We describe a 30-year-old patient with acanthosis nigricans, diabetes mellitus with insulin resistance, hypogonadotropic hypogonadism, pigmentary degeneration of the retina and cerebellar, pyramidal and posterior columnar involvement. He had normal mental function, normal hearing and no hexadactyly. The patient had symptoms of both Bardet-Biedl and Alström syndromes, but did not manifest all the main features of either syndrome. This suggests either that the Bardet-Biedl, Alström, Laurence-Moon syndromes (including the variant described by Edwards) have a highly variable expression or that our case is a new variant within this group of syndromes.