A homozygous DPM3 mutation in a patient with alpha-dystroglycan-related limb girdle muscular dystrophy.

Defects of O-linked glycosylation of alpha-dystroglycan cause a wide spectrum of muscular dystrophies ranging from severe congenital muscular dystrophy associated with abnormal brain and eye development to mild limb girdle muscular dystrophy. We report a female patient who developed isolated pelvic girdle muscle weakness and wasting, which became symptomatic at age 42. Exome sequencing uncovered a homozygous c.131T > G (p.Leu44Pro) substitution in DPM3, encoding dolichol-P-mannose (DPM) synthase subunit 3, leading to a 50% reduction of enzymatic activity. Decreased availability of DPM as an essential donor substrate for protein O-mannosyltransferase (POMT) 1 and 2 explains defective skeletal muscle alpha-dystroglycan O-glycosylation. Our findings show that DPM3 mutations may lead to an isolated and mild limb girdle muscular dystrophy phenotype without cardiomyopathy.

Search for ReCQL4 mutations in 39 patients genotyped for suspected Rothmund-Thomson/Baller-Gerold syndromes.

Three overlapping conditions, namely Rothmund-Thomson (RTS), Baller-Gerold (BGS) and RAPADILINO syndromes, have been attributed to RECQL4 mutations. Differential diagnoses depend on the clinical presentation, but the numbers of known genes remain low, leading to the widespread prescription of RECQL4 sequencing. The aim of our study was therefore to determine the best clinical indicators for the presence of RECQL4 mutations in a series of 39 patients referred for RECQL4 molecular analysis and belonging to the RTS (27 cases) and BGS (12 cases) spectrum. One or two deleterious RECQL4 mutations were found in 10/27 patients referred for RTS diagnosis. Clinical and molecular reevaluation led to a different diagnosis in 7/17 negative cases, including Clericuzio-type poikiloderma with neutropenia, hereditary sclerosing poikiloderma, and craniosynostosis/anal anomalies/porokeratosis. No RECQL4 mutations were found in the BGS group without poikiloderma, confirming that RECQL4 sequencing was not indicated in this phenotype. One chromosomal abnormality and one TWIST mutation was found in this cohort. This study highlights the search for differential diagnoses before the prescription of RECQL4 sequencing in this clinically heterogeneous group. The combination of clinically defined subgroups and next-generation sequencing will hopefully bring to light new molecular bases of syndromes with poikiloderma, as well as BGS without poikiloderma.

Phenotype and genotype in 101 males with X-linked creatine transporter deficiency.

BACKGROUND: Creatine transporter deficiency is a monogenic cause of X-linked intellectual disability. Since its first description in 2001 several case reports have been published but an overview of phenotype, genotype and phenotype--genotype correlation has been lacking. METHODS: We performed a retrospective study of clinical, biochemical and molecular genetic data of 101 males with X-linked creatine transporter deficiency from 85 families with a pathogenic mutation in the creatine transporter gene (SLC6A8). RESULTS AND CONCLUSIONS: Most patients developed moderate to severe intellectual disability; mild intellectual disability was rare in adult patients. Speech language development was especially delayed but almost a third of the patients were able to speak in sentences. Besides behavioural problems and seizures, mild to moderate motor dysfunction, including extrapyramidal movement abnormalities, and gastrointestinal problems were frequent clinical features. Urinary creatine to creatinine ratio proved to be a reliable screening method besides MR spectroscopy, molecular genetic testing and creatine uptake studies, allowing definition of diagnostic guidelines. A third of patients had a de novo mutation in the SLC6A8 gene. Mothers with an affected son with a de novo mutation should be counselled about a recurrence risk in further pregnancies due to the possibility of low level somatic or germline mosaicism. Missense mutations with residual activity might be associated with a milder phenotype and large deletions extending beyond the 3' end of the SLC6A8 gene with a more severe phenotype. Evaluation of the biochemical phenotype revealed unexpected high creatine levels in cerebrospinal fluid suggesting that the brain is able to synthesise creatine and that the cerebral creatine deficiency is caused by a defect in the reuptake of creatine within the neurones.

Systematic molecular and cytogenetic screening of 100 patients with marfanoid syndromes and intellectual disability.

