recent articles in high-ranking journals dealing with asymmetric growth disturbances, focal brain malformations, mosaic diseases due to dysregulation of the RAS/RAF signaling pathway (mosaic RASopathies), and vascular malformations. RESULTS: The identification of postzygotic mutations has led to the reclassification of traditional disease entities and to a better understanding of their pathogenesis. Diagnosis is aided by modern next-generation sequencing (NGS) techniques that allow the detection even of low-grade mosaics. Many mosaic mutations are not detectable in blood, but only in the affected tissue, e.g., the skin. Genetic mosaic diseases often manifest themselves in the skin and brain, and by facial dysmorphism, asymmetrical growth disturbances, and vascular malformations. CONCLUSION: The possibility of a mosaic disease should be kept in mind in the diag- nostic evaluation of patients with asymmetrical growth disturbances, focal neuronal migration disturbances, vascular malformations, and linear skin abnormalities. The demonstration of a postzygotic mutation often affords relief to the parents of an affected child, since this means that there is no increased risk for recurrence of the same disorder in future children. Correct classification is important, as molecular available for certain mosaic diseases, e.g., PIK3CA-related overgrowth spectrum (PROS) disorder.

The Phenotypic Spectrum of PRRT2-Associated Paroxysmal Neurologic Disorders in Childhood.

Pathogenic variants in PRRT2, encoding the proline-rich transmembrane protein 2, have been associated with an evolving spectrum of paroxysmal neurologic disorders. Based on a cohort of children with PRRT2-related infantile epilepsy, this study aimed at delineating the broad clinical spectrum of PRRT2-associated phenotypes in these children and their relatives. Only a few recent larger cohort studies are on record and findings from single reports were not confirmed so far. We collected detailed genetic and phenotypic data of 40 previously unreported patients from 36 families. All patients had benign infantile epilepsy and harbored pathogenic variants in PRRT2 (core cohort). Clinical data of 62 family members were included, comprising a cohort of 102 individuals (extended cohort) with PRRT2-associated neurological disease. Additional phenotypes in the cohort of patients with benign sporadic and familial infantile epilepsy consist of movement disorders with paroxysmal kinesigenic dyskinesia in six patients, infantile-onset movement disorders in 2 of 40 individuals, and episodic ataxia after mild head trauma in one girl with bi-allelic variants in PRRT2. The same girl displayed a focal cortical dysplasia upon brain imaging. Familial hemiplegic migraine and migraine with aura were reported in nine families. A single individual developed epilepsy with continuous spikes and waves during sleep. In addition to known variants, we report the novel variant c.843G>T, p.(Trp281Cys) that co-segregated with benign infantile epilepsy and migraine in one family. Our study highlights the variability of clinical presentations of patients harboring pathogenic PRRT2 variants and expands the associated phenotypic spectrum.

New prognostic markers revealed by evaluation of genes correlated with clinical parameters in Wilms tumors.

Current treatment protocols for Wilms tumor achieve 90% cure rates, but relapse risk and side effects from therapy remain challenging. Over the last decade, numerous markers have been proposed for classification and/or prediction of outcome. However, cohort sizes were quite variable and often small. We now provide a large-scale reassessment by real-time RT-PCR of 40 markers in 102 Wilms tumors followed by validation of potentially relevant markers in an independent set of 74 tumors. In the first data set, individual comparison with clinical data combined with adjustment for multiple testing and multivariate analysis revealed potentially relevant alteration of CA9, DKK1, EGR1, HEY2, MYC, MYCN, TERT, TOP2A, TRIM22, and VEGF expression in association with CTNNB1 mutation status, histological risk, response to chemotherapy, metastasis, relapse, or mortality. To further validate these data, potentially relevant genes for specific outcomes were reanalyzed in a second, independent tumor set. Here, univariate analysis confirmed the association of HEY2 with high-risk tumors and of TRIM22 with mortality. Even where significance levels could not be reached, the direction and extent of differential expression were generally reproducible. Multivariate analysis verified a weak correlation of TOP2A expression with metastasis and of TRIM22 with fatal outcome. Although we could corroborate only some of the previously reported associations of expression changes with clinical parameters, our results indicate that real-time RT-PCR analysis can facilitate further classification of Wilms tumor and prediction of outcome to adjust treatment accordingly. This article contains Supplementary Material available at http://www.interscience.wiley.com/jpages/1045-2257/suppmat.

Clinical report of 8 patients with 49,XXXXY syndrome: Delineation of the facial gestalt and depiction of the clinical spectrum.

49,XXXXY syndrome is a rare sex chromosome aneuploidy syndrome. Cognitive impairment with expressive language deficits in combination with developmental and speech dyspraxia are cardinal symptoms. Testicular insufficiency becomes apparent during adolescence. Neurological, musculoskeletal, genital, orthodontic and immunological anomalies are common and a higher incidence of congenital malformations has been described. Here we show the evolving clinical and facial phenotype of eight boys and men with 49,XXXXY, demonstrating an increasingly perceptible distinct facial gestalt over time. In addition, almost all patients had muscular hypotonia, radioulnar synostosis, white matter anomalies, fifth-finger clinodactyly, recurrent respiratory infections in early childhood and teeth anomalies. IQ scores ranged between 40 and 70. Though many boys showed short stature at some point in early childhood, most outgrew it. As more long term data of boys and men with 49,XXXXY become available, parents of affected boys can be counseled more specifically as to the expected course and spectrum of this rare chromosomal disorder. Moreover, the multidisciplinary support can be optimized und unnecessary diagnostics avoided.

