m<i>ir152</i> hypomethylation as a mechanism for non-syndromic cleft lip and palate

Non-syndromic cleft lip with or without cleft palate (NSCLP), the most common human craniofacial malformation, is a complex disorder given its genetic heterogeneity and multifactorial component revealed by genetic, epidemiological, and epigenetic findings. Epigenetic variations associated with NSCLP have been identified; however, functional investigation has been limited. Here, we combined a reanalysis of NSCLP methylome data with genetic analysis and used both <i>in vitro</i> and <i>in vivo</i> approaches to dissect the functional effects of epigenetic changes. We found a region in <i>mir152</i> that is frequently hypomethylated in NSCLP cohorts (21–26%), leading to <i>mir152</i> overexpression. <i>mir152</i> overexpression in human neural crest cells led to downregulation of spliceosomal, ribosomal, and adherens junction genes. <i>In vivo</i> analysis using zebrafish embryos revealed that <i>mir152</i> upregulation leads to craniofacial cartilage impairment. Also, we suggest that zebrafish embryonic hypoxia leads to <i>mir152</i> upregulation combined with <i>mir152</i> hypomethylation and also analogous palatal alterations. We therefore propose that <i>mir152</i> hypomethylation, potentially induced by hypoxia in early development, is a novel and frequent predisposing factor to NSCLP.