RESUMO
A refined genetic map of the spinocerebellar ataxia 2 locus was constructed through linkage and haplotype analysis of 11 large pedigrees from the Holguín SCA2 family collective. Three-point analysis makes a localization of the SCA2 mutation in the 6-cM interval D12S84-D12S79 likely. This is consistent with haplotype results indicating a crossover event between two branches of the SCA2 family Rs and placing the mutation on the telomeric side of D12S84. The microsatellite D12S105 within this interval shows a peak two-point lod score of Z = 16.14 at theta = 0.00 recombination and complete linkage disequilibrium among affected individuals. These data together with the observation of a common disease haplotype among all family ancestors support the notion of an SCA2 founder effect in Holguín province.
Assuntos
Cromossomos Humanos Par 12 , Genes , Degenerações Espinocerebelares/genética , Adolescente , Adulto , Idade de Início , Idoso , Criança , Mapeamento Cromossômico , Troca Genética , Cuba/epidemiologia , DNA Satélite/genética , Feminino , Efeito Fundador , Haplótipos/genética , Humanos , Desequilíbrio de Ligação , Escore Lod , Masculino , Pessoa de Meia-Idade , Linhagem , Reação em Cadeia da Polimerase , Degenerações Espinocerebelares/epidemiologiaRESUMO
We tested the frequency of the delta F508 mutation and haplotypes linked to the cystic fibrosis (CF) gene in Cuba. The delta F508 deletion was detected in 34.0% of the CF chromosomes. There was a shortage of delta F508 heterozygotes, suggesting non-randomness in mating patterns. Haplotype B (XV2C/KM19 1/2) was found on 40.5% of the CF chromosomes (71.5% of delta F508 chromosomes, 28.3% of non-delta F508 CF chromosomes) against 13.5% of non-CF chromosomes.
Assuntos
Fibrose Cística/genética , Haplótipos , Mutação , Cuba , Ligação Genética , HumanosRESUMO
A nationwide programme for the prevention of sickle cell (SS and SC) disorders was initiated in Cuba in 1983. Couples at risk were identified by screening pregnant women and the partners of those who carry an abnormal haemoglobin, followed by genetic counselling and the offer of prenatal diagnosis. Prenatal diagnosis was performed in one laboratory, which had carried out 1068 prenatal tests for Hb SS and SC disorders by the end of 1992. The centralization of the service has permitted rapid identification and resolution of problems.
Assuntos
Anemia Falciforme/diagnóstico , Hemoglobina Falciforme/genética , Diagnóstico Pré-Natal , Amniocentese , Anemia Falciforme/genética , Amostra da Vilosidade Coriônica , Cuba , DNA/análise , Feminino , Globinas/genética , Humanos , Reação em Cadeia da Polimerase , Gravidez , Fatores de RiscoRESUMO
Machado-Joseph disease (MJD) and Holguin ataxia (SCA2) are autosomal dominant multisystem degenerations with spinocerebellar involvement that are predominant among people of Portuguese-Azorean and of Cuban descent, respectively. Their clinical distinction may at times be difficult to make in individual patients, due to significant phenotypic overlapping (similar overall age-of-onset and duration of cerebellar ataxia, eye movement, and, often, other common problems. The recent mapping of SCA2 to chromosome 12q provided another candidate region for linkage studies of MJD. Original data on 10 families with Holguin ataxia show that the locus for phenylalanine hydroxylase (PAH) on chromosome 12q is linked to SCA2 at 4 cM and is thus far its closest marker. The exclusion of linkage 15 cM on each side of PAH in 16 families with MJD shows that these two forms of dominant ataxia are genetically distinct and at different chromosomal locations (nonallelic).
