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M Blayau

Publications and source records attributed to M Blayau.

At least 19 recordsLinked to original sources
PubMed2005

Cleft lip/palate and CDH1/E-cadherin mutations in families with hereditary diffuse gastric cancer.

We report the association of CDH1/E-cadherin mutations with cleft lip, with or without cleft palate (CLP), in two families with hereditary diffuse gastric cancer (HDGC). In each family, the CDH1 mutation was a splicing mutation generating aberrant transcripts with an in-frame deletion, removing the extracellular cadherin repeat domains involved in cell-cell adhesion. Such transcripts might encode mutant proteins with trans-dominant negative effects. We found that CDH1 is highly expressed at 4 and 5 weeks in the frontonasal prominence, and at 6 weeks in the lateral and medial nasal prominences of human embryos, and is therefore expressed during the critical stages of lip and palate development. These findings suggest that alteration of the E-cadherin pathway can contribute to human clefting.

Adult↗
PubMed2001

Holoprosencephaly due to mutations in ZIC2: alanine tract expansion mutations may be caused by parental somatic recombination.

We report on the prevalence of mutations in the zinc finger transcription factor gene, ZIC2, in a group of 509 unrelated individuals with isolated holoprosencephaly (HPE) and normal chromosomes. Overall, we encountered 16 HPE patients (from 15 unrelated families) with ZIC2 mutations. Thus, ZIC2 mutation was the apparent cause of HPE in 3-4% of cases. Seven mutations were frameshifts that were predicted to result in loss of function, further supporting the idea that ZIC2 haploinsufficiency can result in HPE. One mutation, an alanine tract expansion which is caused by the expansion of an imperfect trinucleotide repeat, occurred in seven patients from six different families. In three of those families, the father was found to be apparently mosaic for the mutation. We hypothesize that this mutation can arise through errors in somatic recombination, an extremely unusual mutation mechanism. In addition, one mutation resulted in a single amino acid change and one mutation was an in-frame deletion of 12 amino acids. The central nervous system malformations seen in patients with ZIC2 mutations ranged from alobar HPE (most common) to middle interhemispheric fusion defect (one case). Although severe facial anomalies are common in HPE, all of the patients with ZIC2 mutations had relatively normal faces, suggesting that ZIC2 mutations represent a large proportion of HPE cases without facial malformation.

Alanine↗
PubMed2001

A new mutation of E-cadherin gene in familial gastric linitis plastica cancer with extra-digestive dissemination.

Over a 12-month period, we diagnosed poorly differentiated infiltrative independent-cell gastric adenocarcinoma in two brothers and one sister aged 41 to 47 years. Their father had died from antral cancer at the age of 34 years. These cancers had two characteristic clinical features: rapid course and distant malignant dissemination. In all three patients, polymerase chain reaction-sequencing of the E-cadherin (CDH1) gene of white blood cells identified a heterozygous nonsense mutation of exon 3, producing a stop codon at position 95 (Q95X), resulting in a truncated protein. The alteration of this protein, which plays a crucial role in epithelial cell adhesion, probably explains the clinical expression in this type of familial diffuse gastric cancer.

Adult↗
PubMed2000

Spectrum of CFTR mutations in cystic fibrosis and in congenital absence of the vas deferens in France.

We have collated the results of cystic fibrosis (CF) mutation analysis conducted in 19 laboratories in France. We have analyzed 7, 420 CF alleles, demonstrating a total of 310 different mutations including 24 not reported previously, accounting for 93.56% of CF genes. The most common were F508del (67.18%; range 61-80), G542X (2.86%; range 1-6.7%), N1303K (2.10%; range 0.75-4.6%), and 1717-1G>A (1.31%; range 0-2.8%). Only 11 mutations had relative frequencies >0. 4%, 140 mutations were found on a small number of CF alleles (from 29 to two), and 154 were unique. These data show a clear geographical and/or ethnic variation in the distribution of the most common CF mutations. This spectrum of CF mutations, the largest ever reported in one country, has generated 481 different genotypes. We also investigated a cohort of 800 French men with congenital bilateral absence of the vas deferens (CBAVD) and identified a total of 137 different CFTR mutations. Screening for the most common CF defects in addition to assessment for IVS8-5T allowed us to detect two mutations in 47.63% and one in 24.63% of CBAVD patients. In a subset of 327 CBAVD men who were more extensively investigated through the scanning of coding/flanking sequences, 516 of 654 (78. 90%) alleles were identified, with 15.90% and 70.95% of patients carrying one or two mutations, respectively, and only 13.15% without any detectable CFTR abnormality. The distribution of genotypes, classified according to the expected effect of their mutations on CFTR protein, clearly differed between both populations. CF patients had two severe mutations (87.77%) or one severe and one mild/variable mutation (11.33%), whereas CBAVD men had either a severe and a mild/variable (87.89%) or two mild/variable (11.57%) mutations.

Adult↗
PubMed2000

A new mutation in the six-domain of SIX3 gene causes holoprosencephaly.

Holoprosencephaly (HPE) is a severe brain malformation which results from incomplete cleavage of the forebrain during early embryogenesis. The aetiology of HPE is very heterogeneous. Among the genetic factors, SIX3, which is considered to be the functional orthologue of Drosophila genes sine oculis (so) and optix, has been found to be mutated in the homeodomain, in some patients with HPE (HPE2 on chromosome 2p21). We report a new HPE family, presenting a wide spectrum of clinical features, ranging from cyclopia to hypotelorism, in which a mutation was found for the first time in the SIX domain of SIX3: a GG insertion creates a frameshift leading to a nonsense mutation downstream in the homeodomain region.

