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DystrophicThus, the EB panel sequencing of genomic DNA, followed by a paternity test and analysis of microsatellite markers, as well as multiplex ligation-dependent probe amplification (MLPA) copy number analysis using patient and parental DNA, were performed.This approach revealed a paternally derived hemizygous deletion spanning from exon 3 to exon 118. Linear amplification-mediated PCR (LAM-PCR) determined the breaking points within intron 2 of the COL7A1 gene, comprising a 40kb segment within intron 1 of the adjacentThis report highlights the relevance of advanced molecular profiling to determine new/exceptional/unusual genotypes and the accurate mode of genetic transmission in DEB.

International audience; Histone Gene Cluster 1 Member E, HIST1H1E, encodes Histone H1.4, is one of a family of epigenetic regulator genes, acts as a linker histone protein, and is responsible for higher order chromatin structure. HIST1H1E syndrome (also known as Rahman syndrome, OMIM #617537) is a recently described intellectual disability (ID) syndrome. Since the initial description of five unrelated individuals with three different heterozygous protein-truncating variants (PTVs) in the HIST1H1E gene in 2017, we have recruited 30 patients, all with HIST1H1E PTVs that result in the same shift in frame and that cluster to a 94-base pair region in the HIST1H1E carboxy terminal domain. The identification of 30 patients with HIST1H1E variants has allowed the clarification of the HIST1H1E syndrome phenotype. Major findings include an ID and a recognizable facial appearance. ID was reported in all patients and is most frequently of moderate severity. The facial gestalt consists of a high frontal hairline and full lower cheeks in early childhood and, in later childhood and adulthood, affected individuals have a strikingly high frontal hairline, frontal bossing, and deep-set eyes. Other associated clinical features include hypothyroidism, abnormal dentition, behavioral issues, cryptorchidism, skeletal anomalies, and cardiac anomalies. Brain magnetic resonance imaging (MRI) is frequently abnormal with a slender corpus callosum a frequent finding.

The RASopathies are a group of clinically and genetically heterogeneous developmental disorders caused by dysregulation of the RAS/MAPK signalling pathway. Variants in several components and regulators of this pathway have been identified as the pathogenetic cause. In 2015, missense variants in A2ML1 were reported in three unrelated families with clinical diagnosis of Noonan syndrome (NS) and a zebrafish model was presented showing heart and craniofacial defects similar to those caused by a NS-associated Shp2 variant. However, a causal role of A2ML1 variants in NS has not been confirmed since. Herein, we report on 15 individuals who underwent screening of RASopathy-associated genes and were found to carry rare variants in A2ML1, including variants previously proposed to be causative for NS. In cases where parental DNA was available, the respective A2ML1 variant was found to be inherited from an unaffected parent. Seven index patients carrying an A2ML1 variant presented with an alternate disease-causing genetic aberration. These findings underscore that current evidence is insufficient to support a causal relation between variants in A2ML1 and NS, questioning the inclusion of A2ML1 screening in diagnostic RASopathy testing.

Contains fulltext : 169736.pdf (Publisher’s version ) (Closed access) Fibromuscular dysplasia (FMD) is a heterogeneous group of non-atherosclerotic and non-inflammatory arterial diseases that primarily involves the renal and cerebrovascular arteries. Grange syndrome is an autosomal-recessive condition characterized by severe and early-onset vascular disease similar to FMD and variable penetrance of brachydactyly, syndactyly, bone fragility, and learning disabilities. Exome-sequencing analysis of DNA from three affected siblings with Grange syndrome identified compound heterozygous nonsense variants in YY1AP1, and homozygous nonsense or frameshift YY1AP1 variants were subsequently identified in additional unrelated probands with Grange syndrome. YY1AP1 encodes yin yang 1 (YY1)-associated protein 1 and is an activator of the YY1 transcription factor. We determined that YY1AP1 localizes to the nucleus and is a component of the INO80 chromatin remodeling complex, which is responsible for transcriptional regulation, DNA repair, and replication. Molecular studies revealed that loss of YY1AP1 in vascular smooth muscle cells leads to cell cycle arrest with decreased proliferation and increased levels of the cell cycle regulator p21/WAF/CDKN1A and disrupts TGF-beta-driven differentiation of smooth muscle cells. Identification of YY1AP1 mutations as a cause of FMD indicates that this condition can result from underlying genetic variants that significantly alter the phenotype of vascular smooth muscle cells.

Ring chromosome 20 syndrome is a rare chromosomal disorder characterized by childhood-onset drug-resistant epilepsy, behavioral problems and variable cognitive impairment. While most cases occur sporadically, parent-to-child transmission of ring 20 mosaicism has only been reported in a few exceptional families. We identified a further family with mother-to-child transmission of ring 20 mosaicism. Detailed characterization of the ring chromosome showed a complete ring with preserved telomere repetitive sequences. SNP genotyping excluded mosaic uniparental disomy and indicated that the chromosome was transmitted without recombination from mother to child. These results corroborate the findings of a previous study and support the hypothesis that inherited mosaicism is due to transmission of an unstable chromosome either prone to ring opening or to ring re-formation.

Context: Autosomal dominant hypophosphatemic rickets (ADHR) is the only hereditary disorder of renal phosphate wasting in which patients may regain the ability to conserve phosphate. Low iron status plays a role in the pathophysiology of ADHR. Objective: This study reports of a girl with ADHR, iron deficiency, and a paternal history of hypophosphatemic rickets that resolved without treatment. The girl's biochemical phenotype resolved with iron supplementation. Subjects: A 26-month-old girl presented with typical features of hypophosphatemic rickets, short stature (79 cm; −2.82 SDS), and iron deficiency. Treatment with elemental phosphorus and calcitriol improved her biochemical profile and resolved the rickets. The girl's father had presented with rickets at age 11 months but never received medication. His final height was reduced (154.3 cm; −3.51 SDS), he had undergone corrective leg surgery and had an adult normal phosphate, fibroblast growth factor 23, and iron status. Father and daughter were found to have a heterozygous mutation in exon 3 of the FGF23 gene (c.536G>A, p.Arg179Gln), confirming ADHR. Intervention: Withdrawal of rickets medication was attempted off and on iron supplementation. Results: Withdrawal of rickets medication in the girl was unsuccessful in the presence of low-normal serum iron levels at age 5.6 years but was later successful in the presence of high-normal serum iron levels following high-dose iron supplementation. Conclusions: We report an association between iron supplementation and a complete loss of biochemical ADHR phenotype, allowing withdrawal of rickets medication. Experience from this case suggests that reduction and withdrawal of rickets medication should be attempted only after iron status has been optimized.

