Exacerbation of the repair defect by Xpa ablation, on the other hand, results in a much more severe phenotype including dramatic postnatal growth retardation, progressive cerebellar ataxia, lack of subcutaneous fat, and death around weaning in several of these mouse models (e.g., XPCS/XPA, TTD/XPA, and CSB/XPA) [9,20,21]. The gene discussed is XPA; the disease is cerebellar ataxia.