RESUMEN
OBJECTIVE: Huntington's disease (HD) has been reported to occur rarely in black patients. A new genetic variant- Huntington's disease-like 2 (HDL2)--occurring more frequently in blacks, has recently been described. The absence of an expanded trinucleotide repeat at the chromosome 4 HD locus was previously regarded as a way of excluding classic HD. The objective of this paper is to describe a number of black patients with genetically proven HD and to review its occurrence in Africa. METHODS: Eleven black families (12 subjects), with genetically proven HD, are described: 9 from the Dr George Mukhari Hospital, and 2 from private practice in Tshwane. RESULTS: Chorea was present in all 12 patients and cognitive decline in 9. Nine had an age of onset between 30 and 50 years. Six families exhibited expansion of the trinucleotide repeat at the chromosome 4, IT 15 gene (HD), and 5 a junctophilin (JPH3) trinucleotide expansion at chromosome 16 (HDL2). The HDL2 subtype showed a tendency towards a later age of onset. CONCLUSIONS: The clinical presentation of the two genotypes (i.e. HD and HDL2) appears to be similar. The actual rate of occurrence of HD in blacks may require re-assessment. Considering the number of Huntington's chorea patients occurring in our area (Garankuwa), the possibility of clustering of the condition arises.
Asunto(s)
Población Negra/genética , Heterogeneidad Genética , Enfermedad de Huntington/genética , Adulto , Edad de Inicio , Cromosomas Humanos Par 4 , Femenino , Genotipo , Humanos , Proteína Huntingtina , Enfermedad de Huntington/epidemiología , Masculino , Proteínas de la Membrana/genética , Persona de Mediana Edad , Proteínas del Tejido Nervioso/genética , Proteínas Nucleares/genética , Sudáfrica/epidemiología , Sudáfrica/etnología , Expansión de Repetición de TrinucleótidoRESUMEN
"Huntington's disease has been reported to occur rarely in black patients. A new genetic variant ""Huntington's disease like 2"" (HDL2); occurring more frequently in Blacks; has recently been described. The absence of an expanded tri-nucleotide repeat at the chromosome 4 HD locus was previously regarded as a way of excluding classical Huntington's disease (HD). The objective of this paper is to describe a number of black patients with genetically proven Huntington's disease and review its occurrence in Africa. Methods: Eleven black families (twelve subjects); with genetically proven Huntington's disease are described; nine from the Dr George Mukhari Hospital and two from private practice in Tshwane. Results : Chorea was present in all 12 patients and cognitive decline in nine. Nine had an age of onset between 30-50 years. Six families exhibited expansion of the trinucleotide repeat at the chromosome 4; IT 15 gene (HD) and five a Junctophilin (JPH3) trinucleotide expansion at chromosome 16 (HDL2). The HDL2 subtype showed a tendency towards a later age of onset. Conclusions: The clinical presentation of the two genotypes (i.e.; HD or HDL2) appears to be similar. The actual rate of occurrence of Huntington's disease in Blacks may require reassessment. With the number of Huntington's chorea patients occurring in our area (Garankuwa); the possibility of clustering of the condition arises."