Zusammenfassung Für die Entstehung von uniparentalen Disomien (UPD) sind verschiedene Mechanismen bekannt, von denen insbesondere der häufigste, der „trisomy rescue“, mit Mosaiken aus einer trisomen Zelllinie und einer disomen 46,XN-Zelllinie mit UPD einhergehen kann. Daher wird diskutiert, ob ein Großteil der UPD schwache oder nichterkannte Mosaike sein könnten. Inwieweit eine trisome Zelllinie den Phänotyp beeinflusst, hängt wahrscheinlich vom Chromosom und v. a. vom prozentualen Anteil im jeweiligen Gewebe ab. Möglicherweise haben die trisomen Zellen mancher UPD-Mosaike sogar einen Selektionsnachteil, sodass sie zumindest postnatal in der Routineanalytik aus Lymphozyten nicht darstellbar sind. Bei Beteiligung eines Chromosoms, für das „Imprinting“-Phänomene bekannt sind, muss die entsprechende Erkrankung berücksichtigt werden. Während die postnatale molekulare Abklärung einer UPD bei Vorliegen einer entsprechenden klinischen Symptomatik und/oder chromosomaler bzw. molekularer Vorbefunde indiziert ist, sind im Rahmen der pränatalen Testung auf UPD und Imprinting-Erkrankungen die Konsequenzen eines positiven Befunds vor der Diagnostik im Rahmen einer genetischen Beratung mit den Eltern zu diskutieren. Die Bedeutung von Mosaiken für die UPD-Diagnostik muss vor dem Hintergrund des beteiligten Chromosoms bzw. der assoziierten Erkrankung, des zugrunde liegenden Entstehungsmechanismus und der verwendeten Methode bewertet werden.

Fragile X syndrome characterized by intellectual disability (ID), facial dysmorphism, and postpubertal macroorchidism is the most common monogenic cause of ID. It is typically induced by an expansion of a CGG repeat in the fragile X mental retardation 1 (FMR1) gene on Xq27 to more than 200 repeats. Only rarely patients have atypical mutations in the FMR1 gene such as point mutations, deletions, or unmethylated/partially methylated full mutations. Most of these patients show a minor phenotype or even appear clinically healthy. Here, we report the dysmorphism and clinical features of a 17-year-old boy with a partially methylated full mutation of approximately 250 repeats. Diagnosis was made subsequently to the evaluation of a FMR1 premutation as the cause for maternal premature ovarian failure. Dysmorphic evaluation revealed no strikingly long face, no prominent forehead/frontal bossing, no prominent mandible, no macroorchidism, and a head circumference in the lower normal range. Acquisition of a driving license for mopeds and unaccompanied rides by public transport in his home province indicate rather mild ID (IQ = 58). Conclusion: This adolescent demonstrates that apart from only minor ID, patients with a partially methylated FMR1 full mutation present less to absent pathognomonic facial dysmorphism, thus emphasizing the impact of family history for a straightforward clinical diagnosis.

Epilepsy is a common finding in patients with chromosomal macro- and micro-rearrangements but only few aberrations show a constant pattern of seizures. DNA array-based studies have reported causative copy number variations (CNVs) in 5-30% of patients with epilepsy with or without co-morbidities. The interpretation of many of the detected CNVs remains challenging. In order to identify CNVs carrying epilepsy-related genes we investigated 43 children with various patterns of epileptic seizures, intellectual disability (ID), and minor dysmorphism, using the Illumina® Infinium Human1M-DuoV1 array. In three patients we found likely causative de novo CNVs, i.e. deletions in 1q41q42.12 (3.4 Mb) and 19p13.2 (834 kb), and a mosaic two-segment duplication in 17p13.2 (218 kb) and 17p13.1 (422 kb). In six additional patients there were aberrations (a deletion in one and duplications in five patients) with uncertain clinical consequences. In total, the finding of causative chromosomal micro-rearrangements in 3 out of 43 patients (7%) and potentially causative CNVs in 6 additional patients (14%) with epilepsy and ID but without major malformations confirms the power of DNA arrays for the detection of new disease-related genetic regions.

De novo combined duplications/inversions are very rare chromosomal rearrangements. For chromosome 7 just some dozen cases of duplications of various parts of the long arm have been published. We report on a 12-year-old boy with muscular hypotonia, global developmental delay, short stature, and various facial dysmorphism including frontal bossing, temporal narrowing, slightly down-slanting palpebral fissures, a broad nasal root, a long philtrum, a thin and tented upper lip, a drooping lower lip, micrognathia, prominent ears, a short neck, and a low posterior hairline. Karyotype analysis and molecular investigations revealed a complex de novo chromosomal rearrangement on 7q. FISH analysis with locus specific YACs and BACs and SNP array with the Illumina(®) HumanOmni1-Quad v1.0 BeadChip disclosed a direct duplication in the long arm of chromosome 7 (q22.1→q32.2) and an inversion located at the breakpoint between the two copies of the duplication (q31.31→q31.33). In addition, breakpoint characterization at the molecular level revealed a 386 bp insertion carrying two Alu elements of chromosome 19p13.2 between the two copies of the duplication. By a comparison of the SNP haplotypes of the derivative chromosome of the patient and both parents a two-step formation during spermatogenesis was suggested as the most likely mechanism of formation.

Idiopathic infantile hypercalcaemia (IIH) is an autosomal recessively inherited disease, presented in the first year of life with hypercalcaemia, precipitated by normal amounts of vitamin D supplementation. Recently loss-of-function mutations in the CYP24A1 gene, which encodes the vitamin D-metabolizing enzyme 24-hydroxylase, have been found in these patients. We describe a young man homozygous for a novel missense mutation (c.628T>C) of the CYP24A1 gene. He had suffered from severe hypercalcaemia in early childhood. At age 29 he presented with medullary nephrocalcinosis, chronic kidney disease (CKD) stage 2, microalbuminuria, mild hypertension and nephrogenic diabetes insipidus. He had mild hypercalcaemia and moderate hypercalciuria. As a novel finding, fibroblast growth factor 23 (FGF23) was elevated.

Most balanced chromosomal aberrations are not associated with a clinical phenotype, however, in some patients they may disrupt gene structure. With the development of various next-generation sequencing techniques, fast and specific analyses of the breakpoint regions of chromosomal rearrangements are possible. Here, we report on a 19-year-old woman with a de novo balanced translocation t(2;8)(p13.2;q22.1) and a severe clinical phenotype including intellectual disability, epilepsy, behavioral features resembling autism, and minor dysmorphic features. By next-generation sequencing, we defined the breakpoints and found disruption of the exocyst complex component 6B (EXOC6B) gene in intron 1 on chromosome 2p13.2 involving two Alu elements with a homology of 81%. No gene was found at the respective breakpoint on chromosome 8. Expression analysis of the EXOC6B in blood lymphocytes and buccal smear revealed reduced expression in the patient in comparison with the control. Our findings in combination with one recently published case and one other patient listed in DECIPHER v5.1 indicate EXOC6B as a gene relevant for intellectual development and electrophysiological stability.

