Congenital cataract in a child with pyridoxine-dependent epilepsy.

Pyridoxine-dependent epilepsy (PDE) is a cause of neonatal epileptic encephalopathy not previously known to cause ophthalmic disease. We describe the novel observation of a 5-year-old girl with pyridoxine-dependent epilepsy and bilateral cataracts. PDE is the result of mutations in the ALDH7A1 gene encoding antiquitin, an enzyme protective against cellular dehydration and osmotic stress. Accumulating metabolic precursors in PDE have been shown to be cataractogenic in vitro, and experimental pyridoxine deficiency has been associated with lenticular opacities in vivo. The association of ALDH7A1 haploinsufficiency in PDE and congenital cataract may offer insight into the relationship between osmotic stress and fetal cataract development. Bilateral progression of cataracts in this child suggests ongoing metabolic dysregulation within the crystalline lens despite pyridoxine supplementation at doses sufficient to control seizure activity.