|
Genetic markers for retinitis pigmentosa
DY Wang, WM Chan, POS Tam,
SWY Chiang, DSC Lam, KKL Chong, CP Pang
Department of Ophthalmology and Visual Sciences, The Chinese University
of Hong Kong, Hong Kong Eye Hospital, 147K Argyle Street, Hong Kong
OBJECTIVE. To review recent advances in the molecular
genetics of retinitis pigmentosa with emphasis on the development
of genetic markers that aids diagnosis and prognosis.
DATA SOURCES AND EXTRACTION. Literature search of
MEDLINE from 1988 to 2005 using the following key words: ‘retinitis
pigmentosa’, ‘rhodopsin’, ‘RP1’,
‘RPGR’, and ‘genetic counseling’. References
of two genes—RHO and RP1—causing retinitis
pigmentosa in the Chinese population were reviewed.
STUDY SELECTION. Literature and data related to
genetic markers for retinitis pigmentosa.
DATA SYNTHESIS. The genetics of retinitis pigmentosa
is complex. It can be sporadic or familial, with heterogeneous transmission
modes. Retinitis pigmentosa is associated with nearly 40 chromosomal
loci, where 32 candidate genes have been identified. A large number
of mutations are known to cause retinitis pigmentosa. But no single
mutation alone accounts for more than 10% of unrelated retinitis
pigmentosa patients. Genetic tests for retinitis pigmentosa require
screening for a consort of mutations in a large number of genes.
High throughput screening technology such as denaturing high performance
liquid chromatography and automated DNA sequencing should make such
tests feasible.
CONCLUSIONS. Rapid developments in the understanding
of the genetics of retinitis pigmentosa have helped to establish
genetic tests of clinical value. The complex mode of inheritance
nonetheless makes genetic counselling difficult, even in the presence
of positive genetic screening results.
Hong Kong Med J 2005;11:281-8
Key words: Genetic counseling; Genetic heterogeneity;
Retinitis pigmentosa
|