Chromosomal abnormalities are implicated in a substantial number of human developmental syndromes, but for many such disorders little is known about the causative genes. The recently described 1q41q42 microdeletion syndrome is characterized by characteristic dysmorphic features, intellectual disability and brain morphological abnormalities, but the precise genetic basis for these abnormalities remains unknown. Here, our detailed analysis of the genetic abnormalities of 1q41q42 microdeletion cases identified TP53BP2, which encodes apoptosis-stimulating protein of p53 2 (ASPP2), as a candidate gene for brain abnormalities. Consistent with this, Trp53bp2-deficient mice show dilation of lateral ventricles resembling the phenotype of 1q41q42 microdeletion patients. Trp53bp2 deficiency causes 100% neonatal lethality in the C57BL/6 background associated with a high incidence of neural tube defects and a range of developmental abnormalities such as congenital heart defects, coloboma, microphthalmia, urogenital and craniofacial abnormalities. Interestingly, abnormalities show a high degree of overlap with 1q41q42 microdeletion-associated abnormalities. These findings identify TP53BP2 as a strong candidate causative gene for central nervous system (CNS) defects in 1q41q42 microdeletion syndrome, and open new avenues for investigation of the mechanisms underlying CNS abnormalities.Cell Death and Differentiation advance online publication, 22 July 2016; doi:10.1038/cdd.2016.76.

Multicentric osteolysis, nodulosis and arthropathy (MONA) spectrum disorder is a rare inherited progressive skeletal disorder caused by mutations in the matrix metalloproteinase 2 (MMP2) gene. Treatment options are limited. Herein we present successful bisphosphonate therapy in three affected patients. Patients were treated with bisphosphonates (either pamidronate or zoledronate) for different time periods. The following outcome variables were assessed: skeletal pain, range of motion, bone densitometry, internal medical problems as well as neurocognitive function. Skeletal pain was dramatically reduced in all patients soon after initiation of therapy and bone mineral density increased. Range of motion did not significantly improve. One patient is still able to walk with aids at the age of 14 years. Neurocognitive development was normal in all patients. Bisphosphonate therapy was effective especially in controlling skeletal pain in MONA spectrum disorder. Early initiation of treatment seems to be particularly important in order to achieve the best possible outcome.

Exact breakpoint determination by DNA-array has dramatically improved the analysis of genotype-phenotype correlations in chromosome aberrations. It allows a more exact definition of the most relevant genes and particularly their isolated or combined impact on the phenotype in an unbalanced state. Here, we report on a 21-year-old female with severe growth retardation, severe intellectual disability, hypoplasia of the corpus callosum, unilateral sacral hypoplasia, tethered cord, various minor facial dysmorphisms, and a telomeric deletion of about 4.4 Mb in 7q36.2->qter combined with a telomeric duplication of about 8 Mb in 17pter->p13.1. Fine mapping was achieved with the Illumina® Infinium HumanOmni1-Quad v1.0 BeadChip. Most of the major clinical features correspond to the well-known effects of haploinsufficiency of the MNX1 and SHH genes. In addition, review of the literature suggests an association of the 17p duplication with specific facial dysmorphic features and skeletal anomalies, but also an aggravating effect of the duplication-deletion for severe growth retardation as well as sacral and corpus callosum hypoplasia by one or more genes located on the proximal half of the segmental 17p duplication could be elaborated by comparison with other patients from the literature carrying either the deletion or the duplication found in our patient.

Summary Progressive myoclonic epilepsy (PME) is a heterogeneous group of epilepsies characterized by myoclonus, seizures and progressive neurological symptoms. The index patient was a 6-year old boy showing early-onset therapy resistant PME and severe developmental delay. Genome-wide linkage analysis identified several candidate regions. The potassium channel tetramerization domain containing 7 gene (KCTD7) in the 7q11.21 linkage region emerged as a suitable candidate. Sequence analysis revealed a novel homozygous missense mutation (p.R94W) in a highly conserved segment of exon 2. This is the second family with PME caused by KCTD7 mutations, hence KCTD7 mutations might be a recurrent cause of PME.

De novo cytogenetically balanced reciprocal non-Robertsonian translocations are rare findings in clinical cytogenetics and might be associated with an abnormal phenotype. Knowledge of the parental origin and mechanisms of formation is still limited. By microdissection of the derivative chromosomes and their normal homologs from metaphases followed by microsatellite-mediated marker analysis we identified 7 cases of paternal and 3 cases of maternal origin in a cohort of 10 patients with de novo cytogenetically balanced reciprocal non-Robertsonian translocations. Neither in the maternal nor in the paternal group of our study parental age seems to be increased. Together with the data from the literature our results confirm that the majority of de novo cytogenetically balanced reciprocal translocations are of paternal origin, but the preponderance does not appear to be as distinct as previously thought and the paternal age does not seem to be necessarily a major contributing factor.

Constitutional insertional translocations are rare findings in clinical cytogenetics. Here, we report on the unbalanced segregation of a balanced paternal insertional translocation ins(7;6)(p15;q16.1q21) to three children. Investigations by conventional karyotyping, FISH with locus-specific probes, microsatellite marker analysis, and SNP-array based copy number analysis revealed a direct orientation of the inserted segment, a size of 11.3 Mb, and breakpoints between rs4370337 and rs12660854 and rs12110990 and rs4946730 on 6q16.1 and 6q21, respectively, as well as within BAC clone RP11–182J2 on 7p15. A 17-year-old daughter inherited the der(6) chromosome and was affected by severe mental retardation, obesity, and minor anomalies. Two further children inherited the der(7) chromosome. A daughter shows an almost unremarkable phenotype and only minor features in neuropsychological testing at 19 years of age. Her 14-year-old half-brother demonstrates a mild delay in cognitive development most likely jointly caused by the chromosomal rearrangement and asphyxia during delivery. The patient with the deletion confirms the previously reported phenotype of severe mental retardation and obesity in patients with del(6)(q16.2), while both patients with partial trisomy for the same segment of chromosome 6 are further examples for a generally less severe phenotype associated with duplications than with deletions, and even for the recent insight that chromosomal aneusomies of several megabases may go without major clinical consequences. © 2010 Wiley-Liss, Inc.

