Rod-Cone Dystrophy, Sensorineural Deafness, And Fanconi-Type Renal Dysfunction

During a large-scale survey of persons with Usher syndrome (retinitis pigmentosa and sensorineural deafness), Beighton et al. (1993) identified 14 children in 9 Afrikaner families in South Africa with a combination of progressive rod-cone dystrophy, sensorineural deafness, and renal dysfunction of the Fanconi type leading to rickets-like skeletal changes and renal failure. Eight of the 11 children had died between the ages of 3 and 20 years; in most patients, the cause of death was reported to be renal failure. Onset of auditory and visual dysfunction was usually before age 5 and invariably before age 10 years. Retinitis pigmentosa or Usher syndrome had initially been diagnosed in every child, and cataracts had been documented as a complicating factor in 4 of the children. Renal dysfunction usually presented with albuminuria during the first 5 years, and the skeletal complications of 'renal rickets' were generally evident during the first decade. A stunted stature and malalignment of the weightbearing bones were the major skeletal manifestations. None of the parents were affected. Although minor changes were found in the eyes of the father of 2 affected sibs, none of the parents were known to be consanguineous. However, the Afrikaner population, which now numbers more than 3 million, is derived from a comparatively small number of founders.