Huntington's disease: genetic heterogeneity in black African patients.
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.
Magazi
D S
DS
Department of Neurology, Dr George Mukhari Hospital, University of Limpopo (Medunsa campus), Gauteng. dalim@medunsa.ac.za
Krause
A
A
Bonev
V
V
Moagi
M
M
Iqbal
Z
Z
Dludla
M
M
van der Meyden
C H
CH
D000328:Adult; D017668:Age of Onset; D044383:Black People / Q000235:genetics*; D002894:Chromosomes, Human, Pair 4; D005260:Female; D018740:Genetic Heterogeneity; D005838:Genotype; D006801:Humans; D000071058:Huntingtin Protein; D006816:Huntington Disease / Q000453:epidemiology / Q000235:genetics*; D008297:Male; D008565:Membrane Proteins / Q000235:genetics; D008875:Middle Aged; D009419:Nerve Tissue Proteins / Q000235:genetics; D009687:Nuclear Proteins / Q000235:genetics; D013019:South Africa / Q000453:epidemiology / Q000208:ethnology; D019680:Trinucleotide Repeat Expansion
C086055:HTT protein, human; D000071058:Huntingtin Protein; D008565:Membrane Proteins; D009419:Nerve Tissue Proteins; D009687:Nuclear Proteins; C412507:junctophilin