Endocrine Abstracts (2007) 13 P107

Double Y syndrome as a cause of gynaecomastia

MO Sharfi, SS Nussey & G Bano


St Georges Hospital, London, United Kingdom.


A 68 year old retired accountant presented with loss of libido, reduced shaving frequency, obesity and gynaecomastia. His past medical history included osteoarthritis and facial acne. There was no related family history and he was taking no medications. He reported having two children.

On examination the BMI was 31.7 kg/m2 and height 181 cm. He was normotensive and bilateral gynaecomastia was noted. He has reduced body hair; testicular volume was 10 ml bilaterally and soft. The rest of his clinical examination was unremarkable.

Investigations revealed normal gonadotrophins FSH7.6 IU/L (N 1–10) LH5.0 IU/L (N 1–9) and low testosterone at 4.8 nmol/L (N 9–26) and normal gonadotrophins response to GnRH. His TSH was 4.0 mu/L (N 0.4–4) with low free T4 at 9 pmol/L (N 11–23). His prolactin, IGF1, renal and liver function were all within normal range. Bone density scan revealed T-score of −1.14 at lumber spine and 0.34 at hip. MRI pituitary was within normal limits. His chromosomal analysis revealed 47 XYY Karyotype. He was started on testosterone and thyroxine replacement.

The incidence of 47 XYY syndrome is 1:1000 male. Most often this chromosomal abnormality causes no unusual physical features or medical problems. Males with 47XYY syndrome are slightly taller than average with longer craniofacial measurements but normal body proportions. They have increased risk of learning disabilities and delayed speech and language skills. Most males with 47 XYY syndrome have normal sexual development and are able to reproduce.

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