Wiedemann-Steiner syndrome as a major cause of syndromic intellectual disability: A study of 33 French cases.

Wiedemann-Steiner syndrome (WSS) is a rare syndromic condition in which intellectual disability (ID) is associated with hypertrichosis cubiti, short stature, and characteristic facies. Following the identification of the causative gene (KMT2A) in 2012, only 31 cases of WSS have been described precisely in the literature. We report on 33 French individuals with a KMT2A mutation confirmed by targeted gene sequencing, high-throughput sequencing or exome sequencing. Patients' molecular and clinical features were recorded and compared with the literature data. On the molecular level, we found 29 novel mutations. We observed autosomal dominant transmission of WSS in 3 families and mosaicism in one family. Clinically, we observed a broad phenotypic spectrum with regard to ID (mild to severe), the facies (typical or not of WSS) and associated malformations (bone, cerebral, renal, cardiac and ophthalmological anomalies). Hypertrichosis cubiti that was supposed to be pathognomonic in the literature was found only in 61% of our cases. This is the largest series of WSS cases yet described to date. A majority of patients exhibited suggestive features, but others were less characteristic, only identified by molecular diagnosis. The prevalence of WSS was higher than expected in patients with ID, suggesting than KMT2A is a major gene in ID.

A new highly penetrant form of obesity due to deletions on chromosome 16p11.2.

Obesity has become a major worldwide challenge to public health, owing to an interaction between the Western 'obesogenic' environment and a strong genetic contribution. Recent extensive genome-wide association studies (GWASs) have identified numerous single nucleotide polymorphisms associated with obesity, but these loci together account for only a small fraction of the known heritable component. Thus, the 'common disease, common variant' hypothesis is increasingly coming under challenge. Here we report a highly penetrant form of obesity, initially observed in 31 subjects who were heterozygous for deletions of at least 593 kilobases at 16p11.2 and whose ascertainment included cognitive deficits. Nineteen similar deletions were identified from GWAS data in 16,053 individuals from eight European cohorts. These deletions were absent from healthy non-obese controls and accounted for 0.7% of our morbid obesity cases (body mass index (BMI) >or= 40 kg m(-2) or BMI standard deviation score >or= 4; P = 6.4 x 10(-8), odds ratio 43.0), demonstrating the potential importance in common disease of rare variants with strong effects. This highlights a promising strategy for identifying missing heritability in obesity and other complex traits: cohorts with extreme phenotypes are likely to be enriched for rare variants, thereby improving power for their discovery. Subsequent analysis of the loci so identified may well reveal additional rare variants that further contribute to the missing heritability, as recently reported for SIM1 (ref. 3). The most productive approach may therefore be to combine the 'power of the extreme' in small, well-phenotyped cohorts, with targeted follow-up in case-control and population cohorts.

A novel microdeletion syndrome at 3q13.31 characterised by developmental delay, postnatal overgrowth, hypoplastic male genitals, and characteristic facial features.

BACKGROUND: Congenital deletions affecting 3q11q23 have rarely been reported and only five cases have been molecularly characterised. Genotype-phenotype correlation has been hampered by the variable sizes and breakpoints of the deletions. In this study, 14 novel patients with deletions in 3q11q23 were investigated and compared with 13 previously reported patients. METHODS: Clinical data were collected from 14 novel patients that had been investigated by high resolution microarray techniques. Molecular investigation and updated clinical information of one cytogenetically previously reported patient were also included. RESULTS: The molecular investigation identified deletions in the region 3q12.3q21.3 with different boundaries and variable sizes. The smallest studied deletion was 580 kb, located in 3q13.31. Genotype-phenotype comparison in 24 patients sharing this shortest region of overlapping deletion revealed several common major characteristics including significant developmental delay, muscular hypotonia, a high arched palate, and recognisable facial features including a short philtrum and protruding lips. Abnormal genitalia were found in the majority of males, several having micropenis. Finally, a postnatal growth pattern above the mean was apparent. The 580 kb deleted region includes five RefSeq genes and two of them are strong candidate genes for the developmental delay: DRD3 and ZBTB20. CONCLUSION: A newly recognised 3q13.31 microdeletion syndrome is delineated which is of diagnostic and prognostic value. Furthermore, two genes are suggested to be responsible for the main phenotype.

