Malignant neoplasms in the families of patients with ataxia-telangiectasia.
Ataxia-telangiectasia ( A-T ) is an autosomal recessive syndrome associated with a greatly increased incidence of malignant neoplasms in homozygous affected individuals . Heterozygotes for the gene for A-T are thought to comprise about 1 % of the general population and , therefore , it is important to know whether this gene also predisposes the heterozygous carrier to cancers . Heterozygous carriers of this gene are common among the close relatives of patients with A-T , although individual carriers cannot be identified by any clinical criterion or laboratory test . For this reason , we compared the incidence of death from malignant neoplasms in 2 families of patients with A-T to that expected in a random sample of the general population . There were 59 deaths from malignant neoplasms in relatives dying before age 75 , compared to 42 . 6 expected ( p less than 0 . 02 ) . For A-T heterozygotes younger than age 45 , the risk of dying from a malignant neoplasm was estimated to be greater than 5 times the risk for the general population . A-T heterozygotes may comprise more than 5 % of all persons dying from a cancer before age 45 . The incidence of ovarian , gastric , and biliary system carcinomas and of leukemia and lymphoma was increased in these A-T families . Other neoplasms that may be associated with this gene in heterozygotes include pancreatic , basal cell , colonic , breast , and cervical carcinomas .
