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Acatalasia, a disease due to homozygosity for a Mendelian gene, is characterized by the absence of the enzyme catalase from the tissues of the human body. Red cells from heterozygotes have enzyme activities about one-half normal. In this paper, the development of cell lines from skin biopsies on an affected homozygote, a heterozygote, and eight control patients is described. The cell type is the euploid "fibroblast." It was found that acatalasic cells lacked the enzyme, even after growing for many months in a medium rich in catalase. The control lines all had mean catalase activities double or more that of the heterozygous line. Selection experiments, in which the growth of cells exposed for 20 minutes to varying concentrations of hydrogen peroxide was measured, did not provide a system for preferentially eliminating acatalasic cells. Certain other experiments bearing on the enzymatic defect in this disease were performed.

Prenatal diagnosis of chromosomal and many enzymatic-metabolic diseases is now possible, with little apparent risk. Studies may be carried out on the supernatant amniotic fluid, on the amniotic fluid cells directly, and on cultivated amniotic fluid cells.

THE PURPOSE of this paper is to present, for the first time, the ocular pathological manifestations of infantile or type 1 GM1-gangliosidosis (also known as generalized gangliosidosis). In addition, the clinical aspects of this disease will be discussed, since it has important ocular manifestations, but has received only one brief mention in the ophthalmic literature.1GM1-gangliosidosis is one of the inborn errors of metabolism, associated with the abnormal storage of two substances, one a ganglioside, and the other a mucopolysaccharide. More than 20 established cases now appear in the literature.2-15 In none of these were the eyes examined histopathologically.The earliest well-documented reports of GM1-gangliosidosis appeared in 1959,2,3 followed by seven cases in 1964.5 However, it was not until 1965 that a storage substance was identified as a ganglioside by O'Brien et al.6 An abnormally high accumulation of the ganglioside was

Histidinemia was detected in a Negro girl through a multiple screening process which selected out families having more than one child with learning disorders. Studies of 18 randomly selected asymptomatic Negro children failed to demonstrate a significant racial variation in blood histidine levels; the mean for the group studied was 0.92 mg/100 ml compared to a range of 0.49 to 1.66 mg/100 ml previously recorded among populations of mixed racial origin.