Background: Williams-Beuren syndrome (WBS) is a developmental disorder with multisystemic manifestations mainly characterized by vascular stenoses, distinctive craniofacial features, mental retardation with a characteristic neurocognitive profile and some endocrine and connective tissue abnormalities, caused by a recurrent deletion of 1.55 Mb including 26-28 genes at chromosomal region 7q11.23. The analysis of clinical-molecular correlations in a few reported atypical patients has been useful to propose several deleted genes as main contributors to specific aspects of the WBS phenotype. Patients and methods: We have studied two additional families with partial phenotypes and atypical 7q11.23 deletions. Deletions were precisely defined at the nucleotide level and expression levels of some affected and flanking genes were assessed in lymphoblastoid cell lines. Results: Affected individuals presented variable cardiovascular and connective tissue manifestations, subtle craniofacial features, normal visuospatial construction abilities with low average IQ and no endocrine abnormalities. The deletion in family NW1 encompassed 817 kb with 11 genes (CLDN3-GTF2IRD1), and 610 kb with 14 genes (VPS37D-RFC2) in family NW2. All deleted genes in typical and atypical deletions revealed low expression levels in lymphoblastoid cell lines, except for GTF2IRD1. CLIP2 was also underexpressed in all patients despite being outside the deletion in NW2, while no other flanking non-deleted gene showed significantly different expression compared to controls. Conclusions: Along with previously reported cases, clinical-molecular correlations in these two families further corroborate that functional hemizygosity for the GTF2I +/- GTF2IRD1 genes is the main cause of the neurocognitive profile and some aspects of the gestalt phenotype of WBS.

Partial duplication 3q is a well defined clinical entity characterized by growth retardation, cryptorchism, microcephaly, and characteristic dysmorphisms. Most patients present with large duplications or are associated with a second chromosomal imbalance, which makes the definition of the phenotype difficult. Here, we report on a 4-year and 8-month-old girl with pre- and postnatal measurements in the high normal range, developmental delay, minor dysmorphic features, and a de novo unbalanced 3/4 translocation with trisomy 3q27 --> qter and monosomy of the subtelomeric region of 4p. Conventional karyotyping, FISH with probes from the Wolf-Hirschhorn syndrome critical region and chromosome 4p locus-specific probes, microsatellite marker-based haplotyping, and SNP microarray copy number analysis revealed a terminal 4p deletion of less than 500 kb with a breakpoint distal to the Wolf-Hirschhorn syndrome critical region, a chromosome 3q duplication of around 15.3 Mb, with origin of the rearrangement in paternal meiosis. Thus, our case clearly characterizes the phenotype of pure partial duplication 3q more exactly, and moreover, indicates that small chromosome rearrangements might lead to growth in the upper normal range or even cause overgrowth.

Chest wall deformities such as pectus excavatum, pectus carinatum, and cleft sternum can be isolated malformations or dysmorphic features of genetic associations, monogenic disorders, and various numeric and structural chromosomal aberrations. In contrast to the most important syndromes such as Marfan syndrome or Noonan syndrome that can be associated with a chest wall deformity and for which the causative genes are known, etiology of isolated chest wall deformities is still a matter of research. Therefore, an interdisciplinary approach, particularly in patients with additional symptoms is strongly recommended to choose the best therapeutic approach for each patient and its family.

Diploid/triploid mosaicism is a rare chromosome aberration characterized by growth and mental retardation, muscular hypotonia, clinodactyly, syndactyly of fingers and toes, asymmetry of the body and the face, truncal obesity, and pigmentary anomalies of the skin. Many patients initially present with severe growth retardation and develop truncal obesity later in life. Variable phenotype expression during development and restriction of triploid cells to certain tissues explain why the diagnosis of diploid/triploid mosaicism is often delayed. Here, we report on a moderately retarded 14-year-old girl with diploid/triploid mosaicism due to inclusion of the second polar body, whose changing phenotype overlaps considerably with different genetic disorders associated with aberrant genomic imprinting. The observation that triploid cells, which in our patient show remarkably variable distribution in different tissues, may also be present in easily accessible tissues such as urinary sediment or buccal smear may contribute to an earlier diagnosis of this rare syndrome.

Objective: To review all cases with segmental and/or complex uniparental disomy (UPD) and to discuss the impact of these cases on Medical Genetics. Design: Searching for published reports in Pubmed and in the abstract books of the annual meetings of the American Society of Human Genetics and the European Society of Human Genetics up to March 2008. Results: In total, 26 cases with segmental UPD and a normal karyotype, 38 cases with UPD of a whole chromosome and a simple reciprocal or non-homologous Robertsonisn translocation, four cases each with two isochromosomes and UPD of the short arm isochromosme and opposite UPD of the long arm isochromosome, three cases with UPD and an isochromosome of the short arm and the long arm of a metacentric or a submetacentric chromosome, one case with maternal UPD and an isochromosome 8 associated with a homozygous deletion (8)(p23.3pter), 42 cases with UPD and an isochromosome of the long arm of an acrocentric chromosome, 33 cases with UPD and a supernumerary marker or ring chromosome, 17 cases with UPD of a whole or parts of a chromosome and a complex karyotype, 13 cases with most likely mosaicism for genome-wide paternal UPD, and 3 cases with most likely mosaicism for genome-wide maternal UPD were found. Conclusion: This update shows that particularly the number of reported cases with segmental UPD or UPD associated with a marker chromosome clearly increased within the last years, and that the investigation of both parents in cases with homozygosity of an autosomal recessively inherited mutation in some cases might help improving genetic counselling coming to a reduced recurrence risk in the case of UPD. Moreover, cases with segmental or complex UPD show that meiosis and early postzygotic mitoses seem to be more complex events than previously thought. For the formation of all kinds of segmental or complex UPD or genome-wide UPD mosaicism always a fortunate cooccurrence of meiotic or mitotic recombination, abnormal segregation, and subsequent correction are necessary. No case of recurrence has been reported until now. Therefore, in subsequent pregnancies invasive prenatal diagnosis is not necessarily indicated.

Background Beckwith–Wiedemann syndrome (BWS) is an early-onset overgrowth disorder with a high risk for embryonal tumors. It is mainly caused by dysregulation of imprinted genes on chromosome 11p15.5; however, the driving forces in the development of tumors are not fully understood. Procedure We report on a female patient presenting with macrosomia, macroglossia, organomegaly and extensive bilateral nephroblastomatosis. Adjuvant chemotherapy was initiated; however, the patient developed hepatoblastoma and Wilms tumor at 5 and 12 months of age, respectively. Subsequent radiofrequency ablation of the liver tumor and partial nephrectomy followed by consolidation therapy achieved complete remission. Results Molecular genetic analysis revealed a maternally derived large deletion of the complete H19-differentially methylated region (H19-DMR; imprinting control region-1 [ICR1]), the whole H19 gene itself as well as large parts of the distal enhancer region within the imprinting cluster-1 (IC1). Extended analysis showed highly elevated insulin-like growth factor 2 (IGF2) expression, possibly explaining at least in part the distinct BWS features and tumor manifestations. Conclusions This study of a large maternal deletion encompassing the H19 gene and complete ICR1 is the first to demonstrate transcriptional consequences on IGF2 in addition to methylation effects resulting in severe overgrowth and occurrence of multiple tumors in a BWS patient. Studying this deletion helps to clarify the complex molecular processes involved in BWS and provides further insight into tumorigenesis.

