Abstract
Introduction: Hypogonadotropic hypogonadism is a common disorder encountered in endocrine practice with a prevalence of 1 in 10,000 men (1). We describe a patient with possible mitochondrial mutation causing him to have concurrent central hypogonadism and NARP syndrome (neuropathy, ataxia, retinitis pigmentosa). Case: 65 year old male with central hypogonadism diagnosed at age 17 was on testosterone replacement therapy off and on since then. He was diagnosed with NARP at age 49. On exam, he was OX3, BP 147/83mmHg, HR 63 bpm, wt 185lbs. Pupils were sluggish to light. Unable to assess visual fields as patient is legally blind. No gynecomastia. Cardiac and pulmonary exam were normal. Testicles were soft and the volume was 12mL. Prostate was enlarged, non tender and without nodules. He had ataxic gait, abnormal finger to nose test and strength was normal. LH <0.2 mIU/ml (N 1.2 - 10.6 mIU/ml), FSH < 0.2 mIU/ml (N 0.7 - 10.8mIU), total testosterone as low as 12ng/dL when off and 260ng/dL (N 250-1110ng/dL) while on testosterone IM. CBC, CMP, prolactin, ACTH, cortisol, Igf-I, TSH and PSA wnl. MRI brain showed cerebellar atrophy and normal pituitary. Discussion: NARP is a mitochondrial disorder characterized by neuropathy, ataxia and retinitis pigmentosa primarily affecting the nervous system. NARP results from point mutation at base pair 8993 of the mitochondrial genome in the ATPase 6 gene. Symptoms typically consist of proximal neurogenic muscle weakness, sensory neuropathy, ataxia, and retinitis pigmentosa. According to Al-Gadi et al, hypogonadism has been reported in mitochondrial disease (2). RRM2B is a nuclear-encoded mitochondrial maintenance gene. Mitochondrial DNA depletion due to ar-RRM2B mutations have been reported in association with hypogonadism. A mutation of m.8561C>G in MT-ATP6/8 causing a mitochondrial syndrome with ataxia, peripheral neuropathy, diabetes mellitus, and hypergonadotrophic hypogonadism has also been reported in a case report of two patients (3). Upon literature review, no prior cases of hypogonadotropic hypogonadism in patients with NARP have been reported. The impairment of the hypothalamic-pituitary axis appears to manifest in severe mitochondrial phenotypes. For example, the association of central hypogonadism with Kearns Sayre Syndrome (KSS). Given that both disorders are related to mitochondrial dysfunction, we propose that the hypogonadism may be linked to NARP syndrome. References Rohayem, J.et al. (2016), Causes of hypogonadotropic hypogonadism predict response to gonadotropin substitution in adults. Andrology Al-Gadi.et al. (2018). Endocrine Disorders in Primary Mitochondrial Disease. JES Kytövuori, L. et al. (2016, August 8). A novel mutation m.8561C>G in MT- ATP6/8 causing a mitochondrial syndrome with ataxia, peripheral neuropathy, diabetes mellitus, and hypergonadotropic hypogonadism.
Kearns-Sayre Syndrome: A Rare Mitochondrial Disorder
