{'fraction_non_alphanumeric': 0.06635388739946381, 'fraction_numerical': 0.04088471849865952, 'mean_word_length': 4.257042253521127, 'pattern_counts': {'":': 0, '<': 1, '<?xml version=': 0, '>': 2, 'https://': 0, 'lorem ipsum': 0, 'www.': 0, 'xml': 0}, 'pii_count': 0, 'substrings_counts': 0, 'word_list_counts': {'cursed_substrings.json': 0, 'profanity_word_list.json': 0, 'sexual_word_list.json': 0, 'zh_pornsignals.json': 0}}
HOMOCYST INURIA DUE TO CYSTATHIONINE SYNTHASE (CS) DEFICIENCY: INVESTIGATIONS IN CULTURED LONG-TERM LYMPHOCYTES, FETAL SKIN FIBROBLASTS AND AMNIOTIC FLUID CELLS

Systematic delineation of optimal assay conditions for CS in adult skin fibroblasts (fib.) enabled us to differentiate obligate heterozygotes (het.) from affected individuals and controls (BBRC 55:38, 1973). We have now extended our studies to long-term lymphoid lines (LTL) and cultured fib. of fetal origin. We have detected CS activity in LTL from 12 normal donors (mean ± SEM=9.49 ± 0.98 nmoles/mg prot./h), its deficiency in a line from an affected individual (0.88), and intermediate activity in 3 obligate het. lines (3.21 ± 0.37), with no overlap. Activity in skin fib. from 5 control fetuses was 32.9 ± 5.06 and not different from control amniotic fluid (AF) cell cultures (40.7 ± 4.58) (.25>p>.01); both differed from adult skin fib. (21.0 ± 1.71) (p < .001). Activity in AF cells from an obligate het. mother was 73.8; prenatal diagnosis of a normal fetus was confirmed after birth by assay of skin fib. Thus: (1) LTL, which proliferate vigorously in apparently permanent cultures, are ideal for detection and study of the enzymatic defect in homozygotes and het. for CS deficiency. (2) CS values from adult skin fib. cannot be used as controls for AF cells. (3) Requirements for prenatal diagnosis of CS deficiency have now been met. (4) CS activity in het. LTL, as in liver and skin fib., was less than 50% of normal.