Genetic analysis of treated and untreated phenylketonuria in one family

We describe a family in which four subjects in two generations have a disorder of phenylalanine metabolism. Two first cousins had different biochemical presentations in the neonatal period. The older child was thought to have a more severe form of phenylketonuria (PKU), and the younger child a milder form. While carrying out family studies we discovered that their mutual grandfather and his older unmarried brother, both of normal intelligence, had a marked and previously undiagnosed hyperphenylalaninaemia. DNA analysis using RFLP haplotypes has shown that there are four independent mutant PKU alleles in this family which are found on three haplotype patterns. None of the affected family members carries a previously defined mutation at the phenylalanine hydroxylase (PAH) locus and so DNA analysis was not able to explain the apparently different biochemical phenotypes in the affected members of this family.

The glycaemic effect of simple sugars in mid-morning and afternoon snacks in childhood diabetes

Eighteen diabetic children ate three different snacks (free sucrose, sucrose plus fibre, fructose plus fibre) or had no snack on each of 4 mornings. Subsequently 10 children from this group took a standard snack (free sucrose) or no snack on two afternoons. In other respects the day of testing was standardised, the children going to school as normal and collecting their blood spots on filter paper for glucose analysis. There was no difference in the blood glucose profiles between different snacks or when no snack was taken either in the mornings or afternoon. This suggests both that moderate amounts of simple sugar do not have a detrimental effect on glycaemic control and that snacks can generally be omitted without serious hypoglycaemic problems.

Tapetoretinal degeneration in the cerebro-hepato-renal (Zellweger's) syndrome

Electrophysiological and histopathological study of a baby suffering from Zellweger's syndrome and presenting progressive retinal dysfunction showed this to be related to degenerative changes in the photoreceptor cells and pigment epithelium and to defective myelination of the optic nerve. Disturbances of bile acid and lysine metabolism were also demonstrated, lending support to the concept that Zellweger's syndrome is attributable to a widespread inadequacy of intracellular oxidative function.