Trisomy 7 mosaicism prenatally misdiagnosed and maternal uniparental disomy in a child with pigmentary mosaicism and Russell- Silver syndrome.

Prenatal diagnosis of true mosaic trisomy 7 is rare in amniotic fluid and can be misinterpreted as pseudomosaic. The phenotype is highly variable and may be modified by a maternal uniparental disomy of chromosome 7 leading to mild Russell-Silver syndrome (RSS). We report here the third postnatal case of mosaic trisomy 7 with maternal uniparental disomy of chromosome 7 in a boy presenting a mild RSS. Fetal karyotype performed in amniocentesis for intrauterine growth retardation was considered normal. Mosaic trisomy 7 was diagnosed after birth, on fibroblasts karyotype performed for blaschkolinear pigmentary skin anomalies and failure to thrive. Maternal uniparental disomy of chromosome 7 was observed in blood sample. Retrospectively, trisomic 7 cells were identified in one prenatal long-term flask culture revealing a prenatal diagnosis failure. This report emphasizes the difficulty of assessing fetal mosaicism and distinguishing it from pseudomosaicism in cultured amniocytes. It is important to search for uniparental disomy as an indirect clue of trisomy 7 mosaicism and a major prognosis element. Although there are only few prenatal informative cases, detection of trisomy 7 in amniocentesis appears to be associated with a relatively good outcome when maternal uniparental disomy has been ruled out.

Microdeletion at chromosome 4q21 defines a new emerging syndrome with marked growth restriction, mental retardation and absent or severely delayed speech.

BACKGROUND Genome-wide screening of large patient cohorts with mental retardation using microarray-based comparative genomic hybridisation (array-CGH) has recently led to identification several novel microdeletion and microduplication syndromes. METHODS Owing to the national array-CGH network funded by the French Ministry of Health, shared information about patients with rare disease helped to define critical intervals and evaluate their gene content, and finally determine the phenotypic consequences of genomic array findings. RESULTS In this study, nine unrelated patients with overlapping de novo interstitial microdeletions involving 4q21 are reported. Several major features are common to all patients, including neonatal muscular hypotonia, severe psychomotor retardation, marked progressive growth restriction, distinctive facial features and absent or severely delayed speech. The boundaries and the sizes of the nine deletions are different, but an overlapping region of 1.37 Mb is defined; this region contains five RefSeq genes: PRKG2, RASGEF1B, HNRNPD, HNRPDL and ENOPH1. DISCUSSION Adding new individuals with similar clinical features and 4q21 deletion allowed us to reduce the critical genomic region encompassing two genes, PRKG2 and RASGEF1B. PRKG2 encodes cGMP-dependent protein kinase type II, which is expressed in brain and in cartilage. Information from genetically modified animal models is pertinent to the clinical phenotype. RASGEF1B is a guanine nucleotide exchange factor for Ras family proteins, and several members have been reported as key regulators of actin and microtubule dynamics during both dendrite and spine structural plasticity. CONCLUSION Clinical and molecular delineation of 4q21 deletion supports a novel microdeletion syndrome and suggests a major contribution of PRKG2 and RASGEF1B haploinsufficiency to the core phenotype.

Delineation of 15q13.3 microdeletions.

The increasing use of array-comparative genomic hybridization (array-CGH) to identify copy number variations (CNVs) in patients with developmental delay (DD), mental retardation and/or dysmorphic features has allowed the recent recognition of numerous genomic imbalances, including the 15q13.3 microdeletion. Patients with this microdeletion generally present with relatively consistent breakpoints at BP4 and BP5, which include the CHRNA7 gene. About 100 index cases have been reported since the first publication in 2008. This large number of patients ascertained through highly variable samples has been necessary to describe the full phenotypic spectrum of this microdeletion, ranging from mental retardation with dysmorphic features, epilepsy, neuropsychiatric disturbances with or without cognitive impairment to complete absence of anomalies. Here, we describe a collaborative study reporting a new cohort of 12 index patients and 13 relatives carrying a heterozygous BP4-BP5 microdeletion out of a series of 4625 patients screened by array-CGH for DD. We confirm the clinical expressivity of the disease as well as the incomplete penetrance in seven families. We showed through a review of the literature that males are more likely to be symptomatic. Sequence analysis of CHRNA7 yielded no data to support the unmasking of recessive variants as a cause of phenotypic variability. We also report the first patient carrying a 15q13.3 homozygous microdeletion inherited from both parents. He had severe epileptic encephalopathy with retinopathy, autistic features and choreoathetosis. Besides the classical approximately 1.5 Mb BP4-BP5 microdeletion, we also describe three index patients and two relatives with a smaller 500 kb microdeletion, including the CHRNA7 gene.

