Verbal learning and memory among heterozygous fragile X females.

In this paper we report the results of a brief examination of verbal learning and memory in 20 heterozygous fragile X [fra(X)] positive females and in 2 control groups of 20 subjects each. One control group was composed of fra(X)-negative mothers (obligate carriers) and sisters of male probands with fra(X) syndrome, while the other consisted of 14 head injured and 6 learning disabled females. Intellectual functioning was assessed by means of the Wechsler scales, and learning was assessed by several different clinical memory tests. Significant differences were found between groups on measures of short-term memory and learning efficiency. Groups did not differ on measures of cued recall or delayed recall. The findings are consistent with other data and suggest the possibility that central information processing and/or specific encoding processes are defective in persons with fra(X).