Agammaglobulinaemia in a girl with a mosaic of ring 18 chromosome.

A patient with a mosaic karyotype 45,XX,-18/46,XX,dic r(18)/46,XX,r(18) with multiple phenotypic abnormalities and immunodeficiency was presented at the age of 14 years. Immunological investigation revealed markedly decreased IgG, IgA and in two of three evaluations also IgM levels. Although selective IgA deficiency is frequent in patients with a ring chromosome 18, this is the third patient described with decreased levels of other immunoglobulin isotypes. The association of chromosome 18 partial deletions and immunoglobulin abnormalities suggests the presence of an as yet unrecognised gene with a pivotal role for immunoglobulin production on chromosome 18.

Relationship between acetylator phenotype and intensity of the hypoglycaemic effect of a suplhonamide preparation in children with insulin-dependent diabetes.

The distribution of acetylator phenotypes was determined in 95 healthy children (4-15 y) and in 48 children with Type I diabetes (5-15) using the sulphadimidine test for the determination of acetylation capacity. The frequency of slow acetylators within the diabetic group (60.4%) closely resembled that in the healthy population (59.0%). There was no significant sex difference within either group. Subgrouping according to age showed a more marked preponderance of slow acetylators (65.0%) among children under six years of age on the control group but not in the diabetics (60.0%). Despite a relatively low dose of sulphadimidine used for acetylator phenotyping (20 mg/kg orally), a marked hypoglycaemic effect was observed in diabetics with slow but not with fast acetylator phenotype. The result appears to be coherent with the marked difference in the plasma concentrations of non-metabolized sulphadimidine which 6 h after the dose was 3.5-fold higher in slow acetylators than in fast ones. (Tab. 2, Fig. 1, Ref. 53.)

N-acetylation in healthy and diseased children.

Acetylation capacity was examined in three groups of Czech children by measuring the plasma and urine concentrations of sulphamethazine and its acetylated metabolite 6 h after an oral test dose of 20 mg/kg sulphamethazine. Amongst 82 healthy children aged 4-15 y there were 32 (39%) fast acetylators; there was no significant difference between the number of boys and girls, or between children over or less than 6 years of age. In 41 patients aged 3-15 y with phenylketonuria, the acetylation indices showed a significantly higher proportion of fast acetylators - 24 (58.5%) using plasma measurements and 29 (70.7%) using urine data. In them the ratio between slow and fast acetylators was inverted compared to normal children. The preponderance of fast acetylators was greater in boys than in girls and in children over 6 years of age. An increased acetylation capacity in patients with phenylketonuria was apparent even in individuals classified as slow acetylators, because in them the plasma concentration of the acetylated metabolite was higher than in control acetylators. Amongst 48 young patients (5-15 y) with insulin-dependent diabetes there were 19 (39.6%) fast and 29 (60.4%) slow acetylators, which corresponded well to the phenotype distribution in control children. This did not support the suggested association between the fast acetylator phenotype and Type I diabetes.