PubMed Health⌕ Search

Biomedical subjects

M C Babron

Publications and source records attributed to M C Babron.

At least 19 recordsLinked to original sources
PubMed1992

Failure to replicate linkage between chromosome 5q11-q13 markers and schizophrenia in 28 families.

Sherrington et al. (1988) reported linkage between markers located on the 5q11-q13 region of chromosome 5 and schizophrenia in five Icelandic and two British families. To date, however, all attempts to replicate the initial finding have failed. Using three markers of chromosome 5, we have studied 28 additional French pedigrees. When our data were analyzed both with parametric (i.e., lod scores) and nonparametric methods, we found no evidence of linkage. Thus, we were unable to replicate the earlier report by Sherrington et al.

Chromosomes, Human, Pair 5↗
PubMed1991

Thrombosis in systemic lupus erythematosus: a French collaborative study.

A retrospective study was undertaken of 120 children with systemic lupus erythematosus (SLE) seen in Paris and its immediate suburbs who fulfilled at least four of the American College of Rheumatology diagnostic criteria for SLE, and in whom the disease was diagnosed before the age of 16 and between January 1975 and December 1987. Eleven of these children (eight girls and three boys) all more than 10 years of age (mean follow up 8.1 years; range 3-13) had thrombotic episodes (9%). Thrombosis was one of the presenting signs in seven patients; in five it was associated with typical symptoms of SLE, and in the other two the thrombotic episode was isolated and diagnosis of SLE was delayed one and three years. Of a total of 16 thrombotic episodes (six of which were recurrent), 14 involved the leg veins, and in four there was associated pulmonary embolism. There were two episodes that affected cerebral arteries. The American College of Rheumatology diagnostic criteria for SLE as well as the incidence of lupus anticoagulant, positive direct Coombs test, and vasculitis in this group of patients was compared with the incidence in patients with SLE but no thrombosis. Only lupus anticoagulant was significantly associated with thrombotic episodes: eight of 11 (73%) of patients with SLE and thrombotic (arterial or venous) episodes had lupus anticoagulant compared with only 10 of 74 patients (14%) with no history of thrombotic events in the same age group.

Adolescent↗
PubMed1991

[Unfavorable outcomes in disseminated lupus erythematosus in children. Cooperative study in the Paris region].

Pediatric cases of systemic lupus erythematosus with an unfavorable outcome (terminal renal failure requiring chronic hemodialysis, or death) assembled during a retrospective multicenter study of pediatric SLE in the Paris metropolitan area were analyzed. Seven patients (6 girls, 1 boy) were entered into a chronic hemodialysis program. Four had diffuse proliferative glomerulonephritis, the pattern of glomerular disease classically responsible for end-stage renal failure. The other three patients had membranous glomerulonephritis with active segmental lesions, a form of glomerulopathy whose severe prognosis deserves to be emphasized. Nine other patients (8 girls, 1 boy) died. In six patients, death occurred as a result of a flare with malignant hypertension and progressive renal failure (1 case), pancreatitis (1 case), encephalopathy (2 cases) or cardiomyopathy (2 cases). An infectious disease (tuberculosis, mumps) was apparently the cause of the two cases of encephalopathy. One girl died as a result of a hemorrhagic syndrome with a cerebral hematoma. Two other girls died at home. Overall, among 111 children with SLE 14% had an unfavorable outcome. Sex and age at onset seemed to have no bearing on prognosis. Patients with renal involvement were apparently more likely to have an unfavorable outcome. Lastly, although the influence of ethnic origin is unproven, children living in foreign countries of French overseas territories, but treated in France have an increased risk for unfavorable outcomes.

Adolescent↗
PubMed1991

Complementation and maternal effect in insulin-dependent diabetes.

The marker association segregation chi-square (MASC) method was applied to a sample of 416 Caucasians affected with insulin-dependent diabetes mellitus (IDDM), for which information on the parental and sibship status was available, as well as HLA typing. We show that the model which best explains all the observations assumes a cis or trans complementation of two tightly linked genes within the HLA region, an additional maternal effect, and other familial factors. The HLA molecule corresponding to the complementation of Arg52(+) and Asp57(-) has been recently proposed as explaining susceptibility to IDDM. However, this hypothesis does not account for the overall observations made on the HLA marker in IDDM patients and their relatives. The MASC method may also be applied to evaluate the risk for relatives of an affected individual (the "index"). For example, the risk for a sib depends not only on the parental status and on the number of HLA haplotypes he shares with the index, but also on which haplotype the index himself inherited from his mother and father.

Diabetes Mellitus, Type 1↗
PubMed1990

Assessing the effect of multiple linkage tests in complex diseases.

The significance of a lod score value of 3 is very difficult to assess in linkage studies between a genetic marker and a complex disease. One reason is that multiple tests may have been performed, voluntarily or otherwise. For the same disease, linkage may be tested by different laboratories with several markers under various genetic models and diagnostic schemes for the disease. In such a case, we show that the probability of getting a lod score value of 3 under independent transmission of the disease and the marker may be not negligible.

Female↗
PubMed1990

Linkage study of a large family with autosomal dominant polycystic kidney disease with reduced expression. Absence of linkage to the PKD 1 locus.

