Homozygous mutations in MKKS cause Bardet‐Biedl syndrome, which manifests with polydactyly, obesity, retinitis pigmentosa and intellectual disability (Forsythe & Beales, 2003) or Mc‐Kusick Kaufman syndrome, associated with congenital heart disease, genitourinary abnormalities and polydactyly (Slavotinek, 2002). Here, MKKS is linked to retinitis pigmentosa.