What is the relation between the nature and symptoms of xeroderma pigmentosum and ataxia telangiectasia ?

Deficiency in some : part of cell mechanisms that detect & repair damage to DNA molecules that encode their genome occur in 5 inherited diseases: ataxia-telangiectasia (AT), Fanconi anemia, Bloom syndrome, Cockayne syndrome & Xeroderma Pigmentosum (XP).7 different mutant repair genes cause XP; types A, C, D & E are on Chromosome 9q.22. Mutations in ATM genes cause AT. Groups A,C,D & E are on Chromosome 11q2.