Mutational spectrum of CDKL5 in early-onset encephalopathies: a study of a large collection of French patients and review of the literature.

The CDKL5 gene has been implicated in the molecular etiology of early-onset intractable seizures with infantile spasms (IS), severe hypotonia and atypical Rett syndrome (RTT) features. So far, 48 deleterious alleles have been reported in the literature. We screened the CDKL5 gene in a cohort of 177 patients with early-onset seizures, including 30 men and 10 girls with Aicardi syndrome. The screening was negative for all men as well as for women with Aicardi syndrome, excluding the CDKL5 gene as a candidate for this neurodevelopmental disorder. We report 11 additional de novo mutations in CDKL5 in female patients. For the first time, the MLPA approach allowed the identification of a partial deletion encompassing the promoter and the first two exons of CDKL5. The 10-point mutations consist of five missenses (with recurrent amino acid changes at p.Ala40 and p.Arg178), four splicing variants and a 1-base pair duplication. We present a review of all mutated alleles published in the literature. In our study, the overall frequency of mutations in CDKL5 in women with early-onset seizures is around 8.6%, a result comparable with previous reports. Noteworthy, the CDKL5 mutation rate is high (28%) in women with early-onset seizures and IS.

Genotype phenotype correlation of 30 patients with Smith-Magenis syndrome (SMS) using comparative genome hybridisation array: cleft palate in SMS is associated with larger deletions.

BACKGROUND: Smith-Magenis syndrome (SMS) is rare (prevalence 1 in 25 000) and is associated with psychomotor delay, a particular behavioural pattern and congenital anomalies. SMS is often due to a chromosomal deletion of <4 Mb at the 17p11.2 locus, leading to haploinsufficiency of numerous genes. Mutations of one of these gemes, RAI1, seems to be responsible for the main features found with heterozygous 17p11.2 deletions. METHODS: We studied DNA from 30 patients with SMS using a 300 bp amplimers comparative genome hybridisation array encompassing 75 loci from a 22 Mb section from the short arm of chromosome 17. RESULTS: Three patients had large deletions (10%). Genotype-phenotype correlation showed that two of them had cleft palate, which was not found in any of the other patients with SMS (p<0.007, Fisher's exact test). The smallest extra-deleted region associated with cleft palate in SMS is 1.4 Mb, contains <16 genes and is located at 17p11.2-17p12. Gene expression array data showed that the ubiquitin B precursor (UBB) is significantly expressed in the first branchial arch in the fourth and fifth weeks of human development. CONCLUSION: These data support UBB as a good candidate gene for isolated cleft palate.

[Birth of a child with Down syndrome: parental choice or failure of screening policy?]. / Naissance d'un enfant porteur de trisomie 21: choix parental ou défaut de la politique de dépistage ?

OBJECTIVES: Birth of a child with Down syndrome (DS) can follow parental choice or failure of screening. The objective of this work is to describe the circumstances of births of children with DS in a French perinatal health network. METHODS: Retrospective multicentric study, with prospective trial registration of all children born alive with DS, between 2010 and 2013. RESULTS: Sixty-three children were born with DS. Complete screening was performed by 61 % of patients, incomplete screening by 29 % of patients and no screening test by 10 %. Among these births, 50 % occurred following parental choice, 40 % following failure of screening and for 10 %, parental choice concerning screening was unknown. False negative had often calculating risk close to 1/1000. CONCLUSION: In this study, the birth of a child with DS occurred following parental choice in half of cases. It's necessary, to optimize the follow-up, to document in medical records the medical information and parental choice concerning DS screening and data of screening when this was done.

Identification and molecular characterization of a small 11q23.3 de novo duplication in a patient with Rett syndrome manifestations.

