*2.5.1 13q deletion syndrome*

Children with this syndrome may present with characteristic dysmorphic features, developmental delay, and intellectual disability. Interstitial chromosome deletion or translocation of region 13q14 was found in approximately 6% of patients with RB [67]. The larger the size of chromosomal deletion, the more severe the associations. Dysmorphic facial features include high and broad forehead, short nose, prominent philtrum, and a thick everted lower lip [67]. Karyotype or chromosomal microarray is usually performed to detect chromosomal deletions, translocations, and copy number alteration [68].