We describe a large three generation family with autosomal dominant polycystic kidney disease (PKD). Ultrasonographic screening of 60 family members revealed 20 individuals, whose age ranged from ten to eighty years, with one or several cysts in only one kidney and 7 individuals with cysts in both kidneys. Transmission of unilateral cysts seems to be autosomal dominant, although there are some generation gaps. Linkage studies with several markers of the PKD1 locus on the short arm of chromosome 16 showed no linkage with the disease. Lod scores for linkage between the disease and the most informative marker 3'HVR were computed using different penetrance models and several hypotheses concerning the clinical status of individuals with unilateral renal cysts. Results varied from Z = 1.31 to Z = -21.47 (theta = 0). Smith's test of heterogeneity gave a conditional probability of non-linkage between 0.9 and 1.0. We conclude that this family presents a form of autosomal dominant PKD with reduced penetrance and no linkage to the PKD1 locus on the short arm of chromosome 16. Other hypotheses, such as the existence of two distinct hereditary diseases in this large family, or neomutation in one branch of the family associated with a high frequency of isolated renal cysts, are also considered.

Family↗
PubMed1990

Hereditary retinoblastoma: can balanced insertion entirely explain the differences of expressivity among families?

Although the retinoblastoma gene has been isolated and sequenced, the difference in penetrance and expressivity among families has not yet been fully explained. Balanced chromosomal insertion involving the 13q14 regions has been shown to account for some families with several unaffected carriers. Since there could be cases with karyotypically undetectable insertions, we tested whether this mechanism was general enough to explain the whole difference in expressivity among families. Using 166 pedigrees, reported in nine series available in the literature (including our own), we conclude that balanced insertion cannot entirely explain the familial data, even if we allow for a reduced viability of unbalanced gametes. Other mechanisms are proposed and discussed in this paper.

Chromosome Aberrations↗
PubMed1990

Sampling strategy in linkage studies of affective disorders.

Evidence of linkage in families of bipolar patients has so far been identified with genetic markers on chromosome X and 11. However, replications of these data have not consistently been reported in either case, which favours the hypothesis of genetic heterogeneity. Therefore, we have tried to outline a sampling strategy for linkage replication in affective disorders. We estimated the average number of nuclear families required to replicate X or 11 linkage as a function of the degree of heterogeneity as well as the number to prove heterogeneity given that linkage exists. The results are presented and discussed.

Bipolar Disorder↗
PubMed1990

The Gm-Pi linkage in 843 French families: effect of the alleles Pi Z and Pi S.

Linkage analysis was performed between Gm and Pi in 843 French families. The overall recombination fraction is equal to 0.25 with a sex difference ratio of 1.4 (recombination fraction of 0.20 in males and 0.29 in females), confirming previous results in the literature. Our study does not confirm the existence of a heterogeneity in recombination rate of Pi S versus non-S alleles, but it confirms the previous finding that the presence of the Pi Z allele tends to decrease the recombination rate between the two loci. This decrease appears to be similar in both sexes, and not uniquely in males as previously noted. This result suggests a possible linkage disequilibrium between the Pi Z allele and a presumably large inversion between the two loci Gm and Pi.

Alleles↗
PubMed1989

Testing genetic models for IDDM by the MASC method.

The MASC method has been applied to the GAW5 data. The method uses the simultaneous information on association and segregation of the HLA marker with the disease and the segregation of the HLA marker in affected families. It also takes into account the differential risk for parents of a patient, as well as the different HLA haplotype sharing, according to the HLA genotype of the patient. The goodness of fit of several genetic models has been tested. The observed data are not compatible with a two-allele, one-locus model, but they fit a three-allele, one-locus model and a complementation two-locus model if additional familial correlation is allowed.

Diabetes Mellitus, Type 1↗
PubMed1989

Genetic susceptibility to leprosy on a Caribbean Island: linkage analysis with five markers.

Our recent segregation analysis, carried out on 27 large pedigrees from a Caribbean island (Desirade), has shown the presence of recessive major gene(s) controlling susceptibility to leprosy per se and nonlepromatous leprosy, respectively. Linkage analysis was performed between each of these two detected genes and each of five markers typed in the Desirade population: HLA, ABO, Rhesus, Gm and Km. No positive significant lod score was observed. However, for leprosy per se close linkage was excluded with Rhesus and Gm (and also with ABO and HLA, considering a lower value for the frequency of the gene controlling susceptibility to leprosy per se). The highest lod score, although not significant, was obtained between the gene for nonlepromatous leprosy and ABO. Our overall results, joined with previous studies and experimental data, suggest that the gene controlling susceptibility to leprosy per se and that controlling susceptibility to nonlepromatous leprosy might be different, acting at successive stages of the immune response to infection with Mycobacterium leprae.

ABO Blood-Group System↗
PubMed1988

A new method to test genetic models in HLA associated diseases: the MASC method.

We propose a new method to analyse data on HLA associated diseases. The method uses the simultaneous information on the marker associations and segregation with the disease. It may also take into account the differential risk of being affected for specific relatives of a patient as well as the differential HLA haplotype sharing according to the marker genotype of the patient. It is based on the principle of minimization of a sum of independent chi-squares. It allows us to test the goodness-of-fit of various models in an easy and economical way. The method is applied to a sample of 269 French IDDM patients and their relatives leading to the rejection of models with one locus closely linked to HLA with two and three alleles.

Alleles↗
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↗