Growth retardation has been reported in most cases of maternal uniparental disomy (UPD) 7 and 14, but has never been evaluated in a systematic approach. In this study, an analysis is presented of the auxological data from the literature at birth and on the occasion of the last evaluation of 34 cases with maternal UPD 7 (21 heterodisomy, 13 isodisomy) and 29 cases with maternal UPD 14 (22 heterodisomy, 7 isodisomy). For maternal UPD 7, statistical analysis revealed that length and weight at birth as well as on the occasion of the last evaluation were strongly below average (-2.94 SD and -2.62 SD, and -3.39 SD and -3.11 SD, respectively), whereas at both evaluations occipitofrontal head circumference (OFC) was only slightly below the average (-1.00 SD and -0.85 SD). For maternal UPD 14 at birth, growth retardation is rather concordant for length, weight, and OFC (-2.78 SD, -2.84 SD, and -1.69 SD). Later in life body mass index (BMI) is above average (1.06 SD) and continuously increasing before and after puberty (-0.58 SD and 2.07 SD).Growth retardation and relative macrocephaly are of prenatal onset and still present in adults with maternal UPD 7. For patients with maternal UPD 14, growth curves for height, BMI and OFC differ strongly. Genomic imprinting might be a major causative factor, but it seems to function differently for maternal UPD 7 and maternal UPD 14.

Submitted by Vitor Silverio Rodrigues (vitorsrodrigues@reitoria.unesp.br) on 2014-05-27T11:22:37Z No. of bitstreams: 0Bitstream added on 2014-05-27T14:33:38Z : No. of bitstreams: 1 2-s2.0-35349019691.pdf: 4144234 bytes, checksum: 9b86846640bd2e66375c65e289357bd0 (MD5) Made available in DSpace on 2014-05-27T11:22:37Z (GMT). No. of bitstreams: 0 Previous issue date: 2007-10-24 Aicardi-Goutières syndrome (AGS) is a genetic encephalopathy whose clinical features mimic those of acquired in utero viral infection. AGS exhibits locus heterogeneity, with mutations identified in genes encoding the 3′→5′ exonuclease TREX1 and the three subunits of the RNASEH2 endonuclease complex. To define the molecular spectrum of AGS, we performed mutation screening in patients, from 127 pedigrees, with a clinical diagnosis of the disease. Biallelic mutations in TREX1, RNASEH2A, RNASEH2B, and RNASEH2C were observed in 31, 3, 47, and 18 families, respectively. In five families, we identified an RNASEH2A or RNASEH2B mutation on one allele only. In one child, the disease occurred because of a de novo heterozygous TREX1 mutation. In 22 families, no mutations were found. Null mutations were common in TREX1, although a specific missense mutation was observed frequently in patients from northern Europe. Almost all mutations in RNASEH2A, RNASEH2B, and RNASEH2C were missense. We identified an RNASEH2C founder mutation in 13 Pakistani families. We also collected clinical data from 123 mutation-positive patients. Two clinical presentations could be delineated: an early-onset neonatal form, highly reminiscent of congenital infection seen particularly with TREX1 mutations, and a later-onset presentation, sometimes occurring after several months of normal development and occasionally associated with remarkably preserved neurological function, most frequently due to RNASEH2B mutations. Mortality was correlated with genotype; 34.3% of patients with TREX1, RNASEH2A, and RNASEH2C mutations versus 8.0% RNASEH2B mutation-positive patients were known to have died (P = .001). Our analysis defines the phenotypic spectrum of AGS and suggests a coherent mutation-screening strategy in this heterogeneous disorder. Additionally, our data indicate that at least one further AGS-causing gene remains to be identified. © 2007 by The American Society of Human Genetics. All rights reserved. Leeds Institute of Molecular Medicine, Leeds DNA Laboratory Department of Clinical Genetics St. James's University Hospital, Leeds Cancer Research UK Mutation Detection Facility, Leeds Department of Paediatric Neurology Leeds General Infirmary, Leeds Department of Paediatric Neurology Erasme Hospital, Brussels Children's Hospital Queen Fabiola, Brussels Service de Neuropédiatrie Hôpital Trousseau Department of Paediatric Neurology Hôpital Trousseau Pediatric Neurology Department Hôpital Bicêtre Institut de Myologie Groupe Hospitalier Pitié-Salpêtrière Service de Virologie Hôpital Cochin-St. Vincent de Paul, Paris Department of Clinical Biochemistry Hospital Sant Joan de Déu-Ciberer, Barcelona Department of Barcelona Pediatric Neurology Hospital Sant Joan de Déu-Ciberer, Barcelona Department of Paediatrics St. Luke's Hospital, Guardamangia Department of Molecular and Human Genetics Baylor College of Medicine, Houston Serive de Neurologie Centre Hospitalier, Pau Department of Paediatrics Children's Hospital, Sheffield Developmental and Metabolic Neurology Branch National Institute of Neurological Disorders and Stroke National Institutes of Health, Bethesda Department of Human Genetics Rheinisch-Westfälische Technische Hochschule Aachen University, Aachen Unit of Molecular Medicine Bambino Gesù Children's Research Hospital, Rome Istituto di Ricerca e Cura a Carattere Scientifico (IRCCS) Casa Sollievo Della Sofferenza Mendel Institute, Rome Muscular and Neurodegenerative Disease Unit G. Gaslini Institute, Genova Department of Clinical Genetics Churchill Hospital, Oxford Division of Clinical Chemistry and Biochemistry University Children's Hospital, Zurich Clinical Genetics Unit Birmingham Women's Hospital, Birmingham Department of Paediatrics Sandwell and West Birmingham NHS Trust, Birmingham Neurology Department Birmingham Children's Hospital, Birmingham Department of Human Genetics Radboud University, Nijmegen Department of Pediatric Neurology Radboud University, Nijmegen Department of Paediatric Neurology Royal Children's Hospital, Brisbane, QLD Genetic Health Queensland Royal Children's Hospital, Brisbane, QLD Serviço de Aconselhamento Genético Universidade Estadual de São Paulo, Botucatu Academic Unit of Medical Genetics St. Mary's Hospital, Manchester Kinderkrankenhaus Auf der Bult, Hannover Department of Paediatrics Bradford National Health Service (NHS) Trust, Bradford Developmental Neurology Department Fondazione Istituto Neurologico C. Besta, Milan Grampian Clinical Genetics Centre, Aberdeen Department of Neonatology University Hospital, Ghent Department of Pediatrics University Hospital, Ghent Department of Clinical Genetics Maastricht University Hospital, Maastricht Department of Neurology Maastricht University Hospital, Maastricht Department of Paediatrics and Imaging Sciences Imperial College Great Ormond Street Hospital, London St. Mary's NHS Trust Great Ormond Street Hospital, London Department of Ophthalmology Great Ormond Street Hospital, London North East Thames Regional Genetics Service Great Ormond Street Hospital, London Evelina Children's Hospital Guy's and St. Thomas' NHS Trust, London Department of Paediatrics Université Laval Medical School, Québec Clinical Genetics Unit Hospital de Cruces, Baracaldo Service de Génétique Médicale Centre Hospitalier Universitaire Pellegrin Enfants, Bordeaux Unité de Neurologie de l'Enfant et de l'Adolescent Centre Hospitalier Universitaire Pellegrin Enfants, Bordeaux National Centre for Medical Genetics Our Lady's Hospital, Dublin Department of Paediatric Neurology Children's University Hospital, Dublin Department of Medical Genetics Rikshospitalet-Radiumhospitalet, Oslo Department of Paediatrics Rikshospitalet-Radiumhospitalet, Oslo Rikshospitalet-Radiumhospitalet, Oslo Department of Pediatrics Academic Medical Center, Amsterdam Department of Child Neurology Vrije Universiteit Medical Center, Amsterdam Medical Research Council Human Genetics Unit Western General Hospital, Edinburgh Department of Clinical Genetics Leiden University Medical Center, Leiden Division of Pediatric Neurology Oregon Health and Science University, Portland, OR Pediatric Neurology Klinikum Aschaffenburg, Aschaffenburg Department of Neurology Royal Children's Hospital, Parkville, Vic. Division of Clinical Genetics Department for Medical Genetics Medical University Innsbruck, Innsbruck Department of Pediatrics Division of Pediatric Neurology and Inborn Errors of Metabolism Children's Hospital Innsbruck, Innsbruck Klinik für Kinder und Jugendliche, Konstanz Paediatric Neurology University Hospitals of Gasthuisberg, Leuven Department of Child Neurology and Psychiatry IRCCS Casimiro Mondino Institute of Neurology, Pavia Department of Neurogenetics School of Medicine of Ribeirao Preto, Ribeirao Preto Greenwood Genetic Center, Greenwood, SC Raphael Recanati Genetic Institute Rabin Medical Center, Petach-Tikva Department of Paediatrics Crosshouse Hospital, Ayr Fraser of Allander Neurosciences Unit Royal Hospital for Sick Children, Glasgow Duncan Guthrie Institute of Medical Genetics Royal Hospital for Sick Children, Glasgow Division of Medical Genetics Montreal Children's Hospital, Montreal Department of Paediatric Neurology University Hospitals of Leicester NHS Trust, Leicester University Hospital of Aarhus, Aarhus Division of Pediatric Dermatology British Columbia's Children's Hospital, Vancouver, BC Institut de Pathologie et de Génétique, Gosselies Pediatric Neurology Department Guide Chauliac Hospital, Montpellier Servicio de Pediatría Hospital Universitario Doctor Peset, Valencia Genetic Institute Ha'Emek Medical Center, Afula Rappaport Faculty of Medicine Technion, Haifa Neuropediatrics Unit Complejo Hospitalario de Jean, Jean Department of Paediatrics Manor Hospital, Walsall Division of Neuropediatrics University Hospital, Freiburg Genetic Health Services Victoria Royal Children's Hospital, Vic. Service de Génétique Hôpital Debrousse, Lyon Lancashire Teaching Hospitals Trust, Preston Neonatal Intensive Care Unit Arcispedale Santa Maria Nuova, Reggio Emilia Center for Medical Genetics, Antwerp Department of Neurology Children's National Medical Center, Washington, DC Department of Neuropediatrics Humboldt University, Berlin Leeds Institute of Molecular Medicine St. James's University Hospital Wellcome Trust Brenner Building, Leeds LS9 7TF Serviço de Aconselhamento Genético Universidade Estadual de São Paulo, Botucatu

