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Biomedical subjects

A Munnich

Publications and source records attributed to A Munnich.

At least 325 records · Page 18Linked to original sources
PubMed1996

Increased paternal age in CHARGE association.

The acronym CHARGE refers to a non-random clustering of congenital malformations whose cause remains unknown. Here, we report on a series of 41 patients and find a significant increase in mean paternal age of birth of CHARGE patients (33.7 +/- 8 years) compared with the control population (30.8 +/- 5 years). In contrast, maternal age was not statistically different in patients and controls. These data suggest the possible role of a dominant mutation or, less likely, a subtle chromosomal abnormality in CHARGE association.

Abnormalities, Multiple↗
PubMed1996

Common mutations in the gene encoding fibroblast growth factor receptor 3 account for achondroplasia, hypochondroplasia and thanatophoric dysplasia.

The mapping of the achondroplasia locus to the short arm of chromosome 4 and the subsequent identification of a recurrent missense mutation (Gly380Arg) in the gene encoding fibroblast growth factor receptor 3 (FGFR-3) has been followed by the detection of common FGFR-3 mutations in two clinically related disorders: thanatophoric dysplasia (TD; types I and II) and hypochondroplasia. The relative clinical homogeneity of achondroplasia was substantiated by demonstration of its genetic homogeneity: 100% of patients examined exhibited mutations in the transmembrane domain of FGFR-3. Although most cases of hypochondroplasia were accounted for by a recurrent missense substitution (Asn540Lys) in the first tyrosine kinase domain of FGFR-3, a significant proportion (40%) of the patients in the present study did not possess this Asn540Lys mutation. Furthermore, in three families with hypochondroplasia, the genetic defect was not linked to the FGFR-3 locus, thus supporting the clinical heterogeneity of this disease. In TD, a recurrent mutation located in the second tyrosine kinase domain of FGFR-3 has been detected in all TDII patients. By contrast, seven distinct mutations in three different protein domains were identified in 25 out of 26 TDI patients in this study. This suggests that TD, like achondroplasia, is a genetically homogeneous skeletal disorder.

Achondroplasia↗
PubMed1996

Evidence for a fourth locus in Usher syndrome type I.

Usher syndrome type I (US1) is an autosomal recessive condition in which three different genes have been already localised (USH1A, USH1B, and USH1C on chromosomes 14q32, 11q13, and 11p15 respectively). The genetic heterogeneity of US1 has been confirmed in a previous study by linkage analysis of 20 French pedigrees. Here, we report the genetic exclusion of the three previously reported loci in two large multiplex families of Moroccan and Pakistani origin, suggesting the existence of at least a fourth locus in Usher syndrome type I.

Abnormalities, Multiple↗
PubMed1996

Refined mapping of a gene for split hand-split foot malformation (SHFM3) on chromosome 10q25.

Split hand-split foot malformation (SHFM) is a genetically heterogeneous limb developmental defect characterised by the absence of digital rays and syndactyly of the remaining digits. Three disease loci have recently been mapped to chromosomes 7q21 (SHFM1), Xq26 (SHFM2), and 10q25 respectively (SHFM3). We report the mapping of SHFM3 to chromosome 10q25 in two large SHFM families of French ancestry (Zmax for the combined families = 6.62 at theta = 0 for marker AFM249wc5 at locus D10S222). Two recombinant events reduced the critical region to a 9 cM interval (D10S1709-D10S1663) encompassing several candidate genes including a paired box gene PAX2 (Zmax = 5.35 at theta = 0). The fibroblast growth factor 8 (FGF 8), the retinol binding protein (RBP4), the zinc finger protein (ZNF32), and the homeobox genes HMX2 and HOX11 are also good candidates by both their position and their function.

Chromosome Mapping↗
PubMed1996

Large scale deletions of the 5q13 region are specific to Werdnig-Hoffmann disease.

Spinal muscular atrophy (SMA) is characterised by degeneration of anterior horn cells of the spinal cord and represents the second most common, lethal, autosomal recessive disorder after cystic fibrosis. Based on the criteria of the Internatinal SMA Consortium, childhood SMAs are classified into type I (Werdnig-Hoffmann disease), type II (intermediate form), and type III (Kugelberg-Welander disease). Recently, two genes have been found to be associated with SMA. The survival motor neurone gene (SMN) is an SMA determining gene as it is absent in 98.6% of patients. A second gene, XS2G3, or the highly homologous neuronal apoptosis inhibitory protein gene (NAIP) have been found to be more frequently deleted in type I than in the milder forms (types II and III). We investigated the correlation between the clinical phenotype and the genotype at this loci. A total of 106 patients were classified into type I (44), type II (31), and type III (31) and analysed using SMN, markers C212 and C272, and NAIP mapping upstream and downstream from SMN respectively. The combined analysis of all markers showed a large proportion of type I patients (43%) carried deletions of both SMN and its flanking markers (C212/272) and NAIP exon 5), as compared with none of the patients with type II or III SMA. The presence of large scale deletions involving these loci is specific to Werdnig-Hoffman disease (type I) and allows one to predict the severity of the disease in our series.

