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Biomedical subjects

G Le Gac

Publications and source records attributed to G Le Gac.

7 recordsLinked to original sources
PubMed2004

Early onset hereditary hemochromatosis resulting from a novel TFR2 gene nonsense mutation (R105X) in two siblings of north French descent.

The molecular basis of hereditary hemochromatosis (HH) is more complex than previously expected. More than 80% of hemochromatosis probands of Northern European descent are homozygous for the C282Y HFE gene mutation. However, five novel non-related-HFE HH forms have now been identified. The transferrin receptor(TFR2)-linked form is inherited in an autosomal recessive pattern and is considered to be an adult-onset syndrome. Until now, it has been associated with five mutations that have only been detected in Japanese and southern European patients. Here, we report the identification of a novel TFR2 nonsense mutation in two related French adolescents. We discuss the phenotype of this sibling pair from precedent biological and clinical findings as well as the expected role of TFR2 in iron homeostasis. Finally, we suggest that iron overload phenotypes associated with mutations in TFR2 may be intermediate between those related to mutations in HFE and those related to mutations in juvenile hemochromatosis genes.

Adolescent↗
PubMed2001

Complete scanning of the hereditary hemochromatosis gene (HFE) by use of denaturing HPLC.

BACKGROUND: Between 4% and 35% of hereditary hemochromatosis (HC) probands are C282Y or H63D heterozygotes or lack both of these two common HFE mutations, and 15 novel HFE mutations have been described recently. We evaluated denaturing HPLC (DHPLC) for screening of the whole HFE coding region and further defined whether HC probands with an incomplete HFE genotype carry uncommon mutations. METHODS: Analytical conditions for each coding exon were determined by a combination of computer melting profile predictions and experimental melting curves. To test accuracy for scanning the complete HFE coding region and optimize DHPLC running conditions, each melting domain was investigated with at least one mutation or one polymorphism as reference. We tested 100 DNA samples harboring the C282Y, H63D, or S65C mutations and 17 artificially created positive controls that carried either 1 of the 14 other known HFE mutations or 3 selected polymorphisms. RESULTS: Investigations on each of the coding exons 1, 2, 4, 5, and 6 could be performed at one analysis temperature. Coding exon 3 displayed a more complex melting profile and required two analysis temperatures. DHPLC detected all known HFE mutations as well as the three selected polymorphisms. CONCLUSIONS: DHPLC can be used to scan the HFE gene in HC probands in whom at least one chromosome lacks an assigned mutation.

Chromatography, High Pressure Liquid↗
PubMed2000

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.

Adolescent↗
PubMed2000

Nramp2 analysis in hemochromatosis probands.

The mechanism that leads to iron overload in hereditary hemochromatosis is not yet fully understood and genes other than HFE may be involved. Nramp2 is an intestinal iron transporter, upregulated by dietary iron deficiency, which also colocalizes with transferrin in recycling endosomes. The purpose of the present study was to analyze the coding region of the Nramp2 gene in 14 hemochromatosis probands which did not carry any HFE mutations on both chromosomes. We confirmed the existence of a polymorphism (1254 T --> C), which presumably is not associated with hereditary hemochromatosis, but we did not find any mutation. On the other hand, we identified 17 splice variants of the Nramp2 mRNA. Eight corresponded to activation of cryptic splicing sequences between exons 3 and 4. They were observed in a majority of hemochromatosis probands and control subjects. This indicates the existence of an important splicing instability in this region. At this stage, the biological significance of these variants is unclear. Our study did not find evidence for the involvement of the Nramp2 gene in hereditary hemochromatosis. The remaining question is whether hemochromatosis probands in our study have iron overload because of environmental factors or due to mutation in gene(s) other than HFE and Nramp2.

Alternative Splicing↗
PubMed2000

Relation between HFE mutations and mild iron-overload expression.

The identification of the HFE gene involved in hemochromatosis allows genetic tests based on mutation analysis to be performed. However, discrepancies in the correlation between HFE genotypes and iron-loading status have arisen. We investigated 708 patients with various signs or symptoms suggesting a putative iron overload that, nevertheless, did not reach the current criteria for hemochromatosis diagnosis. Most of the patients (91.4%) included in our study displayed one of three classical iron marker values above the threshold defined for iron overloading. HFE mutation analysis allowed us to identify 45.7% of carrier chromosomes in the studied group of patients that showed higher frequencies of HFE mutations compared with controls. In addition, the frequencies of compound C282Y/H63D heterozygous, H63D/H63D homozygous, and C282Y heterozygous genotypes were higher than those in HH probands and controls; they accounted for 16, 5.6, and 22.5% of the patients, respectively. All genotypic groups had a significantly higher value of serum ferritin concentration compared to the normal value; only the C282Y homozygotes and compound heterozygotes with H63D had a transferrin saturation significantly higher than the normal value. On the whole the H63D homozygous and compound heterozygous patients constitute an intermediate phenotypic group between HH and controls. Some of them may reach the critical overloading defined for HH diagnosis along with a potential risk of developing complications, whereas others only show a partial phenotypic expression.

Adult↗
PubMed2000

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.

Alleles↗