The association of marfanoid habitus (MH) and intellectual disability (ID) has been reported in the literature, with overlapping presentations and genetic heterogeneity. A hundred patients (71 males and 29 females) with a MH and ID were recruited. Custom-designed 244K array-CGH (Agilent®; Agilent Technologies Inc., Santa Clara, CA) and MED12, ZDHHC9, UPF3B, FBN1, TGFBR1 and TGFBR2 sequencing analyses were performed. Eighty patients could be classified as isolated MH and ID: 12 chromosomal imbalances, 1 FBN1 mutation and 1 possibly pathogenic MED12 mutation were found (17%). Twenty patients could be classified as ID with other extra-skeletal features of the Marfan syndrome (MFS) spectrum: 4 pathogenic FBN1 mutations and 4 chromosomal imbalances were found (2 patients with both FBN1 mutation and chromosomal rearrangement) (29%). These results suggest either that there are more loci with genes yet to be discovered or that MH can also be a relatively non-specific feature of patients with ID. The search for aortic complications is mandatory even if MH is associated with ID since FBN1 mutations or rearrangements were found in some patients. The excess of males is in favour of the involvement of other X-linked genes. Although it was impossible to make a diagnosis in 80% of patients, these results will improve genetic counselling in families.

Deficiency of Subunit 6 of the Conserved Oligomeric Golgi Complex (COG6-CDG): Second Patient, Different Phenotype.

We describe a 27-month-old girl with COG6 deficiency. She is the first child of healthy consanguineous Moroccan parents. She presented at birth with dysmorphic features including microcephaly, post-axial polydactyly, broad palpebral fissures, retrognathia, and anal anteposition. The clinical phenotype was further characterised by multiorgan involvement including mild psychomotor retardation, and microcephaly, chronic inflammatory bowel disease, micronodular liver cirrhosis, associated with life-threatening and recurrent infections due to combined T- and B-cell dysfunction and neutrophil dysfunction.Mutation analysis showed the patient to be homozygous for the c.G1646T mutation in the COG6 gene. She is the second reported patient with a deficiency of subunit 6 of the COG complex. Although both patients are homozygous for the same mutation, they present a markedly different clinical picture. Indeed immunodeficiency as well as inflammatory bowel disease has not been described previously in patients with any COG-CDG.

IRF6 Screening of Syndromic and a priori Non-Syndromic Cleft Lip and Palate Patients: Identification of a New Type of Minor VWS Sign.

Van der Woude syndrome (VWS), caused by dominant IRF6 mutation, is the most common cleft syndrome. In 15% of the patients, lip pits are absent and the phenotype mimics isolated clefts. Therefore, we hypothesized that some of the families classified as having non-syndromic inherited cleft lip and palate could have an IRF6 mutation. We screened in total 170 patients with cleft lip with or without cleft palate (CL/P): 75 were syndromic and 95 were a priori part of multiplex non-syndromic families. A mutation was identified in 62.7 and 3.3% of the patients, respectively. In one of the 95 a priori non-syndromic families with an autosomal dominant inheritance (family B), new insights into the family history revealed the presence, at birth, of lower lip pits in two members and the diagnosis was revised as VWS. A novel lower lip sign was observed in one individual in this family. Interestingly, a similar lower lip sign was also observed in one individual from a 2nd family (family A). This consists of 2 nodules below the lower lip on the external side. In a 3rd multiplex family (family C), a de novo mutation was identified in an a priori non-syndromic CL/P patient. Re-examination after mutation screening revealed the presence of a tiny pit-looking lesion on the inner side of the lower lip leading to a revised diagnosis of VWS. On the basis of this data, we conclude that IRF6 should be screened when any doubt rises about the normality of the lower lip and also if a non-syndromic cleft lip patient (with or without cleft palate) has a family history suggestive of autosomal dominant inheritance.

Expanding CEP290 mutational spectrum in ciliopathies.

Ciliopathies are an expanding group of rare conditions characterized by multiorgan involvement, that are caused by mutations in genes encoding for proteins of the primary cilium or its apparatus. Among these genes, CEP290 bears an intriguing allelic spectrum, being commonly mutated in Joubert syndrome and related disorders (JSRD), Meckel syndrome (MKS), Senior-Loken syndrome and isolated Leber congenital amaurosis (LCA). Although these conditions are recessively inherited, in a subset of patients only one CEP290 mutation could be detected. To assess whether genomic rearrangements involving the CEP290 gene could represent a possible mutational mechanism in these cases, exon dosage analysis on genomic DNA was performed in two groups of CEP290 heterozygous patients, including five JSRD/MKS cases and four LCA, respectively. In one JSRD patient, we identified a large heterozygous deletion encompassing CEP290 C-terminus that resulted in marked reduction of mRNA expression. No copy number alterations were identified in the remaining probands. The present work expands the CEP290 genotypic spectrum to include multiexon deletions. Although this mechanism does not appear to be frequent, screening for genomic rearrangements should be considered in patients in whom a single CEP290 mutated allele was identified.

