X-monosomy is a form of Turner syndrome (TS) in which an entire X chromosome is 
missing. It is usually assumed that neuropsychological deficits in females with 
TS result from insufficient dosage of gene products from alleles on the sex 
chromosomes. If so, then parental origin of the single X chromosome should be 
immaterial. However, if there are imprinted genes on the X chromosome affecting 
brain development, neuropsychological development will depend on the parental 
origin of the single X chromosome. We contrasted verbal 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 any impairment on immediate story 
recall; if anything, performance was above control levels. Groups did not differ 
on a measure of delayed recall. However, when delayed recall was considered 
after adjusting for level of immediate recall, 45,X(m) females showed enhanced 
verbal forgetting relative to controls over a delay. On the Rey figure, both 
groups were poor at copying the figure, but, after adjusting scores for initial 
copy score and strategy, only the 45,X(p) females showed disproportionate 
forgetting relative to controls. We propose there may be one or more imprinted 
genes on the X chromosome that affect the development of lateralised brain 
regions important for memory function.