Intergenerational De Novo Spinocerebellar Ataxia 7 CAG Enlargement in a Moroccan Family Detected by Triplet Primed PCR

The autosomal dominant cerebellar ataxias (ADCA) are a genetically and clinically heterogeneous group of neurodegenerative. Spinocerebellar ataxia type 7 (SCA7) is a progressive neurodegenerative disorder with retinal degeneration caused by a CAG expansion in the ATXN7 gene located in chromosome 3p. The normal range of CAG triplets is 4-34 considering diseased over 37 to 306. In order to study a possible de novo large expansion, a triplet primed SCA7 PCR assay was made in a family with characteristic clinical symptoms. This assay confirmed the disease number of triplets for the father and detects a second allele in his son (patient) with a large expansion (>200 triplets). In conclusion, the specific SCA triplet primed PCR is a robust, reliable, and can be used in this case to describe for the first time an intergenerational de novo SCA7 CAG large expansion.