A recent Finnish study identifies a low-penetrance gene defect which predisposes carriers to intracranial tumors called pituitary adenomas. In particular individuals carrying the gene defect are susceptible to such tumors which secrete growth hormone. Excess of growth hormone results in conditions called acromegaly and gigantism. Identification of this gene defect using DNA-chip technologies is an example how genetic research can tackle more and more demanding tasks, such as identification of predisposition genes conferring a low absolute but high relative risk. The results are published in the May 26 issue of the journal Science.

The research group, lead by professor Lauri Aaltonen (University of Helsinki, Finland) and Dr Outi Vierimaa (Oulu University Hospital, Finland) providing the initial observations leading to the investigations, aimed at unravelling the genetic basis of susceptibility to pituitary adenomas. Pituitary adenomas are common benign neoplasms, accounting for approximately 15 % of intracranial tumors.

Most common hormone-secreting pituitary tumor types oversecrete prolactin or growth hormone (GH), which together with local compressive effects account for their substantial morbidity. Oversecretion of GH causes acromegaly or gigantism. Acromegaly is characterized by coarse facial features, protruding jaw, and enlarged extremities. The potentially severe symptoms of untreated acromegaly, develop slowly and the condition is difficult to diagnose early. Gigantism refers to excessive linear growth occurring due to GH oversecretion when epiphyseal growth plates are still open, in childhood and adolescence. Genetic predisposition to pituitary tumors has been believed to be rare.

The researchers detected three clusters of familial pituitary adenoma in Northern Finland. Genealogy data reaching back to 1700's was available. Two first clusters could be linked by genealogy. The researchers hypothesized that a previously uncharacterized
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Contact: Lauri A. Aaltonen
lauri.aaltonen@helsinki.fi
358-50-930-1880
University of Helsinki
25-May-2006

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