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Biomedical subjects

M C Babron

Publications and source records attributed to M C Babron.

61 records · Page 4Linked to original sources
PubMed1987

Power and robustness of the linkage homogeneity test in genetic analysis of common disorders.

The power and robustness of the admixture test are studied. The power of the test depends on the genetic parameters at the disease locus. In particular, the power decreases drastically with the level of penetrance. The test is robust to errors in genetic parameters provided that the recombination fraction is not fixed a priori. However, misspecifying genetic parameters leads to a bias in the estimates of both the recombination fraction and the proportion of linked families.

Chromosome Mapping↗
PubMed1987

Studies on an isolated West Indies population (V): Genetic differentiation, evidence for founder effect and drift.

Red cell antigens [A,B,H,C,c,C(w),D,E,e,M,N,S,s,P1,K,FY(a),JK(a)] and 20 serum proteins or erythrocyte enzymes were tested in a white isolate of the French West Indies (the island of St-Barthélémy). The genetic differentiation mainly due to genetic drift and founder effect between France and this isolate and between the Leeward (parish of Gustavia) and Windward (parish of Lorient) areas within the island is discussed. Genetic admixture with black populations of African origin is very low.

ABO Blood-Group System↗
PubMed1984

HLA-associated diseases: a new method for performing linkage analysis with other markers than HLA.

It has been shown that genetic factors within the HLA region are involved in the etiology of several diseases. For some of these, the existence of another genetic factor has been suggested, although not proven. A possible way to give evidence for another locus (G) is to show that the disease and an unlinked HLA-marker locus (M) do not segregate independently. The usual lod-score method, which assumes monogenic inheritance, is inappropriate for this test. We propose a correction of this method for performing a linkage analysis between the G and M loci, taking into account the role of HLA. A very simple way of using the HLA information is by modifying, for each individual of a pedigree, the penetrance values at the G locus according to the number of HLA haplotypes shared with the index case. These penetrance values are inferred from the observed IBD (identity-by-descent) distribution of HLA haplotypes in a sample of affected sib-pairs. The advantage of using this empirical distribution is that it is not based on any assumptions concerning the mode of inheritance at the HLA-linked locus. This correction method was established using a two-locus model with restrictive assumptions. Its value is discussed for various sets of parameters in more general and realistic two-locus models using simulations.

Chromosome Mapping↗
PubMedDate not supplied

Genetics of celiac disease.

Celiac disease (CD) is a chronic inflammatory disease of the gut resulting from ingestion of gluten, occurring in genetically susceptible individuals. The strong genetic association of CD with the DQ2 and DQ8 HLA heterodimers has been known for long, but others non-HLA genes are involved. In order to identify susceptibility genes to CD, several studies have been performed, based on either linkage analyses or candidate gene approaches. This review describes these different studies and their results. The hypothesis of the implication of the DR53 heterodimer in the HLA region has been proposed. The existence of a susceptibility locus on chromosome 5q has been evidenced through linkage analysis and candidate gene strategies have revealed the role of CTLA-4 and of the immunoglobulin gamma genes in the disease.

Celiac Disease↗
PubMedDate not supplied

Polymorphism and genetic evolution in an isolate in the Antilles: Saint-Barthélémy.

St Barthélémy, a small island near Guadaloupe, has been isolated since the eighteenth century. The population is made up of two geographical isolates, genetically separated. In each, the inbreeding level is increasing on account of random genetic drift, which is reinforced by village endogamy, equivalent to a kind of spouse selection. Consanguinity between spouses has been analysed to give an estimate of the contributions of random genetic drift and spouse choice to total inbreeding. A second estimate to inbreeding can be obtained from the variation in observed gene frequencies. The two estimates obtained are of the same order, 0.6-1.0%, and are comparable with those still observed in isolated villages of the French Pyrenees.

Alleles↗