Abstract
Background The 22q11.2 deletion syndrome (22q11.2DS) is the most common form of deletion disorder in humans. Low copy repeats flanking the 22q11.2 region confers a substrate for nonallelic homologous recombination (NAHR) events leading to rearrangements which have been reported to be associated with highly variable and expansive phenotypes. The 22q11.2DS is reported as the most common genetic cause of congenital heart defects (CHDs). Methods A total of 42 patients with congenital heart defects, as confirmed by echocardiography, were recruited. Genetic molecular analysis using a fluorescence in situ hybridization (FISH) technique was conducted as part of routine 22q11.2DS screening, followed by multiplex ligation-dependent probe amplification (MLPA), which serves as a confirmatory test. Results Two of the 42 CHD cases (4.76%) indicated the presence of 22q11.2DS, and interestingly, both cases have conotruncal heart defects. In terms of concordance of techniques used, MLPA is superior since it can detect deletions within the 22q11.2 locus and outside of the typically deleted region (TDR) as well as duplications. Conclusion The incidence of 22q11.2DS among patients with CHD in the east coast of Malaysia is 0.047. MLPA is a scalable and affordable alternative molecular diagnostic method in the screening of 22q11.2DS and can be routinely applied for the diagnosis of deletion syndromes.
Highlights
The 22q11.2 deletion syndrome (22q11.2DS) is the most common genetic disorder caused by deletions of chromosome 22, at the q11.2 locus [1]
The research project was approved by the Research and Ethics Committee, School of Medical Sciences, Universiti Sains Malaysia (USM) Health Campus (USMKK/PPP/JEPeM [252.3(13)]), and the Ministry of Health Malaysia (KKM/NIHSEC/BOO-2/2/2/P13-147) which complies with the Declaration of Helsinki
congenital heart defects (CHDs) patients admitted to Hospital Universiti Sains Malaysia (HUSM), which serves as the main tertiary cardiac referral centre in the east coast region of Peninsular Malaysia from January 2013 to November 2014, were recruited (n = 42)
Summary
The 22q11.2 deletion syndrome (22q11.2DS) is the most common genetic disorder caused by deletions of chromosome 22, at the q11.2 locus [1]. 97% of patients with 22q11.2DS were reported to harbour the 3 Mb deletion of DNA, causing a haploinsufficiency in about 30-40 genes within the locus [3, 4]. In terms of congenital heart defects (CHDs), the 22q11.2DS has been reported as a common genetic cause, contributing to approximately 1.9% of CHDs at birth [4]. The 22q11.2DS is reported as the most common genetic cause of congenital heart defects (CHDs). MLPA is a scalable and affordable alternative molecular diagnostic method in the screening of 22q11.2DS and can be routinely applied for the diagnosis of deletion syndromes
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