Case Report: Intellectual disability and borderline intellectual functioning in two sisters with a 12p11.22 loss

In this study, we report two sibling patients who were 5 years 9 months old and 3 years 3 months old and presented to the hospital due to developmental delay. Clinical assessment and chromosomal microarray analysis were performed. The patients were diagnosed with mild intellectual disability (ID) and borderline intellectual functioning (BIF). Genetic analysis identified a loss of 12p11.22, including the OVCH1-AS1, OVCH1, and TMTC1 genes, which was the only variant that occurred in both sisters. Identical variants were found in their father with probable BIF. Neither patient presented any brain structural abnormalities or dysmorphism, and no exogenous factors or parenting problems were reported. Thus, loss of 12p11.22 may be associated with our patients’ cognitive impairment. The OVCH1, OVCH1-AS1 and TMTC1 variants identified in this study are the most likely disease-causing genes in the sisters. Our findings may expand as yet limited knowledge on mild ID and BIF causative variants, which would further support the diagnosis even if the severity is mild.
Source: Frontiers in Genetics - Category: Genetics & Stem Cells Source Type: research