Search PubMed⌕ Search

Biomedical subjects

A Chaventre

Publications and source records attributed to A Chaventre.

16 recordsLinked to original sources
PubMed2002

Familial deafness, congenital heart defects, and posterior embryotoxon caused by cysteine substitution in the first epidermal-growth-factor-like domain of jagged 1.

In the present study, we report a kindred with hearing loss, congenital heart defects, and posterior embryotoxon, segregating as autosomal dominant traits. Six of seven available affected patients manifested mild-to-severe combined hearing loss, predominantly affecting middle frequencies. Two patients were diagnosed with vestibular pathology. All patients had congenital heart defects, including tetralogy of Fallot, ventricular septal defect, or isolated peripheral pulmonic stenosis. No individual in this family met diagnostic criteria for any previously described clinical syndrome. A candidate-gene approach was undertaken and culminated in the identification of a novel Jagged 1 (JAG1) missense mutation (C234Y) in the first cysteine of the first epidermal-growth-factor-like repeat domain of the protein. JAG1 is a cell-surface ligand in the Notch signaling pathway. Mutations in JAG1 have been identified in patients with Alagille syndrome. Our findings revealed a unique phenotype with highly penetrant deafness, posterior embryotoxon, and congenital heart defects but with variable expressivity in a large kindred, which demonstrates that mutation in JAG1 can cause hearing loss.

Abnormalities, Multiple↗
PubMed1999

[Management strategies for endemic goiter in developing countries].

Despite significant progress in the last decades, endemic goiter remains a serious public health problem in the developing world, especially in Africa. Even in countries that have successfully reduced overall incidence to acceptable levels, endemic areas often remain. This persistence is due to the inadequacy of preventive measures and poor follow-up of control programs. The main etiologic factor in endemic goiter is inadequate dietary intake of iodine. This commonly occurs in communities depending exclusively on local produce grown on iodine-poor land, especially in mountain areas. Endemic goiter is epidemiologically associated with cretinism, deaf-mutism, and mental retardation. Even mild iodine deficiency leads to clinical hypothyroidism and moderate myxoedema with significantly reduced intellectual performance. Prevention of endemic goiter depends mainly on increasing the iodine intake of people in endemic areas. When iodine intake reaches the estimated adult minimum requirement (100 to 150 micrograms per day), the prevalence of goiter decreases. Two approaches have been used to increase iodine intake. The first consists of adding iodine to food staples such as table salt. The second consists of medical treatment using agents such as iodized oil. Iodization or iodination of salt is the most widespread and cost-effective method of prevention. Administration of iodized oil has been used only in severely endemic areas and in regions where reliable provision of iodinized salt is prevented by geographical barriers or political factors. However, iodized oil has been helpful in the start-up phase of prevention programs using iodized salt, either as an emergency measure or as a mean of convincing officials of the efficacy of iodine prophylaxis.

Adult↗
PubMed1994

Hemoglobinopathies in the Dogon Country: presence of beta S, beta C, and delta A' genes.

The population of the Dogon, located in Mali, is divided in an endogamic Noble class and two endogamic servant castes (Tanners and Blacksmiths). We find that the polymorphic frequencies of beta c, beta S, and, unexpectedly, a mutation of the delta-chain (delta A'), are geographically (valley vs. plateau) as well as social status dependent.

Base Sequence↗
PubMed1994

Serogenetic analysis in the study of the population structure of the eastern Adriatic (Croatia).

The anthropogenetic structure of six island and peninsular populations (Brac, Hvar, Korcula, Peljesac, Silba, and Olib) of the eastern Adriatic, Croatia, is analyzed on the basis of the study of four different erythrocyte antigen systems or groups (ABO, Rhesus, Kell-Celano, P) and two erythrocyte isoenzyme systems (ACP, ESD). The average sample size was 555 individuals. Allele frequencies, genetic distances, and gene diversity values were computed. The results indicate that all the populations in question have preserved their separate characteristics over the course of their (micro)evolution to the present day; this is especially noticeable for the island populations of Korcula and Olib, as these are distinguished from the other four populations by a greater degree of isolation. Today's genetic structure of the six populations can be explained through the existing historical and cultural data for the region in question, which indicate that over the course of their ethnohistory they were all influenced by significant waves of immigration and selective emigrations that must have greatly shaped their present-day population structure.

Alleles↗
PubMed1994

Haemoglobinopathies C and S in the Dogons.

The distribution of haemoglobins C and S was studied in a population of caste and non caste Dogons living in villages located on the plateau and scree regions in the Sangha department of Mali. Results showed a 15.77% prevalence of haemoglobinopathy AC. Haemoglobin C was found in both plateau and scree villages and equally among caste and non caste Dogons, while the homozygous form CC was absent in non Dogons. The prevalence of haemoglobinopathy AS was extremely low with a calculated frequency of 3.05%, allele S being restricted to areas where one is likely to encounter populations other than the Dogon people. Homozygotes SS were not detected and the phenotype SC was only rarely identified. An overall analysis of these data not only suggests that allele S is of recent introduction in the Dogons but also raises the question as to whether their origin is not the voltaic rather than the Manding plateau. Studies of marriage patterns and haplotypes currently in progress should enable resolution of this controversy.