Clinical long-time course, novel mutations and genotype-phenotype correlation in a cohort of 27 families with POMT1-related disorders.

BACKGROUND: The protein O-mannosyltransferase 1, encoded by the POMT1 gene, is a key enzyme in the glycosylation of α-dystroglycan. POMT1-related disorders belong to the group of dystroglycanopathies characterized by a proximally pronounced muscular dystrophy with structural or functional involvement of the brain and/or the eyes. The phenotypic spectrum ranges from the severe Walker-Warburg syndrome (WWS) to milder forms of limb girdle muscular dystrophy (LGMD). The phenotypic severity of POMT1-related dystroglycanopathies depends on the residual enzyme activity. A genotype-phenotype correlation can be assumed. RESULTS: The clinical, neuroradiological, and genetic findings of 35 patients with biallelic POMT1 mutations (15 WWS, 1 MEB (muscle-eye-brain disease), 19 LGMD) from 27 independent families are reported. The representative clinical course of an infant with WWS and the long-term course of a 32 years old patient with LGMD are described in more detail. Specific features of 15 patients with the homozygous founder mutation p.Ala200Pro are defined as a distinct and mildly affected LGMD subgroup. Ten previously reported and 8 novel POMT1 mutations were identified. Type and location of each of the POMT1 mutations are evaluated in detail and a list of all POMT1 mutations reported by now is provided. Patients with two mutations leading to premature protein termination had a WWS phenotype, while the presence of at least one missense mutation was associated with milder phenotypes. In the patient with MEB-like phenotype two missense mutations were observed within the catalytic active domain of the enzyme. CONCLUSIONS: Our large cohort confirms the importance of type and location of each POMT1 mutation for the individual clinical manifestation and thereby expands the knowledge on the genotype-phenotype correlation in POMT1-related dystroglycanopathies. This genotype-phenotype correlation is further supported by the observation of an intrafamiliar analogous clinical manifestation observed in all affected 13 siblings from 5 independent families. Our data confirm the progressive nature of the disease also in milder LGMD phenotypes, ultimately resulting in loss of ambulation at a variable age. Our data define two major clinical POMT1 phenotypes, which should prompt genetic testing including the POMT1 gene: patients with a severe WWS manifestation predominantly present with profound neonatal muscular hypotonia and a severe and progressive hydrocephalus with involvement of brainstem and/or cerebellum. The presence of an occipital encephalocele in a WWS patient might point to POMT1 as causative gene within the different genes associated with WWS. The milder LGMD phenotypes constantly show markedly elevated creatine kinase values in combination with microcephaly and cognitive impairment.

Structural brain anomalies in patients with FOXG1 syndrome and in Foxg1+/- mice.

OBJECTIVE: FOXG1 syndrome is a rare neurodevelopmental disorder associated with heterozygous FOXG1 variants or chromosomal microaberrations in 14q12. The study aimed at assessing the scope of structural cerebral anomalies revealed by neuroimaging to delineate the genotype and neuroimaging phenotype associations. METHODS: We compiled 34 patients with a heterozygous (likely) pathogenic FOXG1 variant. Qualitative assessment of cerebral anomalies was performed by standardized re-analysis of all 34 MRI data sets. Statistical analysis of genetic, clinical and neuroimaging data were performed. We quantified clinical and neuroimaging phenotypes using severity scores. Telencephalic phenotypes of adult Foxg1+/- mice were examined using immunohistological stainings followed by quantitative evaluation of structural anomalies. RESULTS: Characteristic neuroimaging features included corpus callosum anomalies (82%), thickening of the fornix (74%), simplified gyral pattern (56%), enlargement of inner CSF spaces (44%), hypoplasia of basal ganglia (38%), and hypoplasia of frontal lobes (29%). We observed a marked, filiform thinning of the rostrum as recurrent highly typical pattern of corpus callosum anomaly in combination with distinct thickening of the fornix as a characteristic feature. Thickening of the fornices was not reported previously in FOXG1 syndrome. Simplified gyral pattern occurred significantly more frequently in patients with early truncating variants. Higher clinical severity scores were significantly associated with higher neuroimaging severity scores. Modeling of Foxg1 heterozygosity in mouse brain recapitulated the associated abnormal cerebral morphology phenotypes, including the striking enlargement of the fornix. INTERPRETATION: Combination of specific corpus callosum anomalies with simplified gyral pattern and hyperplasia of the fornices is highly characteristic for FOXG1 syndrome.

Association of homozygous LMNA mutation R471C with new phenotype: mandibuloacral dysplasia, progeria, and rigid spine muscular dystrophy.

We report on a 7-year-old girl with a phenotype combining mandibuloacral dysplasia (MAD), progeria, and rigid spine muscular dystrophy. Mild proximal weakness, contractures, and rigidity of the spine were the primary findings. Although present since birth, dysmorphic manifestations typical for MAD and progeroid features became more prominent with time, and the full clinical phenotype was recognizable at early school age. Her phenotype was caused by a homozygous mutation in LMNA (c.1411C > T, which predicts p.R471C) inherited from the heterozygous, consanguineous, unaffected parents. This mutation has only been reported in compound heterozygous state and was associated with a milder phenotype. Some LMNA mutations are known to cause MAD and overlapping phenotypes (MAD spectrum) in an autosomal recessive pattern. The p.R471C homozygous LMNA mutation causes a severe phenotype of the MAD spectrum. This case extends the clinical spectrum of MAD and further expands the phenotypic range of lamin A/C associated diseases.