Abstract
We report a two-year-old boy who had undergone extirpation out of capsula lentis at 6 months of age because of his congenital catalact. On admission for examination of his mental retardation, his blood examination data showed elevated levels of serum alkaliphosphatase and creatine phosphokinase and high chloride iso-anion gap metabolic acidosis. His urine chemistry data showed hypercalcinuria, pan amino aciduria, and low molecular weitht proteinuria. A wrist X-ray examination showed the typical bone change of rickets on the distal side of the ulna. Although 99mTc-DMSA scintigraphy revealed no morphologically abnormal accumulation, total accumulation of radioisotope in the kidneys were poor. We diagnosed the patient as having typical Lowe syndrome and started him on alkali treatment. No phosphatidylinositol 4,5-bisphosphate 5-phosphatase activity was detectable in his fibroblast. We identified A to C mutation at base 1783 in exon 15 of OCRL-1 cDNA (GenBank M 88162). This mutation was predicted to cause an amino acid change from serine to arginine. The predicted amino acid change was located in well conserved motifs of the human inositol polyphosphate 5-phosphatase molecule. Therefore, it was speculated that the predicted change of the amino acid sequence would greatly influence the activity of phosphatidylinositol 4,5-bisphosphate 5-phosphatase.
