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Editor—The hereditary spastic paraplegias (HSPs) are clinically characterised by progressive lower limb spasticity. The spasticity may occur in isolation (“pure”) or may be complicated by other major clinical features. Autosomal dominant, autosomal recessive, and X linked recessive inheritance patterns have been described for pure and complicated forms of HSP.1 ,2
There are loci for ADPHSP on chromosomes 2p (SPG4, MIM 182601),3 ,4 8q (SPG8, MIM 603563),5 ,6 14q (SPG3, MIM 182600),7 15q (SPG6, MIM 600363),8and 19q (SPG12).9 In addition, we recently mapped an ADPHSP locus on chromosome 12q13 (SPG10, MIM 604187) in a large UK family, family 4.10 This locus was narrowed to a 9.2 cM region between markers D12S368 and D12S83.
Clinical features and diagnostic criteria for family 4 have previously been described.10 ,11 Briefly, subjects were classified as being affected if they had lower limb hyperreflexia in addition to at least one of the following: progressive spastic gait abnormality, bilateral extensor plantar reflex, or bilateral sustained (⩾5 beats) ankle or knee clonus. Subjects were classified as being possibly affected if lower limb hyperreflexia was present without other abnormal signs and as being normal if they had an entirely normal neurological examination. Thirteen members of family 4 are affected by ADPHSP and the family has a relatively young mean age at onset of 10.8 (SD 9.6) years (range 8-40).
We have now genotyped additional markers D12S803, D12S390, D12S270, D12S1618, and D12S355 for subjects from family 4, using previously described methods.10 Primer sequences for these markers are available from the Généthon …