ABSTRACT
<p><b>OBJECTIVE</b>To determine the frequency of spinocerebellar ataxia type 31 (SCA31) related mutations among patients from mainland China.</p><p><b>METHODS</b>For a cohort of molecularly unassigned patients comprised of 295 SCA patients (including 98 probands from families featuring autosomal dominant SCA and 197 sporadic cases) and 81 patients with hereditary spastic paraplegia (HSP) (including 23 probands from families with autosomal dominant HSP and 58 sporadic cases),TGGAA pentanucleotide expansion insertional mutation of the BEAN/TK2 gene was detected using repeat-primed PCR followed by capillary gel electrophoresis.</p><p><b>RESULTS</b>No TGGAA pentanucleotide insertion expansion in BEAN/TK2 gene was identified in the above cohort.</p><p><b>CONCLUSION</b>SCA31 is an extremely rare subtype of SCA and should not be included in routine genetic screening in mainland China.</p>