NSD1 duplication in Silver-Russell syndrome (SRS): molecular karyotyping in patients with SRS features.

Silver-Russell syndrome (SRS) is a growth retardation syndrome characterized by intrauterine and postnatal growth retardation, relative macrocephaly and protruding forehead, body asymmetry and feeding difficulties. Nearly 50% of cases show a hypomethylation in 11p15.5, in 10% maternal uniparental disomy of chromosome 7 is present. A significant number of patients with SRS features also exhibit chromosomal aberrations. We analyzed 43 individuals referred for SRS genetic testing by molecular karyotyping. Pathogenic variants could be detected in five of them, including a NSD1 duplication in 5q35 and a 14q32 microdeletion. NSD1 deletions are detectable in overgrowth disorders (Sotos syndrome and Beckwith-Wiedemann syndrome), whereas NSD1 duplications are associated with growth retardation. The 14q32 deletion is typically associated with Temple syndrome (TS14), but the identification of a patient in our cohort reflects the clinical overlap between TS14 and SRS. As determination of molecular subtypes is the basis for a directed counseling and therapy, the identification of pathogenic variants in >10% of the total cohort of patients referred for SRS testing and in >16% of characteristic individuals with the characteristic SRS phenotype confirms the need to apply molecular karyotyping in this cohort.

Diagnostic algorithms in Charcot-Marie-Tooth neuropathies: experiences from a German genetic laboratory on the basis of 1206 index patients.

We present clinical features and genetic results of 1206 index patients and 124 affected relatives who were referred for genetic testing of Charcot-Marie-Tooth (CMT) neuropathy at the laboratory in Aachen between 2001 and 2012. Genetic detection rates were 56% in demyelinating CMT (71% of autosomal dominant (AD) CMT1/CMTX), and 17% in axonal CMT (24% of AD CMT2/CMTX). Three genetic defects (PMP22 duplication/deletion, GJB1/Cx32 or MPZ/P0 mutation) were responsible for 89.3% of demyelinating CMT index patients in whom a genetic diagnosis was achieved, and the diagnostic yield of the three main genetic defects in axonal CMT (GJB1/Cx32, MFN2, MPZ/P0 mutations) was 84.2%. De novo mutations were detected in 1.3% of PMP22 duplication, 25% of MPZ/P0, and none in GJB1/Cx32. Motor nerve conduction velocity was uniformly <38 m/s in median or ulnar nerves in PMP22 duplication, >40 m/s in MFN2, and more variable in GJB1/Cx32, MPZ/P0 mutations. Patients with CMT2A showed a broad clinical severity regardless of the type or position of the MFN2 mutation. Out of 75 patients, 8 patients (11%) with PMP22 deletions were categorized as CMT1 or CMT2. Diagnostic algorithms are still useful for cost-efficient mutation detection and for the interpretation of large-scale genetic data made available by next generation sequencing strategies.

Twenty-one years to the right diagnosis - clinical overlap of Simpson-Golabi-Behmel and Beckwith-Wiedemann syndrome.

Clinical overlap makes the diagnosis of overgrowth syndromes challenging. Clinical overlap exists between Simpson-Golabi-Behmel syndrome (SGBS) and Beckwith-Wiedemann syndrome (BWS) which share pre- and postnatal overgrowth, macroglossia, umbilical hernia, organomegaly, ear lobe creases, and occurrence of embryonal tumors as characteristic features. Based on the clinical history of a patient, who was diagnosed with BWS shortly after birth and reassessed and rediagnosed with SGBS at age 21 years, particular attention should be paid to developing facial dysmorphia. In addition, we delineate further clinical findings that may allow differentiation between both conditions.

Syndromic ciliopathies: From single gene to multi gene analysis by SNP arrays and next generation sequencing.

Joubert syndrome (JS) and related disorders (JSRD), Meckel syndrome (MKS) and Bardet-Biedl syndrome (BBS) are autosomal recessive ciliopathies with a broad clinical and genetic overlap. In our multiethnic cohort of 88 MKS, 61 JS/JSRD and 66 BBS families we performed genetic analyses and were able to determine mutation frequencies and detection rates for the most frequently mutated MKS genes. On the basis of determined mutation frequencies, a next generation gene panel for JS/JSRD and MKS was established. Furthermore 35 patients from 26 unrelated consanguineous families were investigated by SNP array-based homozygosity mapping and subsequent DNA sequencing of known candidate genes according to runs of homozygosity size in descending order. This led to the identification of the causative homozygous mutation in 62% of unrelated index cases. Based on our data we discuss various strategies for diagnostic mutation detection in the syndromic ciliopathies JS/JSRD, MKS and BBS.