Chromosomes, Human, Pair 2↗
PubMed2000

Molecular screening of the CFTR gene in men with anomalies of the vas deferens: identification of three novel mutations.

Many studies have shown that congenital absence of the vas deferens (CAVD) is a genital cystic fibrosis transmembrane conductance regulator (CFTR)-mediated phenotype, with a broad spectrum of abnormalities causing male infertility. The genotype of these patients includes mutations in the CFTR gene, e.g. DeltaDeltaF508, R117H and the T5 allele; all of which are commonly found in CAVD. In this study we have screened the entirety of CFTR gene in 47 males with anomalies of the vas deferens: 37 cases of congenital bilateral absence of the vas deferens, three cases of congenital unilateral absence of the vas deferens and seven cases of obstructive azoospermia with hypoplastic vas deferens. Among the 94 chromosomes studied, 65 mutations, of which three are novel (2789+2insA, L1227S, 4428insGA), were identified. The majority of patients (63.8%) had two detectable CFTR gene mutations. Furthermore, high frequencies of the DeltaDeltaF508 mutation (44.7%), the T5 allele (36.2%) and R117H mutation (19.1%) were observed.

Adult↗
PubMed1999

Identification of a D579G homozygote cystic fibrosis patient with pancreatic sufficiency and minor lung involvement. Mutations in brief no. 221. Online.

Here we describe the identification of an italian patient homozygote for the D579G mutation affected by a mild form of Cystic Fibrosis with pancreatic sufficiency, minor lung involvement and marked viscosity of the cervical mucous. The D579G mutation causes an A1868G transition, a substitution of an aspartic acid to a glycine residue, generating an important amino acid change (charged to hydrophobic) in the nucleotide-binding domain (NBD). The mutation was first described by Brancolini et al. (1995) on two pancreatic sufficient CF patients, compound heterozygotes for delta508F. Patients were from Southern Italy (Puglia) as the D579G homozygote one, who is a 30 years old woman from Taranto (Puglia), daughter of second cousins born in Bari (Puglia). The identification of a homozygote D579G patient might confirm that this mutation does correlate with pancreatic sufficiency and a mild pulmonary phenotype.

Adult↗
PubMed1999

Expression of the Sonic hedgehog (SHH ) gene during early human development and phenotypic expression of new mutations causing holoprosencephaly.

Holoprosencephaly (HPE), the most common developmental defect of the forebrain and the face, is genetically heterogeneous. One of the genes involved, Sonic hedgehog ( SHH ), on 7q36, has been identified as the first HPE-causing gene both in mouse and humans. In order to delineate the phenotype of specific SHH mutations, we described the expression of the SHH gene during early human embryogenesis and investigated the phenotype of novel SHH mutations. In situ hybridization studies were performed on paraffin-embedded human embryo sections at three different development stages. These studies show that SHH is expressed in the notochord, the floorplate, the brain, the zone of polarizing activity and the gut. We also report on the phenotype of four novel mutations identified in 40 HPE families (two in isolated HPE and two in familial HPE). Expressivity ranged from alobar HPE to microcephaly and hypoplasia of the pituitary gland in one family, and from HPE to an asymptomatic form in another family. No SHH mutation was found in six polymalformed cases combining HPE with other defects, such as skeletal, limb, cardiac, anal and/or renal anomalies. This study confirms the genetic heterogeneity of HPE, and further demonstrates that SHH mutations are associated with a broad spectrum of cerebral midline defects.

Brain↗
PubMed1995

Obstructive azoospermia with agenesis of vas deferens or with bronchiectasia (Young's syndrome): a genetic approach.

Two groups of infertile men with obstructive azoospermia were screened for cystic fibrosis (CF) gene mutations (delta F508, exons 3, 4, 7, 10, 11, 14a, 17b, 19, 20, 21). The first group was composed of 26 patients with congenital agenesis of vas deferens (CAVD). The second group was composed of 12 patients with obstructive azoospermia associated with chronic suppurating respiratory disease (Young's syndrome). Of the group with CAVD, 77% of patients showed at least one mutation in the CF transmembrane conductance regulator (CFTR) gene. The delta F508 mutation occurred most frequently (54%), and the second most frequent mutation to occur was R117H (27%). Six patients were double heterozygotes. In Young's syndrome, no CF mutations were detected. CAVD can be considered as an incomplete clinical form of CF. However, the differences observed in CF mutations between CF and CAVD suggest that they are different disorders resulting from mutations in the same gene. Young's syndrome is a very different clinical entity.

Adult↗
PubMed1995

Structural analysis of CFTR gene in congenital bilateral absence of vas deferens.

Congenital bilateral absence of the vas deferens (CBAVD) is found in most males with cystic fibrosis (CF), but this malformation can be observed without any pulmonary or digestive features. We have analyzed 13 exons of the CF gene in a cohort of 25 CBAVD patients. Among the 50 chromosomes studied, 24 mutations were identified: delta F508 (14 cases), R117H (7 cases), R1070W (2 cases), 621 + 1 G --> T (1 case), and A1067V (1 case). Except for delta F508, the most frequent mutations (R117H, R1070W) were not observed in the CF group (109 patients) studied in our laboratory. We discuss the significance of these results.

Adult↗