Y-chromosome DNA haplotypes in north African populations.

The frequency distribution of Y-chromosome haplotypes at DNA polymorphism p49/TaqI was studied in a sample of 505 North Africans from Mauritania, Morocco, Algeria, Tunisia, Libya, and Egypt. A particularly high frequency (55.0%) of Y-haplotype 5 (A2, C0, D0, F1, I1) was observed in these populations, with a relative predominance in those of Berber origin. Examination of the relative frequencies of other haplotypes in these populations, mainly haplotype 4 (the "African" haplotype), haplotype 15 (the "European" haplotype), and haplotypes 7 and 8 (the "Near-East" haplotypes), permit useful comparisons with neighboring peoples living in sub-Saharan Africa, Europe, and the Near East.

Trinucleotide GAA repeat expansions in seven French Friedreich ataxia families.

We collected 7 Friedreich ataxia (FRDA) pedigrees from France. All cases but one family were homozygous for an unstable GAA trinucleotide expansion in the first intron of the frataxin gene. In this peculiar pedigree absence of the GAA expansion supports the notion of possible genetic heterogeneity of FRDA.

Haplotype VIII of the Y chromosome is the ancestral haplotype in Jews.

DNA samples from Ashkenazic and Sephardic Jews were studied with the Y-chromosome-specific DNA probes p49f and p49a to screen for restriction fragment length polymorphisms and haplotypes. Two haplotypes (VII and VIII) are the most widespread, representing about 50% of the total number of haplotypes in Jews. The major haplotype in Oriental Jews is haplotype VIII (85.1%); haplotype VIII is also the major haplotype in the Djerban Jews (77.5%) (Djerban Jews represent probably one of the oldest Jewish communities). Together these results confirm that haplotype VIII is the ancestral haplotype in Jews.

Molecular characterization of Charcot-Marie-Tooth patients in 15 pedigrees from France.

Molecular characterization of Charcot-Marie-Tooth patients in 15 pedigree from France: We collected 15 Charcot-Marie-Tooth (CMT) pedigrees from France. DNA polymorphisms analysis by Southern blotting with probes at the D17S122 locus demonstrated 17p duplication in three CMT1a families and in one sporadic case. Two families affected by CMT2 showed no evidence of the duplication.

Association of apolipoprotein E allele epsilon 4 with late-onset sporadic Alzheimer's disease.

Apolipoprotein E, type epsilon 4 allele (ApoE epsilon 4), is associated with late-onset sporadic Alzheimer's disease (AD) in French patients. The association is highly significant (0.45 AD versus 0.12 controls for epsilon 4 allele frequencies). These data support the involvement of ApoE epsilon 4 allele as a very important risk factor for the clinical expression of AD.

Prenatal diagnosis for the unstable CTG repeat sequence in myotonic dystrophy: a retrospective study in a French family.

The results of DNA analysis for the unstable CTG repeat are reported in a french family of myotonic dystrophy. This retrospective study confirms results obtained previously with a linked DNA marker, using the CTG repeat DNA sequence in the same family. The demonstrated possibility of predicting phenotype as well as genotype in prenatal diagnosis is important for such a disorder, were subjects may be severely affected.

A multiple primer pairs polymerase chain reaction for the detection of human genital papillomavirus types.

We describe a polymerase chain reaction (PCR) based on the simultaneous detection of multiple strains of papillomavirus in a single reaction tube. This PCR method was specific and sensitive. We have validated this multiplex procedure on a collection of typed cervical biopsies specimens, and applied it to the detection of viruses in some clinical samples.

Prenatal diagnosis of hereditary amyloidosis in a Portuguese family living in France.

Portuguese type amyloidosis is an autosomal dominant condition caused by a mutation in the transthyretin gene. This mutation can be detected directly by the presence of a restriction site for NsiI. We report here our first prenatal diagnosis for this condition performed by chorionic villus sampling, polymerase chain reaction, and restriction enzyme digestion.

[Presymptomatic diagnosis in Huntington chorea families using the gene amplification technique]. / Diagnostic présymptomatique dans les familles de chorée de Huntington par utilisation de la technique d'amplification génique.

The presymptomatic diagnosis of Huntington chorea (HC) by genic amplification (PCR: polymerase chain reaction) of a DNA G8 sequence containing a polymorphic HindIII site was tested in a particular HC genealogy. The advantage of this method are discussed.

[Use of polymorphous DNA probes in the study of French families with Huntington's chorea]. / Utilisation des sondes polymorphes A.D.N. dans l'étude des familles françaises de chorée de Huntington.

Huntington disease (HD) is a neurodegenerative disorder caused by an autosomal dominantly inherited defect. The discovery of DNA polymorphisms genetically linked to the HD locus provided the possibility of an early presymptomatic test. The first marker locus described (G-8) had an approximately 5% recombination rate with the HD locus, and the subsequent discovery of some more tightly linked marker loci, notably D 495, has greatly improved the accuracy of presymptomatic testing. We describe here the preliminary results obtained and the difficulties encountered in a French predictive testing program on presymptomatic subjects belonging to choreic families.

Linkage analysis of French families with facioscapulohumeral muscular dystrophy.

Linkage analysis was undertaken in seven French families with facioscapulohumeral muscular dystrophy (FSHD). Six polymorphic DNA probes were studied, including random DNA sequences, coding sequences, and a hypervariable marker. No evidence for linkage of these probes to the disease was detected, and the results exclude probable location of the FSHD gene from three chromosomal regions (16p, proximal 19q, and 21q).

[Use of the polymorphism of flanking DNA probes with respect to the Xq-27 region in a great fragile X pedigree]. / Utilisation du polymorphisme des sondes flanquantes par rapport au site Xq-27 dans une grande généalogie X-fragile.

We analyzed the segregation between fragile site Xq 27 and flanking polymorphic probes (52A, for factor 9, 4D-8, for factor 8, St14 and MN12) in a great Xq-fra pedigree. On the basis of these data, the use of these probes is discussed in view of its value as a diagnostic tool.

[Techniques of DNA polymorphisms revealed by probes for the Y chromosome applied to questions of father-son line in analyses of paternity]. / Les techniques de polymorphismes de l'A.D.N. de sondes du chromosome Y appliquées au problème de filiations père-fils dans les analyses de paternité.

The Y specific probe (two 49f and 49a sub-clones) is a polymorphic one for the A (5 alleles), C (2 alleles), D (3 alleles), F (2 alleles) and I (2 alleles). We show that the corresponding allelic combinations, or haplotypes, are transmitted father-to-son in eleven random chosen families. Utilisation of these polymorphisms in other eleven father-son paternitity cases, studied for a panel of erythrocytic and seric markers, shows a good correlation between the two approaches, most of the paternies excluded by the Y probes being also excluded with other allotypic markers. Utilisation of this sort of polymorphism does not necessitate the knowledge of maternal genotype in families studied.

Familial adrenoleukodystrophy: long chain fatty acid levels and analysis with a factor VIII DNA probe.

Segregation studies of X-linked adrenoleukodystrophy (ALD) and a cloned desoxyribonucleic fragment (factor VIII gene), which detects polymorphism in the distal end of the long arm of the X chromosome (Xq28), are reported in a large sibship ALD family. The findings should permit better identification of carriers and add a new marker for identifying the ALD gene itself.