Alcohol Consumption in Healthy OPRM1 G Allele Carriers and Its Association with Impulsive Behavior.

AIMS: A link between alcohol use disorders (AUD) and impulsivity is well established. As there is evidence for the heritability of AUD, the investigation of the underlying genetic disposition for both conditions is an important issue. An association between AUD and a coding single nucleotide polymorphism (SNP) (rs1799971 encoding an Asn40Asp amino acid substitution, A118G) within the µ-opioid receptor 1 gene (OPRM1) has been reported. Therefore we tested the association between the OPRM1 A118G polymorphism and drinking as well as impulsive behavior in social drinkers. METHODS: A total of 214 healthy male social drinkers were recruited. Each participant was genotyped for the OPRM1 A118G variant. Alcohol use was assessed with items of the Alcohol Use Disorders Identification Test (AUDIT). Impulsivity was assessed using the UPPS impulsive behavior scale. For statistical analyses, we considered correlations, t-tests and ordinal regression models using SPSS V21. RESULTS: In total, 49 out of 214 participants were carriers of the OPRM1 118G allele. On average the OPRM1 118G carriers showed a slightly higher propensity for alcohol drinking. Higher drinking frequency among the G allele carriers was linked with higher urgency and perseveration subscores of impulsivity. CONCLUSION: Our results suggest a genetically influenced higher propensity for alcohol drinking among social drinkers carrying the 118G allele of the OPRM1 gene. The positive correlation between urgency and a higher drinking frequency among the OPRM1 118G hint towards a functional meaning of the opioid system in the regulation of impulsivity.

[Non-invasive Genetic Prenatal Testing - A Serious Challenge for Society as a Whole]. / Nicht-invasive genetische Pränataldiagnostik - eine gesamtgesellschaftliche Herausforderung.

Non-invasive genetic prenatal tests nowadays allow a highly reliable identification of pregnancies with foetal aneuploidies. Due to the general availability of these tests for all pregnant women, non-invasive genetic prenatal testing raises many ethical questions whieh can only be answered by a debate focused on society as a whole.

[Genetics and epigenetics. Explanatory approaches for (gender-specific) mechanisms of disease development]. / Genetik und Epigenetik. Erklärungsansätze für (geschlechtsspezifische) Mechanismen der Krankheitsentstehung.

Whereas the central role of DNA as the carrier of genetic information has long been well known, the impact of epigenetic mechanisms as mediators between genes and environment is now becoming increasingly clear. Epigenetics helps explain the partially reversible interplay between gene function and environment and even permits observation of the transgenerational transmission of epigenetic modifications. Of special interest are gender-specific mechanisms of gene regulation which, among others, offer an explanation for gender differences in human diseases. Since the study of epigenetic mechanisms and their impact on the etiology of common diseases is in its infancy, it is too early to draw general conclusions from the current state of knowledge. Moreover, completely new strategies are needed to research these effects. In addition to molecular findings, definitions of specific phenotypes are required, including biographic data of affected individuals and their ancestors. Epigenetics needs to be viewed in the context of the theory of evolution, classical genetics, and environmental research. Its aim is not to substitute the knowledge in these disciplines, but rather to provide a key to link their findings, thereby opening up new possibilities in terms of interpretation and understanding of gender differences in medicine. If these epigenetic mechanisms are better understood, particularly in terms of specific diseases, it is conceivable that these disorders could be influenced and treated in a more targeted manner in the future.

Mapping of the gene for autosomal recessive polycystic kidney disease (ARPKD) to chromosome 6p21-cen.

