STRs database » JPH3 locus
Overview of repeats
CTG repeat expansions in the JPH3 gene cause autosomal dominant Huntington's disease-like 2 (HDL2). Early reports described affected individuals with 41-58 repeats and normal alleles of 6-27 repeats (Holmes et al. (2001); Margolis & Holmes (2003)). Krause et al. (2015) subsequently reported expanded alleles of 40-58 repeats. The ranges used here are 6-28 repeats as normal, 29-39 as intermediate/uncertain significance, and 40 or more as pathogenic. The significance of 29-39 repeats and the penetrance of expanded alleles are not fully established (Anderson et al. (2025)).
Ramírez-García et al. (2025) studied five Mexican families, identifying nine symptomatic carriers with expanded alleles of 42-50 repeats and symptom onset at 31-54 years. Three additional carriers with 42, 49 and 50 repeats were asymptomatic at assessment, although their ages were not reported. All expansion carriers shared a founder haplotype inferred to be of African origin, most likely Yoruba.