Okihiro/Duane-radial ray syndrome (DRRS) is an autosomal dominant condition characterized by radial ray defects and Duane anomaly (a form of strabismus). Other abnormalities reported in this condition are anal, renal, cardiac, ear, and foot malformations, and hearing loss. The disease is the result of a mutation in the SALL4 gene, a human gene related to the developmental regulator spalt (sal) of Drosophila melanogaster. SALL4 mutations may also cause acro-renal-ocular syndrome (AROS), which differs from DRRS by the presence of structural eye anomalies, and phenotypes similar to thalidomide embryopathy and Holt-Oram syndrome (HOS). The SALL4 gene product is a zinc finger protein that is thought to act as a transcription factor. It contains three highly conserved C2H2 double zinc finger domains, which are evenly distributed. A single C2H2 motif is attached to the second domain, and at the amino terminus SALL4 contains a C2HC motif. Seventeen of the 22 SALL4 mutations known to date (five of which are presented here for the first time) are located in exon 2, and five are located in exon 3. These are nonsense mutations, short duplications, and short deletions. All of the mutations lead to preterminal stop codons and are thought to cause the phenotype via haploinsufficiency. This assumption is supported by the detection of six larger deletions involving the whole gene or single exons. This article summarizes the current knowledge about SALL4 defects and associated syndromes, and describes the clinical distinctions with similar phenotypes caused by other gene defects. Hum Mutat 26(3), 176–183, 2005. © 2005 Wiley-Liss, Inc.

We report on an adult male with Klinefelter phenotype and an isodicentric Y chromosome (47,XX,+idic(Y)(q12)), a combination which has to the best of our knowledge not been reported before. The patient was hospitalized in forensic psychiatry because of repeated delinquency, aggressive, aberrant and inappropriate behavior, and borderline intelligence. Molecular cytogenetic studies (FISH) showed that the SRY gene was present on both ends of the idicY, while there was only one signal for the Yq subtelomere probe. Molecular investigations by multiplex PCR, using STS markers covering the short and long arm of the Y chromosome did not indicate a deletion of Y chromosomal material. Molecular investigations of STR markers located on Xp22.3 and Xq28 indicated paternal origin of the additional X chromosome and an error in paternal meiosis I. Results of FISH analysis and molecular investigations are compatible with a phenotype as described for individuals with a 48,XXYY karyotype and support the findings that isodicentric Y chromosomes are frequently accompanied by other sex chromosomal abnormalities.

Monosomy of 18q12.3 has been reported in only 16 cases, in one as a mosaic with a normal cell line. Abnormal behaviour, developmental delay, normal measurements, and minor facial anomalies including ptosis, bilateral epicanthus, strabismus, short and slightly down-slanting palpebral fissures, and full cheeks are characteristic manifestations. We report on a 26-month-old girl with del(18)(q12.2q21.1) and typical phenotype. Microsatellite mediated haplotype analysis showed approximately 12 Mb deletion and demonstrated that the deletion was most likely formed during paternal meiosis by a rearrangement between the grandpaternal sister chromatids.

