Constitutional Partial Proximal Trisomy 14q11.2 to 14q21: Two New Moroccan Cases and Review of the Literature

Small supernumerary marker chromosomes (sSMCs), a major problem in clinical cytogenetics, are too small to be characterized for their chromosomal origin by cytogenetic banding techniques. Most sSMCs have not yet been correlated with a specific clinical syndrome, and genotype-phenotype correlation in sSMC-patients is still in major parts under development. In this paper we report two new Moroccan cases with a polymalformative syndrome, in which we identified similar but not identical sSMCs derived from chromosome 14; in one case a +del(14)(q21.1) and in the other a +del(14)(q21.2). To the best of our knowledge, such de novo proximal partial trisomies 14 have previously been reported in only two patients. A comparison of the clinical features of these four cases revealed an expanded clinical spectrum related to this chromosomal aberration; as one case from the literature was associated with gonadal tumor development, similar cases, including the ones here reported, need to be followed up for this condition.