NEONATAL VITAMIN-K ADMINISTRATION AND IN-VIVO SOMATIC MUTATION

The glycophorin A (GPA) mutation assay was used to examine the risk of in vivo somatic mutation in infants following neonatal administration of vitamin K. The assay assesses damage to erythroid stem cells by me asuring the frequency of NO and NN variant red cells of MN blood group heterozygotes using FAGS analysis. Blood samples were obtained from 1 78 infants aged between 10 and 183 days. Twenty-six children were excl uded from study having received a blood transfusion. Sixty-four of the remaining 152 infants were of the MN phenotype, samples from whom wer e analysed using the assay system, providing the first data of NO and NN variant frequencies (vfs) in children aged less than 1 year. Twenty of these 64 infants received vitamin K orally (group A), 17 intramusc ularly (group B) and 25 intravenously (group C). Results were compared with those from a reference population of children aged 1-15 years. T here were no significant differences in NO, NN and total vf between an y of groups A, B and C. For all groups both NO and total vf were signi ficantly lower than those for the control population. This result is o f some interest and clearly warrants further investigation. NN and tot al vfs were greater than the 95th percentile for the pooled data from groups A, B and C in three instances, one in each group. It was thus n ot possible to demonstrate an association between the route of vitamin K administration and an increase in mutation at the GPA locus.