Skeletal dysplasia

Gene: TDP2

Green List (high evidence)

ID is part of the phenotype: 4 families with 6 affected patients, with functional evidence.

1 family with 3 affected sibs with homozygous splice site mutation in the TDP2 gene. Patient cell extracts showed absence of the full-length TDP2 protein and absence of 5-prime TDP activity, consistent with a loss of function, although 3-prime TDP activity, conferred by TDP1, was normal. In addition, patient lymphoblastoid cells were hypersensitive to the TOP2 poison etoposide. The findings indicated impaired capacity for double-strand break repair.

1 unrelated Egyptian patient with a similar disorder was homozygous for a truncating mutation in the TDP2 gene

1 unrelated Caucasian patient with same homozygous splice site mutation in the TDP2 gene. Western blot analysis did not detect TDP2 protein in patient primary skin fibroblasts. Patient fibroblasts showed an inability to rapidly repair topoisomerase-induced DNA double-strand breaks in the nucleus and also showed a profound hypersensitivity to this type of DNA damage. Complementation of patient cells with recombinant human TDP2 restored normal rates of nuclear DSB repair.
Sources: Expert list

Created: 14 Jan 2020, 9:39 a.m.

Mode of inheritance
BIALLELIC, autosomal or pseudoautosomal

Phenotypes
Spinocerebellar ataxia, autosomal recessive 23; OMIM #616949

Publications

• 31410782
• 30109272
• 24658003