Endocrine Abstracts

Kennedy’s Disease (KD) or Spinal and Bulbar Muscle Atrophy is a rare X-linked recessive condition due to CAG repeat in the androgen receptor (AR) gene. KD affects males with unaffected female carriers. Reported prevalence in male populations is highly variable; recent data suggests 2.5 in 100,000 with region specific higher prevalence. KD manifests as androgen insensitivity (AI) with features including gynaecomastia and motor signs such as early tremor, facial and bulbar muscle dysfunction, and slowly progressive proximal limb weakness. We present a 16 year old male with marked gynaecomastia. He had normal birth, met milestones and developed normally with no other relevant personal history. He was eugonadal and euthyroid. Most notable observation was marked upper limb tremor but no other motor symptoms. Testosterone 54 nmol/l with correspondingly high LH (13.0 IU/l), and normal oestradiol (182 pmol/l). Other pituitary hormones normal, including prolactin (267 mIU/l). Beta-HCG, US testes, MRI adrenals/pituitary normal. Several male relatives were previously diagnosed with motor neuron disease (MND) with unaffected females, suggesting X-linked inheritance. Given this family history (FH), in combination with AI and tremor, he was referred to neurology and genetics. Initial analysis of the AR gene was negative for abnormalities, but specific KD abnormality testing confirmed diagnosis. Patient’s priority was excision of gynaecomastia to good effect. KD is often misdiagnosed as MND due to features of progressive motor neuropathy in some patients. We should be mindful that KD is likely underdiagnosed due to rarity and limited awareness so actual prevalence could be underestimated. Gynaecomastia and tremor may be the sole early manifestations. Genetic testing for KD should be considered in men with AI with a relevant FH or with tremor or motor neuropathy. Specific analysis for KD genetic abnormalities should be requested as initial AR gene analysis may be normal.