Mutation analysis in the HFE gene in patients with hereditary haemochromatosis in Saguenay-Lac-Saint-Jean (Quebec, Canada).

A mutation analysis of the HFE gene followed, when applicable, by sequencing was performed on 47 patients with hereditary haemochromatosis (HH) living in Saguenay-Lac-Saint-Jean. The C282Y and H63D mutations were present on 50% and 20.3% of the HH chromosomes respectively. These frequencies were very different from those found in other populations and could be, at least partially, the result of a founder effect. No new mutation was identified among the remaining 28.1% of the HH chromosomes. Five of the eight probands with no mutation in the HFE gene had a severe and early onset suggestive of juvenile haemochromatosis.

Clinical and molecular aspects of juvenile hemochromatosis in Saguenay-Lac-Saint-Jean (Quebec, canada).

We report the clinical, biochemical, and genetic characteristics of 13 hemochromatosis patients from Saguenay-Lac-Saint-Jean in whom the first symptoms appeared before age 30. Although the mean age at onset of the first symptoms was 21. 5 years, their mean age at diagnosis was 23.8 years; the diagnosis was particularly delayed among women. Seventy-seven percent of the patients had hypogonadotrophic hypogonadism and 69% heart failure and/or cardiac arrhythmias. Genetic analysis of the HFE gene revealed heterozygosity for the C282Y mutation in 2 patients and for the S65C mutation in 2 others and homozygosity for the H63D mutation in 1 patient. The remaining 8 patients had no identified mutation in the HFE gene, although sequencing of all seven codons and intron-exon junctions was performed (5 patients). All 13 patients fulfill the clinical criteria of juvenile hemochromatosis and represent the largest cluster thus far reported.

A comparison of RFLP maps based on anther culture derived, selfed, and hybrid progenies of Solanum chacoense.

Comparative RFLP linkage maps were constructed using five segregating populations derived from two self-incompatible lines (termed PI 230582 and PI 458314) of diploid tuber-bearing Solanum chacoense Bitt. The analysis was based on 84 RFLP loci identified by 73 different cDNA clones. Distortion of expected Mendelian segregation ratios was observed; less than 10% of the markers showed a skewed segregation in the gametes forming the F1, hybrid population compared with 30% in the selfed population and 46 and 70% in the two populations produced by anther culture. For the anther culture derived populations, most of the skewed loci were scattered throughout the genome, whereas in the populations derived from selfing, they were found primarily in linkage group 1, around the S locus. In this study, we also found that the rate of meiotic recombination could differ between the male and female gametes produced by our parental lines. Thus, male gametes of line PI 458314 showed significantly less recombination as assessed by the total length of the map (206 cM for male gametes vs. 375 cM for female gametes) and the phenomenon was genome-wide. In contrast, the maps from the gametes of PI 230582 had about the same length, but some linkage groups were longer in the female gametes, while others were longer in the male gametes. Key words : Solanum chacoense, RFLP, anther culture, skewed segregation, self-incompatibility, sex differences in recombination.

RFLP analyses and segregation of molecular markers in plants produced by in vitro anther culture, selfing, and reciprocal crosses of two lines of self-incompatible Solanum chacoense.

RFLP analyses were used to characterize several plant populations of Solanum chacoense Bitt. developed to investigate the generation of new S alleles at the self-incompatibility locus. The plant material consisted of two diploid parental lines, their anther culture derived (AC) progenies, their selfed progenies, and their reciprocal F1 hybrids. The RFLP analyses on the AC plants (121 individuals in total) permitted unambiguous identification of their origin. In particular, a distinction between plants originated from reduced (n) or unreduced (2n) microspores could be made. All the AC plants produced by gametic embryogenesis showed distinct RFLP patterns, whereas a number of clones (i.e., plants with identical RFLP patterns) were found among those regenerated via callus. The analyses conducted on the selfed progenies (69 plants) and the F1 hybrids (66 plants) showed only one case of accidental outcross. Segregation studies of the RFLP markers revealed significant deviations from expected Mendelian ratios in both AC-derived populations, as well as in the selfed progenies. Such deviations, however, were rare in the reciprocal F1 hybrids. These results are discussed in relation to the possible presence of genetic sieves operating during AC, illegitimate selfing, or during normal fertilization.

Restriction fragment length polymorphism (RFLP) analyses of plants produced by in vitro anther culture of Solanum chacoense Bitt.

In this study, a novel approach was used to characterize the genetic architecture of plants produced by in vitro anther culture of two lines of self-incompatible Solanum chacoense Bitt. (2n=2x=24). We used cytological observations to determine the ploidy level of the regenerated plants and scanned genomic DNA of the anther donor plants to identify heterozygous sequences. Restriction fragment length polymorphism (RFLP) analyses permitted the visualization of DNA variations. Several heterozygous DNA markers were found within single anther donor plants. Completely homozygous lines could be easily identified. Somatically derived plants could be separated from diploid plants produced from 2n (unreduced) microspores. Our results demonstrate first division restitution (FDR) as the mechanism operating during the production of 2n microspores in one of our S. chacoense line. Potential applications of RFLP analyses for genetic mapping, identification of lethal alleles and quantitative trait loci (QTL) with haploid or homozygous diploid plants and determination of gene-centromere distance with diploid plants derived from 2n microspores will be discussed.