Presence of the RET Cys634Tyr mutation and Gly691Ser functional polymorphism in Iranian families with multiple endocrine neoplasia type 2A.

PURPOSE: Multiple Endocrine Neoplasia type 2A (MEN2A) is a complex autosomal dominant inherited syndrome characterized by medullary thyroid carcinoma (MTC), pheochromocytoma and primary parathyroid hyperplasia. In patients with only one or two clinical features, identification of a germ line RET (REarranged in Transfection) mutation is required to make the diagnosis and initiate genetic counseling. METHODS: We analyzed blood DNA from three Iranian families with three generations of MEN2A including 20 affected individuals with MTC and four with pheochromocytoma. RET hotspots were amplified in probands and sequenced for mutation detection. RESULT: The causative mutation in all families was found to be the Cys634Tyr missense substitution. The presence of a functional SNP resulting in Gly691Ser was also detected in exon 11 of 15 affected cases. Four patients showed both of these RET variations. CONCLUSION: Our study shows that the Cys634Tyr missense substitution and the Gly691Ser polymorphism are recurrent in Iranian patients, since our families are unrelated. All asymptomatic carriers of the Cys634Tyr high-risk activating mutation were referred for prophylactic thyroidectomy.

Study on KAL1 Gene Mutations in Idiopathic Hypogonadotropic Hypogonadism Patients with X-Linked Recessive Inheritance.

Idiopathic hypogonadotropic hypogonadism (IHH) is a condition caused by low doses of hypothalamic gonadotropin-releasing hormone (GnRH) leading to absence or incomplete sexual maturation. One of the disorders leading to IHH is Kallmann syndrome which is characterized by GnRH deficiency with anosmia or hyposmia. This disorder generally occurs as a hereditary syndrome with X-linked recessive inheritance pattern. However, autosomal dominant or recessive and sporadic cases have also been reported. KAL1 is the most common mutated gene among these patients. The aim of this study was to determine the mutation spectrum of KAL1 gene in twenty patients. KAL1 exons were amplified by PCR method and the products were assessed by high resolution melting (HRM) technique. In addition, for one of the patients, all coding exons of the KAL1 gene were sequenced. Deletion of exons 4, 5 and 6 were evident in 5%, 10%, and 10% of patients, respectively. Furthermore, HRM results showed hemizygous mutation of exon 12 with more than 95% probability in 25% of patients. Finding these mutations could be helpful in the early diagnosis and presymptomic treatment of Kallman syndrome.