Biomedical subjects

F Simard

Publications and source records attributed to F Simard.

42 records · Page 3Linked to original sources

PubMed1991

Birth distribution in cystic fibrosis in Saguenay-Lac-St-Jean, Quebec, Canada.

Although a seasonal trend in the birth distribution has been reported in cystic fibrosis (CF), this finding is still very controversial. The birth distribution of 113 patients with cystic fibrosis born in Saguenay-Lac-St-Jean (complete ascertainment) was analysed using two different statistical methods. Our results showed no monthly or seasonal birth variation. It is likely that a bias owing to incomplete ascertainment might explain why some previous studies found a seasonal trend in the birth distribution of cystic fibrosis.

Cystic Fibrosis↗

PubMedDate not supplied

Reproductive attitudes of couples having a child with cystic fibrosis in Saguenay-Lac-Saint-Jean (Quebec, Canada).

Cystic fibrosis (CF) has a high incidence (1/936 live births) and carrier rate (1/15 inhabitants) in Saguenay-Lac-Saint-Jean. One objective of a major enquiry among several subsets of individuals from this high-risk population for CF was to evaluate the reproductive behaviour of couples with a CF child attending the comprehensive CF clinic in Chicoutimi. The knowledge of the recurrence risk resulted in deciding against further progeny or in reducing the number of children. More reliable contraception methods after the birth of the CF child, but not prenatal diagnosis, were used. Although a minority of parents with a CF child would abort a CF foetus, they apparently started viewing pregnancy interruption for CF after prenatal diagnosis as an acceptable reproductive option.

Child↗

PubMedDate not supplied

Natural swarming behaviour of the molecular M form of Anopheles gambiae.

In Anopheles gambiae, as in most species of mosquitoes, mating is initiated in flight. The males aggregate in aerial swarms and conspecific females individually fly to these swarms where they mate with males. In this study, we investigated the swarming behaviour of A. gambiae and conducted 2 surveys in the rice field area of the Vallée du Kou in Burkina Faso in 1999 and 2002. A high number of anopheline mosquitoes were observed in this area and both molecular M and S forms of A. gambiae were found in sympatry. Swarms formed a few minutes after sunset in different places and no obvious markers were associated with their occurrence. However, swarms occurred close to cow herds generally in open flat areas, 2-3 m above the ground. Overall, 2829 anopheline mosquitoes were collected from 21 swarms composed primarily of males. A few specimens of Culex quinquefasciatus were collected from 3 swarms. Although both molecular M and S forms were found in sympatry in the village, swarms were composed almost exclusively of the molecular M form. This suggests that there are alternative swarming habits for both molecular M and S forms of A. gambiae in nature.

Africa, Western↗

PubMedDate not supplied

Genealogy and geographical distribution of CFTR mutations in Saguenay Lac-Saint-Jean (Quebec, Canada).

Saguenay Lac-Saint-Jean (SLSJ), a region located in northeastern Quebec, has a high incidence of cystic fibrosis (CF). During the past few years the majority of the CF patients have been genotyped. The geographical distribution of the birth places of the patients and obligate carriers of the 621 + 1G-->T, the A455E and the delta F508 mutations (which accounted for 89% of the CF chromosomes) showed differences that can be explained by some degree of isolation but also by differential migration. The mean inbreeding and kinship coefficients were higher among the various CFTR mutation groups than in the general population. An ancestor couple common to most of the A455E carriers was identified. These data further substantiate the role of founder effect in the CF population of SLSJ.

Cystic Fibrosis↗

PubMedDate not supplied

Population Structure of Anopheles gambiae in Africa.

The population structure of Anopheles gambiae in Africa was studied using 11 microsatellite loci in 16 samples from 10 countries. All loci are located outside polymorphic inversions. Heterogeneity among loci was detected and two putative outlier loci were removed from analyses aimed at capturing genome-wide patterns. Two main divisions of the gene pool were separated by high differentiation (F(ST) > 0.1). The northwestern (NW) division included populations from Senegal, Ghana, Nigeria, Cameroon, Gabon, Democratic Republic of Congo (DRC), and western Kenya. The southeastern (SE) division included populations from eastern Kenya, Tanzania, Malawi, and Zambia. Inhospitable environments for A. gambiae along the Rift Valley partly separate these divisions. Reduced genetic diversity in the SE division and results of an analysis based on private alleles support the hypothesis that a recent bottleneck, followed by colonization from the NW populations shaped this structure. In the NW division, populations possessing the M rDNA genotype appeared to form a monophyletic clade. Although genetic distance increased with geographic distance, discontinuities were suggested between certain sets of populations. The absence of heterozygotes between sympatric M and S populations in the DRC and the high differentiation in locus 678 (F(ST)>0.28) contrasted with low differentiation in all other loci (-0.02<F(ST)<0.09) and with the persistence of departures from Hardy-Weinberg expectations within each form in the DRC. Neither recent reproductive isolation alone nor selection alone can explain these results, a situation that is compatible with incipient speciation. Because it is possible that the molecular forms play different roles in malaria transmission, future studies should treat them separately.

Africa South of the Sahara↗

PubMedDate not supplied

Phenotypic variability in five cystic fibrosis patients compound heterozygous for the Y1092X mutation.

Five cystic fibrosis (CF) patients distributed in three families and compound heterozygotes for the Y1092X mutation have been followed for a period ranging from 5 to 20 years. The genealogical reconstruction identified a common ancestor couple to all 3 families at the 5th generation. All 5 patients were pancreatic insufficient. A high variability in the clinical aspects and pulmonary function was seen between the families, but not within. Based on our observations, it will be very difficult to predict the course of disease for CF patients with the Y1092X mutation, even if they are closely related (first-degree cousins).

Adolescent↗