Pseudoisodicentric or asymmetrical dicentric chromosomes 18 are rare findings in clinical cytogenetics. So far, only 8 patients with breakpoints in 18q have been reported and in none of them breakpoints were narrowed down to the molecular level. Here, we describe a 17 months old girl with a perimembranous ventricular septal defect, cleft palate, and minor dysmorphism including hypertelorism, flat nose, frontal bossing and low set ears as well as mosaicism for a cell line with a pseudoisodicentric chromosome 18q and a second cell line with a terminal deletion of 11 Mb in 18q22.2→qter. SNP-array investigation revealed a symmetric breakpoint in 18q22.2 and most likely postzygotic formation from the maternal chromosome 18. Clinical findings in all patients reported so far as well as in the patient presented here were in part overlapping with the clinical phenotypes of trisomy 18 and partial monosomy 18q.

Chromosomal mosaicism is the presence of numerous cell lines with different chromosomal complements in the same individual. Uniparental disomy (UPD) is the inheritance of two homologous chromosomes from the same parent. These genetic anomalies arise from errors in meiosis and/or mitosis and can occur independently or in combination. Due to the formation mechanisms of UPD, low-level or undetected mosaicisms are assumed for a significant number of UPD cases. The pre- and postnatal clinical consequences of mosaicism for chromosomal aberrations and/or UPD depend on the gene content of the involved chromosome. In prenatal evaluation of chromosomal mosaicism and UPD, genetic counseling should be offered before any laboratory testing.

We report on a 30-year-old woman with short stature, completely female external genitalia, primary amenorrhea, bilateral streak gonads, unilateral gonadoblastoma, and a 46,X,del(Y)(q11)/45,X karyotype. Variable levels of mosaicism were found in blood and cultivated fibroblasts from both the skin and ovaries, with the percentage of the 45,X lineage never exceeding 33%. Fluorescence in situ hybridization (FISH) was performed with alpha satellite centromere region probes of the X and Y chromosomes (DXZ1 and DXZ3) as well as with the unique-sequence, locus-specific, sex-determining region of the Y chromosome gene (SRY) and the DXZ1 probes. Each signal was noted for DXZ1 on the X chromosome and for the Y probes on the marker chromosome. Molecular investigations with a panel of PCR markers spread over the whole Y chromosome indicated a deletion breakpoint between sY 78 (interval 4) and sY 151 (interval 5F). No mutation of the high mobility group-box (HMG-box) of the SRY gene could be found following sequence analysis. The phenotype/genotype correlation demonstrates the broad phenotypic range of low-level 45,X mosaicism with the resultant short stature and external female phenotype, despite the presence of SRY in a high proportion of cells in various tissues.

We report on a pair of dizygotic twin boys born after ICSI. One twin was affected with maternal meiosis I-derived free trisomy 21. The other had multiple congenital malformations including a complex heart defect and oesophageal atresia. The advanced maternal age of 37 years predisposed for chromosome 21 meiosis I non-disjunction in twin A. Each of the multiple congenital anomalies in twin B has been described in trisomy 21. However, due to dizygosity demonstrated by a panel of molecular markers mapped on chromosome 21 as well as the results of investigations with 16 short tandem repeat markers localized on various other chromosomes, low level mosaicism or chimerism for this aneuploidy in twin B is unlikely. In addition, the twinning process, which by itself is associated with an increased rate of congenital malformations particularly affecting heart and oesophagus, might be responsible for the multiple congenital anomalies in twin B. Thus, in agreement with the results of several population-based studies from the literature, it appears unlikely that the micromanipulation of ICSI is causally responsible for the different anomalies found in these two boys.

Background Long QT syndrome (LQTS) leads to arrhythmic events and increased risk for sudden cardiac death (SCD). Homozygous KCNH2 mutations underlying LQTS-2 have previously been termed "human HERG knockout" and typically express severe phenotypes. We studied genotype-phenotype correlations of an LQTS type 2 mutation identified in the homozygous index patient from a consanguineous Turkish family after his brother died suddenly during febrile illness. Methods and results Clinical work-up, DNA sequencing, mutagenesis, cell culture, patch-clamp, in silico mathematical modelling, protein biochemistry, confocal microscopy were performed. Genetic analysis revealed a homozygous C-terminal KCNH2 mutation (p.R835Q) in the index patient (QTc ∼506 ms with notched T waves). Parents were I° cousins - both heterozygous for the mutation and clinically unremarkable (QTc ∼447 ms, father and ∼396 ms, mother). Heterologous expression of KCNH2-R835Q showed mildly reduced current amplitudes. Biophysical properties of ionic currents were also only nominally changed with slight acceleration of deactivation and more negative V50 in R835Q-currents. Protein biochemistry and confocal microscopy revealed similar expression patterns and trafficking of WT and R835Q, even at elevated temperature. In silico analysis demonstrated mildly prolonged ventricular action potential duration (APD) compared to WT at a cycle length of 1000 ms. At a cycle length of 350 ms M-cell APD remained stable in WT, but displayed APD alternans in R835Q. Conclusion Kv11.1 channels affected by the C-terminal R835Q mutation display mildly modified biophysical properties, but leads to M-cell APD alternans with elevated heart rate and could precipitate SCD under specific clinical circumstances associated with high heart rates.

OBJECTIVE—To review all cases with segmental and/or complex uniparental disomy (UPD), to study aetiology and mechanisms of formation, and to draw conclusions. DESIGN—Searching published reports in Medline. RESULTS—The survey found at least nine cases with segmental UPD and a normal karyotype, 22 cases with UPD of a whole chromosome and a simple or a non-homologous Robertsonian translocation, eight cases with UPD and two isochromosomes, one of the short arm and one of the long arm of a non-acrocentric chromosome, 39 cases with UPD and an isochromosome of the long arm of two homologous acrocentric chromosomes, one case of UPD and an isochromosome 8 associated with a homozygous del(8)(p23.3pter), and 21 cases with UPD of a whole or parts of a chromosome associated with a complex karyotype. Segmental UPD is formed by somatic recombination (isodisomy) or by trisomy rescue. In the latter mechanism, a meiosis I error is associated with meiotic recombination and an additional somatic exchange between two non-uniparental chromatids. Subsequently, the chromatid that originated from the disomic gamete is lost (iso- and heterodisomy). In cases of UPD associated with one isochromosome of the short arm and one isochromosome of the long arm of a non-acrocentric chromosome and in cases of UPD associated with a true isochromosome of an acrocentric chromosome, mitotic complementation is assumed. This term describes the formation by misdivision at the centromere during an early mitosis of a monosomic zygote. In cases of UPD associated with an additional marker chromosome, either mitotic formation of the marker chromosome in a trisomic zygote or fertilisation of a gamete with a marker chromosome formed in meiosis by a disomic gamete or by a normal gamete and subsequent duplication are possible. CONCLUSIONS—Research in the field of segmental and/or complex UPD may help to explain undiagnosed non-Mendelian disorders, to recognise hotspots for meiotic and mitotic recombinations, and to show that chromosomal segregation is more complex than previously thought. It may also be helpful to map autosomal recessively inherited genes, genes/regions of genomic imprinting, and dysmorphic phenotypes. Last but not least it would improve genetic counselling. Keywords: genomic imprinting; isochromosome; Robertsonian translocation; uniparental disomy (UPD)

