A meiotic recombination in a new isolated familial somatotropinoma kindred

We report here the genetic findings of a new isolated familial somatotropinoma (IFS) kindred in which the mother (subject I:2) and one daughter (subject II:2) are affected; their ages at diagnosis were 25 and 14 years respectively. Additionally, patient I:2 developed virilization due to an androgen-secreting adrenocortical mass, presenting clinical and molecular features of sporadic adrenal carcinoma. To genotype this family and to narrow down the candidate interval of the putative IFS gene at 11q13, we performed haplotyping on the DNA from all five members of the family and allelotyping of one available somatotropinoma using polymorphic microsatellite markers from chromosome region 11q12.1-11q13.5. Results indicated that the disease haplotype, between markers D11S956 and D11S527, was transmitted from subject I:2 only to subject II:2. A meiotic recombination event was detected in the fraternal twin sister of II:2 (subject II:1), but her disease status is unknown. Since she is only 18 years old this genetic event cannot yet narrow down the area involved in the pathogenesis of IFS. Allelotyping of the somatotropinoma from II:2 revealed loss of the chromosome carrying the wild-type copy of the putative IFS gene inherited from her father. These results support the involvement of a tumor suppressor gene at 11q13.1-q13.3 in the pathogenesis of IFS.