Cardiofaciocutaneous (CFC) syndrome associated with muscular coenzyme Q10 deficiency.

The cardiofaciocutaneous (CFC) syndrome is characterized by congenital heart defect, developmental delay, peculiar facial appearance with bitemporal constriction, prominent forehead, downslanting palpebral fissures, curly sparse hair and abnormalities of the skin. CFC syndrome phenotypically overlaps with Noonan and Costello syndromes. Mutations of several genes (PTPN11, HRAS, KRAS, BRAF, MEK1 and MEK2), involved in the mitogen-activated protein kinase (MAPK) pathway, have been identified in CFC-Costello-Noonan patients. Coenzyme Q10 (CoQ10), a lipophilic molecule present in all cell membranes, functions as an electron carrier in the mitochondrial respiratory chain, where it transports electrons from complexes I and II to complex III. CoQ10 deficiency is a rare treatable mitochondrial disorder with various neurological (cerebellar ataxia, myopathy, epilepsy, mental retardation) and extraneurological (cardiomyopathy, nephropathy) signs that are responsive to CoQ10 supplementation. We report the case of a 4-year-old girl who presented a CFC syndrome, confirmed by the presence of a pathogenic R257Q BRAF gene mutation, together with a muscular CoQ10 deficiency. Her psychomotor development was severely impaired, hindered by muscular hypotonia and ataxia, both improving remarkably after CoQ10 treatment. This case suggests that there is a functional connection between the MAPK pathway and the mitochondria. This could be through the phosphorylation of a nuclear receptor essential for CoQ10 biosynthesis. Another hypothesis is that K-Ras, one of the proteins composing the MAPK pathway, might be recruited into the mitochondria to promote apoptosis. This case highlights that CoQ10 might contribute to the pathogenesis of CFC syndrome.

Familial CHARGE syndrome because of CHD7 mutation: clinical intra- and interfamilial variability.

CHARGE syndrome (OMIM #214800) is a multiple malformation syndrome with distinctive diagnostic criteria, usually because of CHD7 (chromodomain helicase DNA binding 7) haploinsufficiency. Familial occurrence of CHARGE syndrome is rare. We report six patients from two Caucasian families (both with one parent and two children) affected by mild to severe CHARGE syndrome. Direct sequencing of the CHD7 gene was performed in these two unrelated families. A mutation in exon 8 (c.2501C>T - p.S834F) in first chromodomain was found in family A and a nonsense mutation in exon 2 (c.469C>T - p.R157X) in family B. Both mutations are de novo in the parents. In family A, the elder son had bilateral cleft lip and palate, esophageal atresia with fistula, complex heart defect and vertebral abnormalities, while the younger had a posterior coloboma. Their mother had asymptomatic vestibular dysfunction and retinal coloboma, identified after the molecular diagnosis of her children. In family B, both affected children had severe expression of CHARGE syndrome. The father carrying the mutation only had asymmetric anomaly of the pinnae. These familial reports describe the intrafamilial variability of CHARGE syndrome, and underline the presence of CHD7 mutations in patients who do not fit the 'classical clinical criteria' for CHARGE syndrome.

The t(4;8) is mediated by homologous recombination between olfactory receptor gene clusters, but other 4p16 translocations occur at random.

The t(4;8)(p16;p23) is the second most common constitutional chromosomal translocation and is caused by an ectopic meiotic recombination between the olfactory receptor gene clusters (ORGC), located on chromosome 4p and 8p. Given that ORGCs are scattered across the genome and make-up about 0.1% of the human genome we reasoned that translocations between 4p16 and other chromosomes might be mediated by ectopic recombination between different ORGC. In 13 patients, we mapped the breakpoints of either a balanced or unbalanced translocation between chromosome 4p16 and different chromosomes. For all four t(4;8) cases, the breakpoints fall within the 4p and 8pter ORGC, confirming that non-allelic homologous recombination (NAHR) between the ORGC is the main mechanism of the t(4;8) formation. For the nine other translocations, the breakpoints on chromosome 4 mapped to different loci, one of them within the ORGC and in two flanking the ORGC. In these three cases, the translocation breakpoint at the reciprocal chromosome did not contain ORGC sequences. We conclude that only the t(4;8) is mediated by NAHR between ORGC.

