HETEROZYGOUS MICRODELETION 2q31.2-q33.1 IN A CHILD WITH CONGENITAL FLEXOR CONTRACTURES

Abstract

Thousands of babies are born every year with errors in the structure of their chromosomes. An excess or absence of certain chromosomal material leads to a chromosomal imbalance that disrupts the normal development of the body. Until recently, small microdeletions of the long arm of chromosome 2, causing multiple malformations, dysmorphia and/or mental retardation, remained undetected due to the lack of available molecular genetic diagnostics. Diagnosis was based on the general clinical picture and the ability to detect chromosomal abnormalities using standard karyotype analysis or specific tests such as fluorescence in situ hybridization. Over the past decade, the development of new genomic technologies has made it possible to conduct a more comprehensive, unbiased detection of microdeletions in the entire human genome. The ability to rapidly analyze large cohorts using chromosomal microarrays (arrayCGH) and next-generation sequencing (NGS) has led to the rapid discovery of new microdeletions and microduplications that are clinically relevant (7).

According to the literature, interstitial deletions of chromosome 2q31 have been described in more than 30 patients. Deletions of chromosome 2q31 varied in size and location and were associated with variable clinical manifestations. The clinical phenotype of this syndrome is characterized by limb abnormalities: monodactyly, ectrodactyly, brachydactyly, syndactyly to camptodactyly (4). Additional abnormalities of internal organs may be present: heart defects, vision abnormalities (2). The following craniofacial dysmorphisms are characteristic: microcephaly, anti-Mongoloid cut of the eyes, long and flat philtrum, micrognathia, dysplastic and low-set ears (3). For deletion 2q31.1-q31.2. characteristic oligodactyly, ectrodactyly, brachydactyly and clinodactyly with syndactyly, which are associated with the deletion of the HOXD cluster. Some patients may have microcephaly and growth retardation. Patients with a 2q32-q33.1 deletion have mental retardation, learning disabilities, growth retardation, thin and sparse hair, feeding difficulties, cleft lip and/or palate, and multiple dysmorphic features. SATB2 haploinsufficiency has been suggested to be responsible for most of these disorders (1, 5, 6).

There are several publications about interstitial deletions in the long arm of chromosome 2, but we have not found in the specialized literature a description of a case of microdeletion 2q31.2.q33.1.