A novel microdeletion syndrome at 9q21.13 characterised by mental retardation, speech delay, epilepsy and characteristic facial features.

The increased use of array-CGH and SNP-arrays for genetic diagnosis has led to the identification of new microdeletion/microduplication syndromes and enabled genotype-phenotype correlations to be made. In this study, nine patients with 9q21 deletions were investigated and compared with four previously Decipher reported patients. Genotype-phenotype comparisons of 13 patients revealed several common major characteristics including significant developmental delay, epilepsy, neuro-behavioural disorders and recognizable facial features including hypertelorism, feature-less philtrum, and a thin upper lip. The molecular investigation identified deletions with different breakpoints and of variable lengths, but the 750 kb smallest overlapping deleted region includes four genes. Among these genes, RORB is a strong candidate for a neurological phenotype. To our knowledge, this is the first published report of 9q21 microdeletions and our observations strongly suggest that these deletions are responsible for a new genetic syndrome characterised by mental retardation with speech delay, epilepsy, autistic behaviour and moderate facial dysmorphy.