Genotype-phenotype correlation in congenital heart disease

Genome-wide association studies of structural birth defects: A review and commentary

BACKGROUND

While there is strong evidence that genetic risk factors play an important role in the etiologies of structural birth defects, compared to other diseases, there have been relatively few genome-wide association studies (GWAS) of these conditions. We reviewed the current landscape of GWAS conducted for birth defects, noting novel insights, and future directions.

METHODS

This article reviews the literature with regard to GWAS of structural birth defects. Key defects included in this review include oral clefts, congenital heart defects (CHDs), biliary atresia, pyloric stenosis, hypospadias, craniosynostosis, and clubfoot. Additionally, other issues related to GWAS are considered, including the assessment of polygenic risk scores and issues related to genetic ancestry, as well as utilizing genome-wide single nucleotide polymorphism array data to evaluate gene-environment interactions and Mendelian randomization.

RESULTS

For some birth defects, including oral clefts and CHDs, several novel susceptibility loci have been identified and replicated through GWAS, including 8q24 for oral clefts, DGKK for hypospadias, and 4p16 for CHDs. Relatively common birth defects for which there are currently no published GWAS include neural tube defects, anotia/microtia, anophthalmia/microphthalmia, gastroschisis, and omphalocele.

CONCLUSIONS

Overall, GWAS have been successful in identifying several novel susceptibility genes and genomic regions for structural birth defects. These findings have provided new insights into the etiologies of these phenotypes. However, GWAS have been underutilized for understanding the genetic etiologies of several birth defects.

Implications of genetic testing for sudden cardiac death syndrome

The completion of the Human Genome Project in 2003 is shifting the focus of modern health care from disease management based on clinical signs to genomic-based treatment and prevention. Nurses at all levels of practice are going to increasingly come under pressure to deliver evidence-based, competent care to families undergoing genetic testing for hereditary conditions (Skirton and Barnes, 2005). A new chapter added to the National Service Framework for Coronary Heart Disease in 2005 raised awareness of the genetic basis of up to 400 sudden cardiac deaths that occur every year in the UK (Department of Health, 2005). This article addresses some of the clinical and ethical implications for nurses caring for families who may be at risk of an inherited sudden cardiac death syndrome. Nursing practice implications are discussed, concluding that more research is needed to explore how family members cope with genetic information which will shape the provision of future genetic healthcare.