Mosaic trisomy 14 is associated with impaired intellectual functioning, although no study has examined the cognitive-behavioral profile associated with the syndrome. This study provides the first case description of the cognitive-behavioral phenotype associated with mosaic trisomy 14 by contrasting the performance an adolescent female (T14) with a group of females with Down syndrome (DS; n=9). T14 performed below age expectations on most direct assessments and demonstrated weaknesses relative to the DS group on aspects of language, adaptive functioning, and executive functioning. T14 also demonstrated strengths in delayed visual recall and social skills relative to the DS group.
Keywords: Cognition; genetic disorder; intellectual disability; neurodevelopment.