Distinctive patterns of memory function in subgroups of females with Turner syndrome: evidence for imprinted loci on the X-chromosome affecting neurodevelopment

X-monosomy is a form of Turner syndrome (TS) in which an entire X chromosom e is missing. It is usually assumed that neuropsychological deficits in fem ales with TS result from insufficient dosage of gene products from alleles on the sex chromosomes. If so, then parental origin of the single X chromos ome should be immaterial. However, if there are imprinted genes on the X ch romosome affecting brain development, neuropsychological development will d epend on the parental origin of the single X chromosome. We contrasted verb al and visuospatial memory in females with a single paternal X chromosome ( 45,X-p) and those with a single maternal X (45,X-m). Neither group showed a lly impairment on immediate story recall; if anything, performances was abo ve control levels. Groups did not differ on a measure of delayed recall. Ho wever, when delayed recall was considered after adjusting for level of imme diate recall, 45,X-m females showed enhanced verbal forgetting relative to controls over a delay. On the Ray figure, both groups were poor at copying the figure, but, after adjusting scores for initial copy score and strategy , only the 45,X-p,XP females showed disproportionate forgetting relative to controls. We propose there may be one or mere imprinted genes on the X chr omosome that affect the development of lateralised brain regions important for memory function. (C) 2000 Elsevier Science Ltd. All rights reserved.