Autosomal recessive polycystic kidney disease (ARPKD) is one of the major hereditary nephropathies in children predominantly presenting in early childhood. The clinical picture is variable but there is a fatal outcome in many cases. We have performed linkage analysis in 16 ARPKD families and localized the ARPKD gene to chromosomal region 6p21-cen with no evidence for genetic heterogeneity among different clinical phenotypes. Linkage was confirmed using six adjacent microsatellite markers and the highest lod score of 7.42 was obtained with D6S272 at theta = 0.00. Our findings should lead to more accurate forms of prenatal diagnosis than those currently available using ultrasound.

Identification of a candidate modifying gene for spinal muscular atrophy by comparative genomics.

Spinal muscular atrophy (SMA) is a common recessive disorder characterized by the loss of lower motor neurons in the spinal cord. The disease has been classified into three types based on age of onset and severity. SMA I-III all map to chromosome 5q13 (refs 2,3), and nearly all patients display deletions or gene conversions of the survival motor neuron (SMN1) gene. Some correlation has been established between SMN protein levels and disease course; nevertheless, the genetic basis for SMA phenotypic variability remains unclear, and it has been postulated that the loss of an additional modifying factor contributes to the severity of type I SMA. Using comparative genomics to screen for such a factor among evolutionarily conserved sequences between mouse and human, we have identified a novel transcript, H4F5, which lies closer to SMN1 than any previously identified gene in the region. A multi-copy microsatellite marker that is deleted in more than 90% of type I SMA chromosomes is embedded in an intron of this gene, indicating that H4F5 is also highly deleted in type I SMA chromosomes, and thus is a candidate phenotypic modifier for SMA.

Mutations in the gene encoding immunoglobulin mu-binding protein 2 cause spinal muscular atrophy with respiratory distress type 1.

Classic spinal muscular atrophy (SMA) is caused by mutations in the telomeric copy of SMN1. Its product is involved in various cellular processes, including cytoplasmic assembly of spliceosomal small nuclear ribonucleoproteins, pre-mRNA processing and activation of transcription. Spinal muscular atrophy with respiratory distress (SMARD) is clinically and genetically distinct from SMA. Here we demonstrate that SMARD type 1 (SMARD1) results from mutations in the gene encoding immunoglobulin micro-binding protein 2 (IGHMBP2; on chromosome 11q13.2-q13.4). In six SMARD1 families, we detected three recessive missense mutations (exons 5, 11 and 12), two nonsense mutations (exons 2 and 5), one frameshift deletion (exon 5) and one splice donor-site mutation (intron 13). Mutations in mouse Ighmbp2 (ref. 14) have been shown to be responsible for spinal muscular atrophy in the neuromuscular degeneration (nmd) mouse, whose phenotype resembles the SMARD1 phenotype. Like the SMN1 product, IGHMBP2 colocalizes with the RNA-processing machinery in both the cytoplasm and the nucleus. Our results show that IGHMBP2 is the second gene found to be defective in spinal muscular atrophy, and indicate that IGHMBP2 and SMN share common functions important for motor neuron maintenance and integrity in mammals.

Life with too much polyprenol: polyprenol reductase deficiency.

Congenital disorders of glycosylation (CDG) are caused by a dysfunction of glycosylation, an essential step in the manufacturing process of glycoproteins. This paper focuses on a 6-year-old patient with a new type of CDG-I caused by a defect of the steroid 5α reductase type 3 gene (SRD5A3). The clinical features were psychomotor retardation, pathological nystagmus, slight muscular hypotonia and microcephaly. SRD5A3 was recently identified encoding the polyprenol reductase, an enzyme catalyzing the final step of the biosynthesis of dolichol, which is required for the assembly of the glycans needed for N-glycosylation. Although an early homozygous stop-codon (c.57G>A [W19X]) with no functional protein was found in the patient, about 70% of transferrin (Tf) was correctly glycosylated. Quantification of dolichol and unreduced polyprenol in the patient's fibroblasts demonstrated a high polyprenol/dolichol ratio with normal amounts of dolichol, indicating that high polyprenol levels might compete with dolichol for the initiation of N-glycan assembly but without supporting normal glycosylation and that there must be an alternative pathway for dolichol biosynthesis.

Stress and coping in parents of children and adolescents with spinal muscular atrophy.