[The genetic approaches of the disorders of the child]. / Les approches génétiques des affections de l'enfant.

Genetics, which encompasses cytogenetic, molecular genetics, genetic of populations, pharmacogenetics and gene therapy, become as numerous and almost independent applications (fields). Deriving from the original questions on the origin and mechanisms of diseases, these represent essential tools to better understand physiopathogenesis. Cytogenetics (Chromosomes study, aberrations and their impact on the apparition of diseases) and genomics (the understand of the structure, organisation and DNA expression) are dedicated to clinical genetics as diagnostic and basic science improvements. The identification of new mechanisms of diseases were responsible for the creation of new tools which allow in turn to precise the intimate and underlying processes of diseases or syndromes. Due to the explosion of findings and research programs on fetal, embryologic and pediatric fields, laboratory and reference centers were build. Any child identified as carrier and/or affected from a pathogenic mutation became the primary step for the development of fetal, prenatal and preimplantatory medicines. Ethics came into play since responsibilities for 'do not harm', 'eugenism' temptations and 'individual life' with respect to medical laws should be guaranteed. These are part of the geneticist tasks and the reasons for professionalisation as for teaching genetics as part of medical traineeships that Paediatrics, among others, represents. The present review will systematically describe the principles of these different genetic fields.

Bony syngnathia, vertebral segmentation defect, coloboma, microcephaly and mental retardation: confirmation of Dobrow syndrome and review of syndromal syngnathias.

Congenital bony fusion of the maxilla and mandible is a rare condition. Two classifications were previously proposed dealing exclusively with craniofacial malformations. Most of the reported cases to date represent either aglossia-adactylia or hemifacial microsomia syndromes. We report a young girl with bony syngnathia associated with multiple defects (severe microcephaly, coloboma, vertebral segmentation defects), growth and mental delay. This patient is very similar to the patient described by Dobrow in 1983 and confirms the existence of this extremely rare disorder.

Sporadic case of trichorhinophalangeal syndrome type III in a European patient.

Trichorhinophalangeal syndrome type III (TRP III) shares common traits with TRP I and II, including sparse hair, a "pear-shaped" nose, osteodysplasia with cone-shaped epiphyses, and autosomal dominant inheritance, but is distinguished by the presence of severe brachydactyly. TRP III was first described in 1984 in Japanese patients, one sporadic case [Sugio and Kajii, 1984: Am. J. Med. Genet. 19:741-753,1984] and two families [Niikawa and Kamei, 1986: Am. J. Med. Genet. 24:759-760; Nagaï et al., 1994: Am. J. Med. Genet. 49:278-280], and more recently in a Turkish family [Itin et al., 1996: Dermatology 193:349-352]. We report an additional observation in a patient of European descent, who presented with short stature, cone-shaped epiphyses, sparse hair, a pear-shaped nose, normal intelligence and severe brachydactyly. Neither parent had manifestations of TRP and there was no other reported case in the family, indicating a presumably fresh mutation. Our observation refines the clinical spectrum of TRP III in another ethnic background and may be of help in identifying the gene or genes for TRP syndromes.

Non-surgical management of achalasia.

Pneumatic dilatation of the cardia is an effective procedure to treat patients suffering from achalasia. Eighty percent of these patients can be expected to have excellent or good results for 6 years after the first dilatation. A repeat dilatation should be performed as soon as the patient has recurrent symptoms, usually every 2 years. Calcium channel blockers (nifedipine and verapamil) or nitrates (isosorbide dinitrate) decrease LES pressure but do little to the clinical symptomatology of patients with achalasia; however such drug therapy may be tried as an adjunct in patients who remain symptomatic after pneumatic dilatations or myotomy. Pneumatic dilatation and surgical myotomy both reduce LES pressure; with pneumatic dilatation, enough residual LES pressure is retained to prevent gastroesophageal reflux. Indeed, reflux esophagitis seems to occur more often after surgery than after forceful dilatations. We think that pneumatic dilatation should be performed as the primary therapy and surgery reserved for the failures of this procedure.