oa A rare case of de novo mosaic deletion 18p/ isochromosome 18q syndrome : Report and review of the literature

Monosomy 18p syndrome is a rare, 50-year-old chromosomal disorder with varying phenotypical clinical manifestations. Dysmorphism, growth delay, delayed speech and mental retardation are a few common features observed. The cytogenetic findings also vary in each case. It may occur just as a pure deletion of entire 18p arm or as deletion of partial 18p arm, if involved in a translocation with other chromosomes. It may either occur solely or along with structurally altered other chromosome 18, as a ring or an isochromosome. Studies suggest genotype-phenotype correlation, in relation to the locus of chromosomal breakpoint present on 18p with its clinical presentation. Often, the clinical presentation of this syndrome overlaps with other syndromes. Hence, establishing a cytogentic diagnosis is very crucial for precise management and follow up. Although there are earlier reports of cases with deletion of 18p alone, very few cases are reported with additional abnormalities particularly i(18q). There was only a single case report of a mosaic with del 18p/i(18q) three decades ago. We present here, the second report of a rare case with de novo mosaic - deletion 18p with isochromosome 18q, in a boy born to a consanguineous Arabic Omani couple with review of the literature.