Autosomal fragile site at 2q13 in a proband with mental retardation.

Folate sensitive fragile site on chromosome 2q13 was detected in a female proband with mild hypertrichosis, negativism, speech disorder, and severe mental retardation. The same chromosomal aberration was also detected in her mother with normal phenotype. Spontaneous expression of fragile site on 2q13 was also observed.