Biallelic germline mutations in the mismatch repair genes MLH1, MSH2, MSH6 or PMS2 cause a recessive childhood cancer syndrome characterised by early-onset malignancies and signs reminiscent of neurofibromatosis type 1 (NF1).
Homozygous PMS2 germline mutations in two families with early-onset haematological malignancy, brain tumours, HNPCC-associated tumours, and signs of neurofibromatosis type 1.