These include ataxia telangiectasia, which results from mutations in the ATM gene112; ataxia telangiectasia like disorder 1, which results from mutation in the MRE11 gene113; Nijmegen breakage syndrome, which results from mutations in the Nibrin (NBN) gene113; Seckel syndrome, which results from mutation of the ATR gene; Bloom syndrome caused by a mutation in the BLM gene114,115; Werner syndrome, which is caused by mutation in the WRN gene116; inflammatory bowel diseases117; collagen vascular diseases118; and others. The gene discussed is NBN; the disease is microcephalic primordial dwarfism.