Essential in genetic etiology of congenital heart diseases

Abstract

Congenital heart disease (CHD) represent another unsolved problem of the present, although new techniques of exploration like fluorescence in situ hybridization (FISH), high resolution array-comparative genomic hybridization (array-CGH), single nucleotide polymorphisms (SNPs), comparative genomic hybridization (CGH) and spectralkaryotyping (SKY) explain some genetic mechanisms implied in the genesis of this pathology. However, there are many unresolved issues. Structural modifications of chromosomes by duplication and also by deletion determine variable phenotypes depending on the altered structural site. Given that, the genetic defect affects only one gene or more but determines repercussions over the cardiac anatomy or/and other non-cardiac systems, as a result the phenotype can be syndromic or nonsyndromic. The raised or low number of chromosomes was the first explanation for CHD. Trisomy 21 (Down's syndrome), 18 (Edward's syndrome), 13 (Patau's syndrome), monosomy X (Turner's syndrome), deletion at chromosome 7q11.23 and 22q11.2, multiple gene mutations, are the most frequent chromosomal or sub-chromosomal destructuring along with syndromic phenotype. Copy number variations (CNVs) is defined as subchromosomal mechanism that by deletion or multiplication produces in general nonsyndromic phenotype. Transcription factors T-Box protein 5 (TBX5), mNK2 Homeobox 5 (NKX2.5), GATA-binding protein 4 (GATA4) are specific proteins that sending information from DNA to RNA messenger can undergo structural denaturations and if this happens these proteins cannot send correct messages resulting in alteration of the normal chain of cardiogenesis. Combination between these mechanisms and unitary action produce CHD in different forms, syndromic or nonsyndromic.