Aniridia, ectopia lentis, abnormal upper incisors and mental retardation--an autosomal recessive syndrome

A 13-year-old boy presented with bilateral aniridia, ectopia lentis, two palatally placed upper incisors which may be supernumerary teeth or may be malpositioned lateral incisors, and mental retardation. The cause is very probably a single autosomal recessive gene defect although the mental state may have a separate, genetic cause. Since his parents, who are normal, are second cousins and his father's and his mother's parents are also full cousins, the coefficient of inbreeding is 1/64 which is only 25% of the coefficient for full cousinhood of parents alone (1/16). No biochemical correlate has been identified.