Adult↗
PubMed1996

Clinical and genetic heterogeneity of hypochondroplasia.

Hypochondroplasia (HCH) is an autosomal dominant condition characterised by short stature, micromelia, and lumbar lordosis. In a series of 29 HCH probands (13 sporadic cases, 16 familial cases), we tested their DNA for the N540K recurrent mutation previously described in the proximal tyrosine kinase domain of the FGFR3 gene on chromosome 4p16.3, and we detected this mutation in 21/29 HCH patients. Interestingly, three familial cases were clearly unlinked to chromosome 4p16.3. Reviewing the clinical and radiological manifestations of the disease a posteriori, we observed that the N540K mutation was associated with relative macrocrania with a high and large forehead and short hands. By contrast, in the three pedigrees inconsistent with linkage to chromosome 4p16.3, the clinical phenotype was milder, macrocephaly and shortening of the long bones was less obvious, the hands were normal, and no metaphyseal flaring was noted. This study supports the view that HCH is a clinically and genetically heterogeneous condition.

Achondroplasia↗
PubMed1996

Mutations of the fibroblast growth factor receptor-3 gene in achondroplasia.

Achondroplasia (ACH), the most common cause of chondrodysplasia in man (1 in 15,000 live births), is an autosomal dominant condition of unknown origin characterized by short-limbed dwarfism and macrocephaly. Recently, a gene for ACH has been mapped to chromosome 4p16.3. The genetic interval encompassing the disease gene contains a member of the fibroblast growth factor receptor (FGFR) family which is expressed in articular chondrocytes (FGFR3). We report here recurrent missense mutations, in a CpG doublet of the transmembrane domain of the FGFR3 protein (G380R) in 17 sporadic cases and 6 unrelated familial forms of ACH and show that the mutant genotype segregates with the disease in these families. Thus, it appears that recurrent mutations of a single amino acid in the transmembrane domain of the FGFR3 protein account for all cases (23/23) of achondroplasia in our series.

Achondroplasia↗
PubMed1996

C618R mutation in exon 10 of the RET proto-oncogene in a kindred with multiple endocrine neoplasia type 2A and Hirschsprung's disease.

The cosegregation of multiple endocrine neoplasia (MEN) type 2A with Hirschsprung's disease (HSCR), two diseases associated with mutation of the RET proto-oncogene, is infrequent. A 30-yr-old man was referred for screening of MEN 2A. Surgery for HSCR was performed at 4 yr of age. Basal and pentagastrin-stimulated calcitonin levels were abnormal. Histological examination of the thyroid confirmed bilateral medullary thyroid carcinoma. Screening of family members revealed six subjects with medullary thyroid carcinoma or abnormal pentagastrin-stimulated calcitonin test; one had an unilateral pheochromocytoma and two were affected with HSCR. DNA sequence analysis showed a heterozygote C618R mutation in exon 10 of the RET proto-oncogene in the proband and his mother, as well as in second-degree relatives with MEN 2A phenotype or HSCR. In this study, we report on a novel kindred with MEN 2A and HSCR phenotype associated with a point mutation (C618R) in one of the cysteine codons at the extracellular domain of the RET proto-oncogene.

Adult↗
PubMed1996

[Rapid demonstration of mutations previously identified in parents at risk of patients with autosomic dominant retinitis pigmentosa].

PURPOSE: We have previously identified rhodopsin gene mutations in France in autosomal dominant (ADRP) retinitis pigmentosa in France, using a combination of SSCP (single-strand conformation polymorphism) and direct sequence analysis. The aim of this study was to perform a more rapid tool to identify a mutation in a ADRP family, when this mutation has been identified for one affected member of this family. METHODS: We looked for a restriction site, created or abolished by a mutation in the rhodopsin gene. We performed in vitro DNA amplification using PCR (polymerase chain reaction), enzymatic digestion, and migration on agarose gel. RESULTS: Abnormal patterns of migration were observed for affected ADRP members. DISCUSSION: This technique is useful and rapid (less than 5 hours) to recognize a previously identified mutation. However, previous precise identification of the mutation in one member of the family is needed.

DNA Restriction Enzymes↗
PubMed1996

Mitochondrial diabetes mellitus.

In the last few years, several mitochondrial DNA mutations and deletions have been described in association with various human diseases. Mitochondrial disorders, though long regarded strictly as neuromuscular diseases, may in fact involve non-neuromuscular symptoms. Diabetes mellitus has been reported in patients presenting with large mtDNA rearrangements (deletion, deletion-duplication) or in association with mtDNA point mutations, generally in tRNA genes (tRNA(Leu(UUR)). Genetic studies have shown that these disorders occur in sporadic cases or can be maternally inherited. The main clinical feature of mitochondrial diabetes is its nearly-consistent association with other symptoms (deafness, neurologic disorders, cardiac failure, renal failure, etc.). This paper provides a review of different types of mtDNA abnormalities associated with diabetes and a study of the prevalence of mitochondrial diabetes mellitus.