We report on an interstitial duplication of the long arm of chromosome 11 [46XX,dup(11) (q23.3)] in a girl with atypical Rett syndrome (RS). This case was discovered during a systematic cytogenetic study of RS. Fluorescent in situ hybridization including total chromosome painting and use of regional specific YAC, cosmid and plasmid probes, was used to confirm the chromosome 11q involvement and to identify the landmarks of the smallest 11q duplication reported to date. The findings are compared to cases of trisomy 11q reported previously, all of which have a larger duplication and different clinical manifestations. Surprisingly, mental retardation and behavior disorders are less severe in these cases.

Homologous T and B cells immortalized in vitro by the Epstein-Barr virus exhibit differential genetical and functional features.

After in vitro EBV infection of peripheral blood lymphocytes (PBL), we previously obtained IL-2-independent T-cell lines expressing EBNA1 and LMP1 viral latent genes. One tumorigenic clone, NC5, was further characterized for chromosomal abnormalities, rearrangement and expression of oncogenes, and constitutive or induced activation of cellular transduction pathways. NC5 as well as TC cells derived from an NC5-induced tumor exhibited the same few chromosomal abnormalities absent in normal PBL and B-cell lines (LCLs) from the same donor. No rearrangement or altered expression of C-MYC, BCL-2 and NF-KB2 oncogenes could be detected. In contrast, we found high levels of BCL-X and thioredoxin (TRX), as markers of EBV infection or T-cell activation/transformation status. No constitutive activation of NF-kappa B or STAT transcriptional complexes was observed in these cells. For NF-kappa B, this was in apparent contradiction with its reported inducibility mediated by LMP1, taking into account that NF-kappa B was still inducible by TNF alpha or PMA and ionomycin. Our results highlight independence of EBV protein-mediated transformation towards classical cellular pathways in T-lymphocytes.

Characteristics and development of the tyrosine-rich protein granules in the adipose tissue of the Curculionid beetle Sitophilus oryzae.

In the Curculionid beetle Sitophilus oryzae, the fat body is composed of one type of adipocyte, interstitial cells and oenocytes. Synthesis and storage of tyrosine-rich-protein granules (TRPG) in adipocytes are observed during all the larval and prepupal stages (except the first larval instar which has not been studied). They appear first in the posterior part of the fat body, around the nucleus of adipocytes. They progressively invade the cytoplasm. In the young pupa, TRPG are present in every part of the body, including the head and the appendages in formation. TRPG grow in size by fusing together. Their mean diameter is 6 microm, but some of them reach up to 50 microm. They present a basic core and an acidic periphery. Their charge in tyrosine increases until the prepupa. They are APS and lipid negative and contain no RNA. During metamorphosis they take on a reticulated structure, evoking a golf ball, and disintegrate into small granules, the tyrosine content of which diminishes drastically, especially in contact with epidermal cells, whence tyrosine is probably transferred. TRPG in S. oryzae contain 16 different insoluble proteins. Five of them are tyrostaurins characterized by their very high content in tyrosine (up to 27%) and their strict insolubility in aqueous solution. Arylphorin-like proteins have not been detected in S. oryzae granules.

Antley-Bixler syndrome: case report and review of the literature.

A female newborn presenting a malformative syndrome which groups trapezoidocephaly, midfacial hypoplasia, radiohumeral synostosis, multiple joint contractures and femoral bowing is described as being affected of an Antley-Bixler syndrome. We compare this case with the seventeen others cases reported.

[Smith-Magenis syndrome]. / Le syndrome de Smith-Magenis.

Smith-Magenis syndrome is caused by a 17p11.2 deletion. It associates mental retardation, facial dysmorphism and brachydactyly; aberrant behavior and major sleep problems are present in 70% of the cases. It is probably under-diagnosed because the facial abnormalities are mild and the behavioral problems with hyperactivity and self-injuries are dominant, leading to the diagnosis of psychiatric pathology. However these behavioral problems are sufficiently characterized to allow the diagnosis of the syndrome and look for a 17p11.2 microdeletion. Otorhinolaryngologic, ophthalmologic, cardiac and renal abnormalities can be associated and their evaluation is necessary. Smith-Magenis syndrome is considered as a contiguous gene syndrome. Genes have been mapped and isolated to the critical region, but their participation in the pathogenesis of the syndrome remains unclear.

[Fragile X syndrome is still unrecognized: efficacy of molecular diagnosis in mentally retarded probands]. / Le syndrome X fragile est encore méconnu: efficacité du diagnostic moléculaire chez les proposants avec retard mental.

