Serum cholinesterase (pseudocholinesterase) in Down's syndrome: 2. Quantitative levels.

The observation elsewhere (Drew and Rundle, 1977) that increase frequencies of the C5 + variant of the serum cholinesterase in Down's syndrome may be due to a protective influence against adverse environmental factors has been investigated for such factors as age, sex, duration of institutionalisation, presence of the hepatitis -B antigen and maternal age. With the exception of the maternal age none of the factors tested appear to affect the circulating levels of cholinesterase. A maternal age effect in the Down's subjects was detected with lower levels of the enzyme being found in the subject positive for the C5 + variant born to mothers over thirty-five years when compared to the C5 + subjects born to mothers under thirty-five years. Further studies confirmed the presence of a relationship between maternal age, serum cholinesterase levels and haptoglobin phenotypes.