Huntington disease-like 2: insight into neurodegeneration from an African disease

Atypical Presentations of Huntington Disease‐like 2 in South African Individuals

“… 8 The population studied included an individual with, to our knowledge, the largest ever reported repeat length (14/63). 4 In addition, the median repeat length (52) of the study population is significantly larger than the median of 46, which has previously been recorded from a group of patients from Northern Southern Africa who had typical features of HDL2. 2 The average AAO in this study was 34 years, considerably lower than the 41 years recently reported as being the typical age at onset of motor symptoms.…”

“… 2 The average AAO in this study was 34 years, considerably lower than the 41 years recently reported as being the typical age at onset of motor symptoms. 4 Furthermore, we report two unique cases of juvenile onset HDL2 (ages 18 and 19), noting that an AAO younger than 20 years has not been previously documented.…”

“…Of note, A‐IV‐7 had the largest repeat length (63) reported, and manifested with symptoms at the age of 18. 4 A‐IV‐8 and A‐II‐3, who were 19 and 25 years old, respectively at presentation, both had repeat lengths of 59. The median repeat length of 52 was significantly greater that that derived from a previously reported group of patients from Northern South Africa, predominantly of black Southern African origin (median repeat length, 46, P = 0.008).…”

“… 3 Unaffected individuals have 6 to 28 CTG triplets, whereas full penetrance occurs in individuals with 40 repeats or more. 4 HDL2 appears to affect only those with African ancestry from sub‐Saharan Africa, although cases have been identified in the Americas and Europe.…”