While DNA methylation is often associated with reduced gene expression, other chromatin modifications (histone acetylation) are often correlated with increased transcriptional activity. The downstream effect of histone trimethylation is dependent on the specific nucleotide residue involved. In addition, it is important to remember that overexpression of genes can be disruptive. For instance, over-expression of cardiac-specific genes following early gestational alcohol exposure was determined to be regulated through Histone 3 acetylation (Zhang et al., 2014), and thought to contribute to the development of heart malformations and congenital heart disease (CHD). In vitro analysis of cardiac progenitor cells reached a similar conclusion that altered Histone 3 acetylation patterns following alcohol exposure could lead to CHD. In children with FASD, certain types of heart defects are associated with exposure, including those affecting the ventricles and arteries (Burd et al., 2007; Yang et al., 2015).