We report on a 29-year-old woman with a history of five spontaneous abortions and a balanced complex chromosome rearrangement (CCR) involving break points between chromosomes 8, 11, and 12. Fluorescence in situ hybridisation (FISH) in combination with giemsa trypsin banding techniques were essential for the identification of the breakpoints. In addition, the results were confirmed by 24-colour FISH using the spectral karyotyping system (SKY). The karyotype was 46,XX,t(8;11;12)(8qter→8p10::12p10→12pter;11pter→ 11q14::8p10→8pter;12qter→12p10::11q14→11qter). Application of SKY facilitated detection of all three chromosomes involved and supported the localisation of the breakpoints by a single time and sample saving investigation.

Craniometaphyseal dysplasia (CMD) is a bone dysplasia characterized by overgrowth and sclerosis of the craniofacial bones and abnormal modeling of the metaphyses of the tubular bones. Hyperostosis and sclerosis of the skull may lead to cranial nerve compressions resulting in hearing loss and facial palsy. An autosomal dominant form of the disorder (MIM 123000) was linked to chromosome 5p15.2-p14.1 (ref. 3) within a region harboring the human homolog (ANKH) of the mouse progressive ankylosis (ank) gene. The ANK protein spans the outer cell membrane and shuttles inorganic pyrophosphate (PPi), a major inhibitor of physiologic and pathologic calcification, bone mineralization and bone resorption. Here we carry out mutation analysis of ANKH, revealing six different mutations in eight of nine families. The mutations predict single amino acid substitutions, deletions or insertions. Using a helix prediction program, we propose for the ANK molecule 12 membrane-spanning helices with an alternate inside/out orientation and a central channel permitting the passage of PPi. The mutations occur at highly conserved amino acid residues presumed to be located in the cytosolic portion of the protein. Our results link the PPi channel ANK with bone formation and remodeling.

Intrauterine growth retardation (IUGR) is defined as length and/or weight below the 10th percentile. Etiology and, consequently, long-term outcome are extremely heterogeneous with chromosomal abnormalities found in up to 7%. Recently, uniparental disomy (UPD), i.e. the inheritance of both homologues of one pair of chromosomes from only one parent, was found in an increasing number of children with IUGR. Particularly, UPD of chromosome 7 was found in up to 10% of patients with IUGR and/or a phenotype of primordial growth retardation or Silver-Russell syndrome (SRS), but also UPD of chromosomes 2, 6, 14, 16, 20, and 22 was reported in single cases with IUGR. To evaluate impact and relevance of UPD in children with IUGR we investigated 23 sporadic cases with IUGR subsequently diagnosed as primordial growth retardation (n = 13) or SRS (n = 10) by molecular methods for UPD of chromosomes 2, 6, 14, 16, 20, and 22. No instance of UPD was found. Inheritance of all chromosomes investigated was biparental in all cases. Therefore, we conclude that UPD of these chromosomes is not a major cause of IUGR.

Mosaicism for a derivative 21, der(21;21)(q10;q10), is a rare chromosomal abnormality. Since a normal cell line is present, mitotic origin is considered. Chromosome examination of a female with developmental delay and dysmorphic features compatible with mosaic trisomy 21 revealed a normal cell line and a second cell line with a der(21;21)(q10;q10) [46,XX/46,XX,der(21;21)(q10;q10),+21]. Molecular investigation with a panel of highly polymorphic microsatellites mapping to chromosome 21 demonstrated three different alleles, two of paternal and one of maternal origin. Therefore, either formation of the der(21;21)(q10;q10) during paternal meiosis with subsequent loss of the der(21;21)(q10;q10) and mitotic reduplication of the maternal homologue in the normal cell line, or more likely a zygote with paternally derived trisomy 21 and subsequent mitotic formation of the der(21;21)(q10;q10) have to be considered. This case again shows that mammalian chromosome aberrations may have a more complex mechanism of formation than was previously thought.

Uniparental disomy (UPD) is defined as the inheritance of both homologous chromosomes from only one parent. So far, maternal UPD 7 has been described in 28 cases. Here, we report 4 new cases, present clinical information of 5 cases previously reported by us, and review the clinical and molecular findings of all 32 cases. We found a phenotype characterized by pre- and postnatal growth retardation, occipitofrontal head circumference in the lower normal range, a triangular face, and retarded bone maturation. Findings of the facial gestalt included a high and broad forehead and a pointed chin. A broad mouth with down-turned corners, prominent ears, cafe-au-lait spots, hemihypotrophy, or clinodactyly were rarely present. Psychomotor development was delayed in 6 cases. The clinical findings strikingly resemble the phenotype of the heterogeneous Silver-Russell syndrome (SRS). Other anomalies were less frequently found than in SRS. Molecular investigations revealed 11 cases with isodisomy and 17 cases with heterodisomy. In 4 cases this information was not available. From the allelic distribution of the microsatellites investigated, 9 cases might be the consequence of an error at maternal meiosis I, and 6 cases might be due to non-disjunction at maternal meiosis II. Three of the 17 heterodisomic cases had trisomy 7 in chorionic villi, in the remaining cases no prenatal diagnosis through chorionic villus sampling was reported. Conclusion Maternal UPD 7 should be investigated in children with pre- and postnatal growth retardation and a facial gestalt characterized by a high and broad forehead and a pointed chin, as well as in confined placental mosaicism for trisomy 7.

Williams-Beuren syndrome (WBS) results from a deletion of 7q11.23 in 90-95% of all clinically typical cases. Clinical manifestation can be variable and therefore, deletion size, inherited elastin (ELN) and LIM kinase 1 (LIMK1) alleles, gender, and parental origin of deletion have been investigated for associations with clinical outcome. In an analysis of 85 confirmed deletion cases, no statistically significant associations were found after Bonferroni's correction for multiple pairwise comparisons. Furthermore, the present data do not support presence of imprinted genes in the WBS common deletion despite a nonsignificant excess of maternal over paternal deletions. Maternal deletion cases were more likely to have a large head circumference in the present data. Also, pairwise comparisons between individual WBS clinical features have been conducted and revealed significant associations between (1) low birth weight and poor postnatal weight gain (