BACKGROUND: Chronic illness and disability is not only associated with higher rates of behavioural problems in children, but also parental stress which requires active coping. The aim of the study was to analyse stress and coping, as well as their mediating variables, in parents of children and adolescents with Spinal Muscular Atrophy (SMA). METHOD: 96 children and adolescents with SMA aged 6;0 to 18;11 years were compared to 59 age, sex and SES matched controls. RESULTS: Parental stress was measured with the QRS, coping with the F-COPES and social support with the F-SOZU questionnaires.Parental stress was significantly higher in the SMA families for the total score and all subscales of the QRS. Stress was higher in families with severely affected SMA types I and II. The greatest percentage of variance contributing to stress could be explained by lack of social support, degree of disability and behavioural problems in the child. Although social support was reduced, the actual coping abilities of the families did not differ. CONCLUSION: Families with children and adolescents with SMA show high degrees of stress and strain which are associated with the severity of the disease, reduced social support and child behaviour. Despite these stresses they manage and cope no differently from families with healthy children.

Long term peritoneal dialysis in an anuric preterm infant - a futile treatment?

The primarily anuric very low birth weight infant (VLBWI) is an ethical challenge for the attending doctor as well as for the parents. Long term peritoneal dialysis (PD) might provide an acceptable way in treating a primarily anuric VLBWI prior to kidney transplantation without endangering the child's neurologic development. We report a case of a VLBWI born at 30 weeks gestational age after anhydramnion for 5 weeks. Postnatally the neonate had persisting anuria and was successfully treated with peritonealdialysis for 31 months followed by hemodialysis for 12 months and eventually received a renal transplantion at the age of 43 months.

[Cystic kidney diseases]. / Zystennieren.

Cystic kidney diseases are clinically and genetically heterogeneous. The most important entities are autosomal-dominant and autosomal-recessive polycystic kidney diseases. The proteins encoded by the involved genes are referred to as cystoproteins, which are located predominantly in the primary cilia. Primary cilia play an important role in cyst formation. Inherited polycystic kidney diseases belong to the increasing number of reported ciliopathies, including several syndromic entities. An exact diagnosis is the basis for medical care and genetic counselling; thus, the diagnostic algorithm should include clinical, ultrasonographic and morphological features of the underlying kidney disease, knowledge about further features and family history. Molecular genetic testing may contribute important information towards a definite diagnosis.

[Non-directivity as a guiding category in human genetic counselling in a historical perspective]. / Nicht-Direktivität als Leitkategorie in der humangenetischen Beratung in zeithistorischer Betrachtung.

In this article we describe and analyse the issue of non-directivity in human genetic counselling in Germany between 1970 and 2010 based on printed sources and oral history interviews. The focus is on the extent to which the ethical aspects in genetic counselling were debated among human geneticists and to what extent aspects of non-directivity were discussed.As the results show, it was not only in retrospect that experts attributed great importance to the autonomy of those seeking advice and rejected "directive" advice, at least in public positions. They considered ethical justification to be central here.

Effects of a CACNA1C genotype on attention networks in healthy individuals.

BACKGROUND: Recent genetic studies found the A allele of the variant rs1006737 in the alpha 1C subunit of the L-type voltage-gated calcium channel (CACNA1C) gene to be over-represented in patients with psychosis, including schizophrenia, bipolar disorder and major depressive disorder. In these disorders, attention deficits are among the main cognitive symptoms and have been related to altered neural activity in cerebral attention networks. The particular effect of CACNA1C on neural function, such as attention networks, remains to be elucidated. METHOD: The current event-related functional magnetic resonance imaging (fMRI) study investigated the effect of the CACNA1C gene on brain activity in 80 subjects while performing a scanner-adapted version of the Attention Network Test (ANT). Three domains of attention were probed simultaneously: alerting, orienting and executive control of attention. RESULTS: Risk allele carriers showed impaired performance in alerting and orienting in addition to reduced neural activity in the right inferior parietal lobule [Brodmann area (BA) 40] during orienting and in the medial frontal gyrus (BA 8) during executive control of attention. These areas belong to networks that have been related to impaired orienting and executive control mechanisms in neuropsychiatric disorders. CONCLUSIONS: Our results suggest that CACNA1C plays a role in the development of specific attention deficits in psychiatric disorders by modulation of neural attention networks.

