Abstract
Machado-Joseph disease (MJD) is an autosomal dominant neurodegenerative disorder of late onset, caused by the expansion of a (CAG)n tract in the MJD1 gene. Using BLAST2 sequences between known cDNA variants transcribed by the MJD1 gene and a clone of human genomic DNA, six possible unknown intragenic single-nucleotide polymorphisms (SNPs), at variable positions in the MJD1 gene, were identified. To confirm this, we studied a Portuguese control population, using polymerase chain reaction amplification and single-strand conformation polymorphism analysis for each potential SNP. For four of the possible polymorphisms there was no variability in our population, but the existence of three novel polymorphisms was confirmed: GTT_527/GTC_527, C_1178/A_1178, and A_1294/G_1294. The polymorphism GTT_527/GTC_527 (Val/ Val) is located in the coding region, whereas C_1178/A_1178 and A_1294/G_1294 are located in the 3′noncoding region of cDNA variants of the MJD1 gene, MJD2-1 and MJD1-1, respectively. All these novel SNPs are in Hardy-Weinberg equilibrium. These intragenic polymorphisms can be useful for (1) the study of the origin of the MJD mutation(s), (2) the study of recombination events, (3) distinction of chromosomes with alleles of identical (CAG)n size in genetic tests (homoallelism), (4) the study of genetic modifiers in the region flanking the MJD1 gene, and (5) association studies in other diseases.
Similar content being viewed by others
Article PDF
Author information
Authors and Affiliations
Additional information
Received: December 19, 2001 / Accepted: January 28, 2002
Rights and permissions
About this article
Cite this article
do Carmo Costa, M., Sequeiros, J. & Maciel, P. Identification of three novel polymorphisms in the MJD1 gene and study of their frequency in the Portuguese population. J Hum Genet 47, 205–207 (2002). https://doi.org/10.1007/s100380200025
Issue Date:
DOI: https://doi.org/10.1007/s100380200025
This article is cited by
-
A multistep mutation mechanism drives the evolution of the CAG repeat at MJD/SCA3 locus
European Journal of Human Genetics (2006)