BACKGROUND AND PURPOSE: The aim of this study was to perform DNA analysis in 
patients with clinical diagnosis of Huntington's disease (HD) after molecular 
exclusion of HD and further molecular examinations for other neurodegenerative 
diseases such as Huntington's disease-like 2 (HDL-2; gene JPH3), dentatorubral 
pallidoluysian atrophy (DRPLA; gene ATN1) and spinocerebellar ataxia type 17 
(SCA17; gene TBP).
MATERIAL AND METHODS: The material comprised 224 DNA samples isolated from 
peripheral blood from patients suspected of HD and 100 DNA samples from 
unaffected controls. The control group was used to determine the normal range of 
the number of CAG/CTG repeats in genes JPH3, ATN1 and TBP in the Polish 
population. Molecular analysis was carried out by PCR reaction, embracing 
microsatellite repeats in genes JPH3, ATN1 and TBP with specific, fluorescently 
labelled primers. PCR products were separated in polyacrylamide gels. The normal 
ranges of the number of repeats established for the control group in genes JPH3, 
ATN1 and TBP were 7-19, 9-27 and 29-45, respectively.
RESULTS: Molecular analysis of DNA from 224 individuals suspected of HD (117 
women and 107 men) revealed one case of dynamic mutation - 55 CAG repeats - in 
the TBP locus (SCA17). No cases of DRPLA or HDL-2 were detected. The range of 
CAG/CTG repeats for the JPH3 gene in the patient group was 11-19, with the most 
common alleles containing 14 and 16 repeats. For the ATN1 gene in patients the 
range of 8-27 repeats was established and the most frequent allele with 16 
triplets was present.
CONCLUSIONS: The study on 244 patients referred with the clinical diagnosis of 
HD and without mutation of the IT15 gene revealed one case of SCA17 but did not 
disclose the presence of two other diseases with a similar clinical 
manifestation: DRPLA and HDL2.