Overview of repeats

In a study conducted by Tan and colleagues (Tan et al., 2023) a association between CAG repeat expansions in the THAP11 gene and the disease was found. The median age of onset for ataxia symptoms was 34 years (range 4-51 years) and for individuals in the ataxic stage, the number of expanded CAG repeats ranged from 47 to 92, with one patient exhibiting as many as 100 repeats. Those in the preataxic stage had CAG repeats between 51 to 59. In contrast, unaffected family members had CAG repeat sizes ranging from 17 to 34. The most common sizes among the unaffected individuals were 28 and 29 repeats, accounting for 78.7% of the cases.
The study also included a comparison with healthy control subjects and patients with neurological disorders other than SCA. Among 500 healthy controls, the CAG repeat sizes in the THAP11 gene ranged from 20 to 38, and in 2144 non-SCA neurological patients, the range was 20 to 42. An analysis of the CAG repeat substructure revealed that healthy control subjects typically had 5 to 6 CAA interruptions and a median of 10 pure CAG repeats at the 3′ end. In contrast, SCA patients had fewer CAA interruptions (3) and a markedly higher number of 3′ pure CAG repeats (32 to 87). A strong correlation was found between earlier disease onset and increased number of expanded CAG repeats, as well as the length of 3′ pure CAG repeats.

→ View STRipy's population-wide repeat data for THAP11 locus