Introduction
In recent years, chromosomal microarray analysis (CMA) allowed the
identification of a growing number of chromosomal imbalances within the
human genome (Wolfe, 2018). These copy number variations (CNVs, defined
as a greater than 1 kb segment of DNA that has variable copy number as
compared to normal reference genome) include deletions and duplications
(Yu, 2012), and involve single or multiple genes (Wolfe, 2018). CNVs may
be either benign, or associated with diseases
(Yu, 2012). Some regions of the genome are flanked by highly homologous
sequences (segmental duplications, SDs, also known as low copy repeats)
(Rudd, 2009). They are prone to mismatching and, then, to recurrent
CNVs, some of which cause clinically recognizable phenotypes (i.e.,
Angelman, Prader-Willi, Smith-Magenis and Williams-Beuren syndromes)
(Wolfe, 2018; Hladilkowa, 2015). The 2q13 region contains clusters of
such SDs, which facilitate recurrent deletions and/or duplications.
These imbalances are less described than those affecting other
chromosomes (Hladilkowa, 2015). A recurrent pathogenic 1.71 Mb
microdeletion is reported to date in around 50 patients (Wolfe, 2018).
Their clinical phenotype is variable for the occurrence of mild (in the
majority of cases) dysmorphic features, macro- or microcephaly,
neurodevelopmental delay/behavior disorder (including hypotonia,
impairment in fine and global motor skills, autism spectrum disorder,
attention deficit and hyperactivity disorder), as well as congenital
heart disease (CHD, the most frequent anomaly) and other congenital
defects (i.e. scoliosis, renal/genital malformations) (Guivarch, 2018).
Hereby, we describe an additional newborn with craniofacial
dysmorphisms, CHD, hypotonia and a 2q13 deletion of 1.7 Mb, whose
diagnosis is consistent with 2q13 microdeletion syndrome. This new
neonatal case report may provide additional genotypic and clinical data,
as well as further insights into the possible biological and molecular
bases of the 2q13 microdeletion syndrome.