Isolated Follicle-Stimulating Hormone Deficiency Caused By a New Missense Mutation in the FSHb Gene in a Male Adolescent with Normal Virilisation

Presentation Number: THR-114
Date of Presentation: March 5th, 2015

Enver Simsek*1, Luciana Ribeiro Montenegro2, Cigdem Binay1 and Ana Claudia Latronico3
1Eskisehir Osmangazi University School of Medicine, Eskisehir, Turkey, 2Division of Endocrinology and Metabolism, São Paulo, Brazil, 3Sao Paulo Medical School, University of Sao Paulo, Sao Paulo-SP, Brazil

Abstract

Background: Few male patients with selective hypogonadotropic hypogonadism due to FSH deficiency have been reported.

Objective: To describe the clinical, hormonal and genetic analysis of a male adolescent with isolated FSH deficiency.

Patient and Methods: Clinical, hormonal and genetic features of a male adolescent with short stature and small testicular. Amplification and automatic sequencing of the three exons of the FSH beta gene were performed.

Case Report: A 14.5-years-old boy presented with short stature. His past-medical history and family history were unremarkable. On physical examination, weight was 38 kg (-1.83 SDS); height, 146 cm (-2.39 SDS); BMI, 16.5 (-0.58 SDS); axillar hair, Tanner stage II, pubic hair, Tanner stage V, testicle sizes 1/1 ml (Tanner stage I). Bone age was 13.5 years old. Thyroid function tests were in normal references. IGF-1 was 343 ng/ml (N, 268-512); FSH, 0.12 mIU/ml; LH, 22.3 mIU/ml; total testosterone 261 ng/dl; inhibin B 31.5 pg/ml (N, < 360 pg/ml); and anti-Mullerian hormone 4.4 ng/ml (N, 4.0-169 ng/ml). GnRH stimulating test revealed that peak LH and FSH levels were 298 mIU/ml and 0.14 mIU/ml, respectively. According to the findings of physical examination and hormonal tests, isolated FSH deficiency was suspected. The diagnosis was confirmed by molecular genetic study. A new homozygous missense mutation (c.364T>C resulting in p.Cys122Arg) in the FSHß was identified in this patient.

Discussion and Conclusion: We described a male adolescent with typical selective hypogonadotropic hypogonadism due to FSH deficiency confirmed by genetic study. Notably, the small testicular size contrasts with normal virilisation and pubertal testosterone levels in the affected patients by this very rare genetic condition.

 

Nothing to Disclose: ES, LRM, CB, ACL