NBS | BS | AT | |
Gene locus | 8q21 | 15q26 | 11q22–23 |
Gene | NBS1 | BLM | ATM |
Microcephaly | ++ | ++ | − |
Growth retardation | ++ | ++ | ± |
Mental retardation | ± | − | ± |
Typical facial appearance | ++ | − | − |
Telangiectasia | |||
Ocular | ± | − | ++ |
Cutaneous | ± | + | ++ |
Skin abnormalities | |||
Hyperpigmentation | + | + | + |
Sunlight sensitivity | + | ++ | − |
Cerebellar ataxia | − | − | ++ |
Recurrent infections | ++ | ± | ++ |
Elevated α fetoprotein levels | − | − | ++ |
Immunodeficiency | ++ | + | + |
Cancer predisposition | ++ | ++ | + |
Chromosomal instability | ++ | ++ | ++ |
Radiation hypersensitivity | ++ | − | ++ |
−, absent; ±, rare; +, usual; ++, frequent.