Pure 16q21q22.1 deletion in a complex rearrangement possibly caused by a chromothripsis event

Partial monosomies of chromosome 16q are rare and overlapping effects from complex chromosomal rearrangements often hamper genotype-phenotype correlations for such imbalances. Here, we report the clinical features of an isolated partial monosomy 16q21q22.1 in a boy with a complex de novo rearrangement possibly resulting from a chromothripsis event.

The patient presented with low birth weight, microcephaly, developmental delay, facial dysmorphisms, short stature, dysmorphic ears and cardiopathy. Standard and molecular cytogenetics showed a complex rearrangement characterised by a pericentromeric inversion in one of chromosomes 12 and an inverted insertional translocation of the 12q14q21.1 region, from the rearranged chromosome 12, into the q21q22.1 tract of a chromosome 16. Array-CGH analysis unravelled a partial 16q21q22.1 monosomy, localised in the rearranged chromosome 16.

The comparison of the present case to other 16q21q22 monosomies contributed to narrow down the critical region for cardiac anomalies in the 16q22 deletion syndrome. However, more cases, well characterised both for phenotypic signs and genomic details, are needed to further restrict candidate regions for phenotypic signs in 16q deletions. The present case also provided evidence that a very complex rearrangement, possibly caused by a chromothripsis event, might be hidden behind a classical phenotype that is specific for a syndrome.