Anemia, Sickle Cell↗
PubMed1992

Factor structure of morphometric variables measured on six metacarpal bones.

Morphometry of the second, third and fourth metacarpal bone was performed on hand-wrist radiograms of both hands in a sample of 434 male and 549 female adult subjects. Morphometric data (bone length-L, total diaphysis width-T and medullary canal width-M) and age were processed using principal factor analysis with oblique rotation, separately for males and females. In both sexes three factors accounting for 74.7% of the total variance were extracted, but their patterns of variation differed. Factors-"cumulative environmental-genetic factor", "longitudinal factor", and "transversal factor"-are discussed within the context of their biological meaning affecting the phenotypic formation of metacarpal skeleton in a given population.

Adult↗
PubMed1991

Nucleotide sequence evidence of the unicentric origin of the beta C mutation in Africa.

The origin of the beta C mutation was studied by characterizing nucleotide sequence polymorphisms on beta C chromosomes of patients from various African countries. In the majority of cases, the beta C mutation was found in linkage disequilibrium with a single chromosomal structure as defined by classical RFLP haplotypes, intergenic nucleotide sequence polymorphisms immediately upstream of the beta-globin gene, and intragenic beta-globin gene polymorphisms (frameworks). In addition, three atypical variant chromosomes carrying the beta C mutation were observed, and are most probably explained either by a meiotic recombination (two cases) or by one nucleotide substitution occurring in an unstable array of tandemly repeated sequences (one case). These data demonstrate the unicentric origin of the beta C mutation in central West Africa, with subsequent mutational modification in a small number of instances. The data also supports gene flow of the beta C chromosome from subsaharan Africa to North Africa.

Africa↗
PubMed1991

[Gene mutations of cystic fibrosis in Brittany population].

Eighty percent of chromosomes from cystic fibrosis children in Brittany exhibit the major gene mutation (delta F 508) consisting in deletion of three nucleotide pairs. Eighty-seven chromosomes without the delta F 508 mutation were studied for as yet undescribed gene mutations. A large number of mutations were located in exons 10 and 11. Consequently, a global strategy for identifying mutations in these exons was developed. Analysis of pedigrees of cystic fibrosis patients in Brittany evidenced a clear founder effect. Appropriate prevention strategies will therefore be developed.

Cystic Fibrosis↗
PubMed1990

[Familial medullary thyroid cancer. Contribution of genealogy and genetics to the study of two families].

A geneological study made it possible to establish a link between two medullary thyroid carcinoma families from Normandy totalling 9 sick subjects, and a probable link with a third family. The study contributed to the diagnosis of multiple endocrine neoplasia type IIa, whereas the condition had been diagnosed for 6 years as familial medullary thyroid carcinoma, without phaechromocytoma. Group in these two families together increased the number of subjects tested, thereby facilitating genetic link analysis and enabling the link with markers of the disease on chromosome 10 to be asserted. The genetic study can now be used to detect individuals at risk, and with regular laboratory tests the diagnosis will be made at the "precancerous" stage. A genealogical study going back to the family-founding couple will increase the population which will benefit from screening in this region north of Rouen.

Adrenal Gland Neoplasms↗
PubMed1989

Screening for medullary thyroid cancer in France: a national effort. French Medullary Study Group (GETC).

Screening for medullary thyroid cancer (MTC) in France is based on a protocol that has been widely distributed nationally. A network of coordinators utilizing a common questionnaire provides for an effective national screening program. Calcitonin stimulation procedures are systematically used for all first-degree relatives of MTC patients. Pathological studies utilize special immunopathologic techniques. Genealogic information is obtained on all index cases, and blood specimens are collected for establishing permanent cell lines. The data collected are used not only to establish the diagnosis of the hereditary or sporadic form of the disease but also to expand the screening as appropriate. This common protocol has benefited patients and their families by improving early detection of cases, increasing the number of families available for follow-up, and improving the prognosis of this cancer. Studies on these families have contributed significantly to the localization of the multiple endocrine neoplasia type 2 gene.

France↗
PubMed1975

The HL-A gene structure of Twareg populations. II. The Kel Dinig.

The HL-A groups of 138 Kel Diniq Twaregs were determined by the platelet complement fixation microtechnique. Their HL-A characteristics, compared to those of Caucasoid populations, are: decrease in HL-A2, 9, W17 and W15; increase in W28, W32, HL-A7, W5, W10 and second locus blank; absence of Da25 (W30 plus W31), HL-A13, W15, W18, W27. This genetic structure is in accordance with the isolated condition of this population. The most frequent haplotypes are W28,HL-A7, common to both the Kel Diniq and the Kel Kummer Twaregs previously studied; W32,W10 and HL-A3, HL-A5, Kel Diniq only. These two populations are both isolates, with a common origin the seventeenth century, but separated as from that date. Genealogical studies have enabled the haplotype W28,HL-A7 to be attributed to the two brothers who founded the populations in the seventeenth century. A comparison of these two populations constitutes a model for the study of genetic drift and the founder effect.

Complement Fixation Tests↗