A rare unbalanced translocation 1;18 in a child with epilepsy, mild dysmorphology and mental retardation.

A syndrome due to deletion of distal long arm of 1q was delineated by several groups. Up to now different terminal deletions 1q are described often clinically resulting in diagnosed mental retardation syndromes. We report on a 7-year-old male with distal monosomy 1q and additional genetic material on the short arm of chromosome 18. As expected, cytogenetic studies of the infant and his mother showed that the altered regions result from an unbalanced translocation of part of the long arm of chromosome 1. Comparison of our patient's data with those previously reported reveals neurological similarities but an unique genotype-phenotype correlation. The importance of a following better molecular characterization through array comparative genomic hybridization and especially the DNA sequence analysis around its breakpoints are discussed.