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Isolated familial hyperparathyroidism with a novel mutation of the MEN1 gene.

OBJECTIVE
To describe two cases of familial hyperparathyroidism with genetic analysis and report a new gene mutation.


METHODS
Clinical and laboratory details of a brother and sister with hyperparathyroidism and nephrolithiasis are presented. The family history is reviewed, and results of direct sequencing analysis for mutations in the MEN1 gene are discussed.


RESULTS
Isolated familial hyperparathyroidism is uncommon. Whether this condition is a partial expression of multiple endocrine neoplasia type I, a well-known genetic disorder, or an independent entity is being debated and studied. Two cases of hyperparathyroidism were diagnosed in a brother and a sister from a family that has expressed isolated hyperparathyroidism in several family members as the only manifestation thus far. A novel genetic mutation involving a CGG to CGT alteration in codon 219 of the MEN1 gene was discovered; to our knowledge, this particular variation has not been reported previously.


CONCLUSION
In patients with isolated familial hyperparathyroidism, a search for a mutation in the MEN1 gene may eventually help clarify this uncommon familial condition.