BACKGROUND: The fragile X mental retardation syndrome is the most common cause of inherited mental retardation. Identification of the unstable mutation responsible for the disease has allowed the design of a fully reliable molecular test for the diagnosis of the disease and for genetic counselling (identification of clinically normal carriers and prenatal diagnosis). We started in July 1991 to search for the mutation in mentally retarded probands, with no known cause for their phenotype. We present the results of a 42-month experience. POPULATION AND METHODS: One thousand and one hundred fourty-nine probands were analysed. In case of a positive diagnosis, an extension of the molecular study to relatives was proposed. DNA samples were studied by Southern blot following EcoRI or EcoRI + EagI digestion. Clinical data were collected from referring clinicians. RESULTS: Seventy-three carriers of a full mutation were identified, belonging to 52 families. The mean age of the fragile X probands was 16 +/- 14 years, which is very surprising for a disease that causes significant manifestations by the age of 2 to 3 years. This indicates an insufficient knowledge about this disease in France. Most of the demands for the test were from clinical geneticists. This diagnosis is of major importance for genetic counselling, as illustrated by the following study of 108 women at risk in these families. CONCLUSIONS: The importance of an early diagnosis followed by an extended family study, for carrier screening and prevention of this severe disease, justifies molecular testing on any child with mental retardation or significant language delay of unknown cause, in the absence of clinical signs formally excluding a fragile X diagnosis.

[Rothmund-Thomson syndrome, trisomy 8 mosaicism and RECQ4 gene mutation]. / Syndrome de Rothmund-Thomson, trisomie 8 en mosaïque et mutation du gène RECQ4.

BACKGROUND: We report a case of Rothmund-Thomson syndrome associated with a trisomy 8 mosaicism, and RECQ4 gene mutation. OBSERVATION: An 18-year-old man presented with a poikiloderma affecting photoexposed areas and the buttocks. This lesions appeared during the first year of life and was secondly associated with alopecia, sparse body hair, keratosis, and warts. He also had proportional short stature, thumb and patella aplasia, particular facies, and plantar malformations. Cytogenetic studies evidenced chromosomal instability and trisomy 8 mosaicism. The DNA repair capacity was normal. A mutation in RECQ4 helicase gene was found. DISCUSSION: Rothmund-Thomson syndrome is a rare hereditary syndrome characterized by early onset of poikiloderma. Patients exhibit variable features including skeletal abnormalities, juvenile cataracts, photosensitivity, and a higher than expected incidence of cutaneous or extracutaneous malignancies. Genetic patterns found in Rothmund-Thomson syndrome are heterogeneous. Normal karyotypes have been demonstrated in many patients. Various karyotypic abnormalities or reduced DNA repair was seen in others. Recently, five patients with Rothmund-Thomson syndrome were shown to segregate for mutations in RECQ4 helicase gene. Thus, clinical and genetic features in Rothmund-Thomson syndrome are polymorphous. Therefore, it could be interesting to correlate genotype and phenotype.

Duplications in RB1CC1 are associated with schizophrenia; identification in large European sample sets.

Schizophrenia (SCZ) is a severe and debilitating neuropsychiatric disorder with an estimated heritability of ~80%. Recently, de novo mutations, identified by next-generation sequencing (NGS) technology, have been suggested to contribute to the risk of developing SCZ. Although these studies show an overall excess of de novo mutations among patients compared with controls, it is not easy to pinpoint specific genes hit by de novo mutations as actually involved in the disease process. Importantly, support for a specific gene can be provided by the identification of additional alterations in several independent patients. We took advantage of existing genome-wide single-nucleotide polymorphism data sets to screen for deletions or duplications (copy number variations, CNVs) in genes previously implicated by NGS studies. Our approach was based on the observation that CNVs constitute part of the mutational spectrum in many human disease-associated genes. In a discovery step, we investigated whether CNVs in 55 candidate genes, suggested from NGS studies, were more frequent among 1637 patients compared with 1627 controls. Duplications in RB1CC1 were overrepresented among patients. This finding was followed-up in large, independent European sample sets. In the combined analysis, totaling 8461 patients and 112 871 controls, duplications in RB1CC1 were found to be associated with SCZ (P=1.29 × 10(-5); odds ratio=8.58). Our study provides evidence for rare duplications in RB1CC1 as a risk factor for SCZ.