A Distinctive Type of Mosaic Variegated Aneuploidy: Case Report and Review of the Literature

Abstract

Mosaic variegated aneuploidy (MVA) is an autosomal recessive disorder characterized by mosaic aneuploidies, predominantly trisomies, involving multiple different chromosomes and tissues. The proportion of aneuploid cells varies, and most patients present with intrauterine growth delay, microcephaly, and a broad spectrum of congenital abnormalities. We report a patient with a distinctive type of MVA discovered in bone marrow (BM) when she was 3-month-old due to neutropenia and hypocellular bone marrow. She was followed up for more than 20 years, and different trisomic cells were repeatedly discovered in different tissues, whereas her clinical picture has never been severe. The main sign remained intermittent neutropenia, not cyclic and often not too severe, occasionally with anemia and thrombocytopenia. Retromicrognathia was the only dysmorphic sign. Unlike other patients with MVA, the trisomies in all tissues involved almost invariably chromosomes 18 and 19. Therefore, the peculiarities of our patient were the clinical and the atypical cytogenetic pictures. Nevertheless, we looked for mutations in the seven causative genes of the known types of MVA, but the results were negative. Then, we analyzed the entire exome to find out other possible causing mutations, but also this attempt failed to discover a possible cause of this distinctive form of MVA.

Keywords: exome sequencing; gene variants; intermittent neutropenia; mosaic variegated aneuploidy (MVA); trisomies 18 and 19.