Brugada-like cardiac disease in myotonic dystrophy type 2: report of two unrelated patients.

BACKGROUND: Myotonic dystrophy type 2 (DM2) is an autosomal dominant multisystem disorder caused by CCTG repeat expansions within intron 1 of the ZNF9 gene on chromosome 3q. Cardiac conduction disturbances, supraventricular arrhythmias, and cardiomyopathy are described in DM2 but Brugada-like features have not yet been reported. Brugada syndrome (BS) is a genetically heterogeneous cardiac conduction disorder which is characterized by a significant ST-segment elevation upon ECG evaluations and bears an increased risk for sudden cardiac death. CASE REPORTS: We report two unrelated patients with genetically confirmed DM2 who developed clinical relevant cardiac arrhythmias with syncopal events from 35 (patient 1) and 47 years (patient 2). Brugada-like ECG findings were present in both patients. Family history was negative for BS, but the mothers of both index patients were also affected by DM2 and had different ventricular rhythm disturbances. SCN5A gene sequencing revealed an unknown genetic variant c.4140 C > A, p.N1380K, in patient 1, while no mutation was detected in patient 2. DISCUSSION: Our observations may suggest that Brugada-like cardiac arrhythmias can occur in DM2, as this seems also to be the case in DM1. The chance association of two independent inherited disorders has to be considered and cannot be excluded in one of our patients. However, on statistical grounds, this possibility cannot explain all observed cases of DM with Brugada-like cardiac disease.

Genetic variation in schizophrenia-risk-gene dysbindin 1 modulates brain activation in anterior cingulate cortex and right temporal gyrus during language production in healthy individuals.

Genetic variation in dysbindin 1 (DTNBP1) gene region tagged by SNP rs1018381 exhibits a linkage with cognitive deficits in patients with schizophrenia and healthy subjects. Language production deficits are core features of schizophrenia with more impairment in semantic than lexical verbal fluency tasks. We investigated the link between brain activation and DTNBP1 SNP rs1018381 during semantic verbal fluency task in a German healthy population. 46 healthy subjects genotyped for SNP rs1018381 status were divided in heterozygous risk-allele carriers (T/C) and homozygous non-carriers (C/C). Neural correlates of semantic verbal fluency were investigated with functional magnetic resonance imaging (fMRI). Stronger right hemispherical brain activation in anterior cingulate gyrus (BA 24), superior (BA 22, 38) and middle (BA 21) temporal gyrus was observed in the carriers compared to non-carriers. Brain activations occurred in the absence of task performance differences. No significant correlations were found between personality traits and brain activation differences. The results point to an influence of genetic variation in DTNBP1 gene region tagged by SNP rs1018381 on neural correlates of language production. Carriers may exhibit higher processing efforts to reach the same behavioural performance as non-carriers as reflected in activation of schizophrenia-related regions.

Genotype-phenotype studies in infantile spinal muscular atrophy (SMA) type I in Germany: implications for clinical trials and genetic counselling.

We reviewed the natural history and assessed the SMN2 copy number of 66 patients with infantile spinal muscular atrophy (SMA) type I born between 2000 and 2005 in Germany whose diagnosis was confirmed by a homozygous SMN1 deletion in the first 6 months of life. After excluding patients who had received valproic acid, the median/mean age at disease endpoint was 6.1/7.3 months (range 0.0-34.0). Four (6.1%) patients with one SMN2 copy had severe SMA type '0' with joint contractures and respiratory distress from birth. Median/mean age at onset (months) in 57 (86.3%) patients with two SMN2 copies was 1.2/1.3, and 3.5/3.4 in 5 (7.6%) patients with three SMN2 copies. Median/mean age at disease endpoint was 6.5/7.8 months (range 0.5-30) in patients with two SMN2 copies. All patients with three SMN2 copies were still alive at 10-55 months, two of them under permanent ventilation. Our data are relevant for prognostication and genetic counselling. The observed clinical variability, especially in the group with two SMN2 copies, might be important for clinical trials in SMA I where a possible control group could be defined as follows: age at onset within 4-5 months, age at genetic diagnosis <6 months, two SMN2 copies present, head control in less than 10%, no respiratory distress from birth, disease endpoint either age at death or age at permanent ventilation.