[The blood galactokinase activity in Chinese with reference to congenital cataract]

The galactokinase (GK) activity of whole blood in Chinese volunteers and patients with congenital cataracts was studied by radioassay after Beutler. The GK activity was found to be highest 78.42 +/- 22.01 mU/g.Hb, in the newborn, and is decreased with age up to 4 years to remain constant thereafter at a mean normal value of 27.79 +/- 4.98 mU/g.Hb, which was consistent with Beutler's results. The frequency of GK heterozygotes in normal Chinese was found to be 1/234(0.43%). Among 55 children with congenital cataracts developed during the first year after birth, 4 (7.30%) were heterozygotes. Furthermore, the frequency of heterozygotes was found to be 3/16 (18.80%) in infants with nuclear cataracts, which differed very significantly from that of the normal Chinese. The probable association of congenital cataracts with decreased GK activity was discussed.