A very rare Kennedy disease genotype in a Norwegian family

Kennedy’s disease is a degenerative disease transmitted in a X-linked recessive mode. The case of two sisters who both inherited two pathological alleles of the gene encoding the androgen receptor (AR) is reported by Norwegian researchers :

  • both sisters had received a pathological allele from their mother, herself a transmitter, and another pathological allele from their father, himself suffering from the disease,
  • their respective genotype therefore corresponded to 43/43 and 43/45 repeats of CAG triplets
  • despite this composite heterozygosity, the phenotype observed with a 21-year follow-up was relatively mild, the symptomatology being limited to tremor of the extremities and fasciculations, all associated with chronic pain and cramps with minimal changing over time.


Kennedy disease in two sisters with biallelic CAG expansions of the androgen receptor gene. Müller KI, Nilssen Ø, Nebuchenykh M, et al. Neuromuscul Disord. 2021 Nov 19:S0960-8966(21)00705-7.