Anemia, Sideroblastic↗
PubMed1996

A translocation at 12q2 refines the interval containing the Holt-Oram syndrome 1 gene.

A gene for Holt-Oram syndrome (HOS) has been previously mapped to chromosome 12q2 and designated HOS1. We have identified a HOS patient with a de novo chromosomal rearrangement involving 12q. Detailed cytogenetic analysis of this case reveals three breaks on 12q, and two of these are within the HOS1 interval. By using a combination of chromosome painting and FISH with YACs and cosmids, it has been possible to map these breakpoints within the critical HOS1 interval and thus provide a focus for HOS gene-identification efforts.

Arm↗
PubMed1996

[Genetics of Hirschsprung disease].

Hirschsprung's disease (HD) is one of the commonest gastrointestinal malformations, as it affects one child out of 5,000 births. It classically induces severe neonatal intestinal obstruction requiring surgical treatment which currently ensures a favourable prognosis for most of the affected children. Although the great majority of cases are sporadic, the existence of familial forms (10% of cases) has allowed localization and then identification of an autosomal dominant gene on chromosome 10, the RET proto-oncogene, responsible for 50% of familial forms and 15% of sporadic cases. A second gene has been recently localized on chromosome 13, the endothelium beta receptor (EDNRB) gene. Two homozygous mutations of the EDNRB gene have been identified in two consanguineous families, in which HD is associated with Waardenburg's syndrome (WS). Other heterozygous mutations have been identified in patients presenting with isolated HD and an 5% of cases of HD can be considered to present mutations of this gene. Finally, the authors have recently identified a mutation of the endothelium gene 3 (EDN3), one of the EDNRB ligands in a patient presenting with a combination of HD and WS. This mutation, present at the homozygous state in this patient, is predictive of complete absence of EDN3 protein: this is therefore the third known gene responsible for HD.

Drosophila Proteins↗
PubMed1996

[Genetics of Hirschsprung disease].

Hirschsprung disease (HD) is one of the commonest gastro-intestinal malformations, as it affects one child out of 5,000 births. It classically induces severe neonatal intestinal obstruction requiring surgical treatment which currently ensures a favourable prognosis for most of the affected children. Although the great majority of cases are sporadic, the existence of familial forms (10% of cases) has allowed the localization and then the identification of an autosomal dominant gene on chromosome 10, the RET proto-oncogene, responsible for 50% of familial forms and 15% of sporadic cases. A second gene has been recently localized on chromosome 13, the endothelin beta receptor (EDNRB) gene. Two homozygous mutations have been identified in two consanguineous families, in which HD is associated with Waardenburg syndrome (WS). Other heterozygous mutations have been identified in patients presenting with isolated HD and 5% of cases can be considered to present mutations of this gene. Finally the authors have recently identified a mutation of the endothelin 3 gene (EDN3), one of EDNRB ligands in a patient presenting a combination of HD and WS. This mutation, present at the homozygous state in this patient, is predictive of complete absence of EDN3 protein: this is therefore the third known gene responsible for HD.

Endothelin-3↗
PubMed1995

Sternal cleft: case report and review of a series of nine patients.

Cleft sternum is a rare malformation due to partial or total failure of sternal fusion at an early stage of embryonic development. Sternal clefts can be classified as superior, inferior, or complete. Here we report on a 2-year-old boy with inferior sternal cleft and complex cardiac malformation. We review a series of 9 children with sternal clefts, referred to us over a 10-year period. Hypothetical mechanisms for this developmental anomaly are discussed.

Abnormalities, Multiple↗
PubMed1995

An improved spectrophotometric assay of pyruvate dehydrogenase in lactate dehydrogenase contaminated mitochondrial preparations from human skeletal muscle.

In mitochondria-enriched preparations of human skeletal muscle, the measurement of pyruvate dehydrogenase activity, as determined by conventional spectrophotometric assay of NADH accumulation, is underestimated due to the oxidizing activity of the contaminating lactate dehydrogenase. Using a model reaction system consisting of varying mixtures of purified lactate and pyruvate dehydrogenases, we found that the presence of oxamate, a competitive inhibitor of the lactate dehydrogenase, allowed the measurement of a linear rate of pyruvate dehydrogenase activity without interference from lactate dehydrogenase. In the presence of 25 mM oxamate, this holds true up to a ratio of 30:1 for lactate to pyruvate dehydrogenases, respectively. A similar result was obtained when using human skeletal muscle mitochondria contaminated by lactate dehydrogenase. Rates of pyruvate dehydrogenase activity ranging from 50 to 120 nmol/min/mg protein could be routinely measured in such mitochondrial fractions. We concluded that the use of oxamate allows a spectrophotometric assay for pyruvate dehydrogenase activity to be utilized when screening for pyruvate dehydrogenase deficiency in mitochondria-enriched preparations of human skeletal muscle.

Animals↗