Gender-specific frequency of background somatic mutations at the hypoxanthine phosphoribosyltransferase locus in cord blood T lymphocytes from preterm newborns

Limited information is available regarding the frequency, spectrum, and cli nical relevance of somatic mutations in the developing fetus. The goal of t his study was to determine somatic mutant frequencies (Mfs) at the hypoxant hine phosphoribosyltransferase (HPRT) reporter gene in cord blood T lymphoc ytes from preterm infants to gain insight into in utero mutational events. Mf determinations were made by using the HPRT T cell cloning assay on cord blood samples from 52 preterm infants, Natural logarithm Mfs (InMfs) from p reterm infants were compared with results from our database for full-term i nfants. Our analysis revealed higher InMfs in cord blood T lymphocytes from preterm compared with full-term infants (P = 0.008), In addition, preterm females had significantly higher InMfs compared with full-term females (P < 0.001), whereas preterm males were found to have significantly lower InMfs than preterm females (P = 0.005). Regression analyses also demonstrate a s ignificant relationship between InMf and gestational age for preterm female s that does not exist for preterm males. These results demonstrate the gend er-specific association between Mf and age in humans.