Genes and non-mendelian diseases: dealing with complexity

Area of Science:

• Medical Genetics
• Genomics
• Complex Disease Research

Background:

• Early medical genetics (1980-2000) successfully identified genes for Mendelian disorders.
• Research in the 1990s struggled to find genes for complex diseases like autism, despite their known genetic basis.
• Significant advancements in genomics and analytical methods since 2000 enabled Genome-Wide Association Studies (GWAS).

Purpose of the Study:

• To review the progress and challenges in identifying genes for complex genetic disorders.
• To highlight the specific difficulties encountered in autism genetics research.
• To discuss the translation of genetic findings into clinical utility.

Main Methods:

• Review of historical successes in Mendelian genetics.
• Analysis of the limitations of 1990s gene discovery for common disorders.
• Application of Genome-Wide Association Study (GWAS) approach for complex conditions.
• Examination of challenges in autism gene identification and genetic testing.

Main Results:

• Thousands of Mendelian genetic conditions have had their causative genes identified.
• GWAS have improved the identification of genes influencing complex disease risk.
• Significant challenges persist, including the 'missing heritability' problem and clinical translation difficulties.
• Autism genetics remains complex due to numerous genes and potential heterogeneity, impeding valid genetic test development.

Conclusions:

• While Mendelian genetics has seen great success, complex diseases like autism present ongoing genetic research challenges.
• The 'missing heritability' and clinical utility of genetic tests for complex conditions require further investigation.
• The heterogeneity and polygenic nature of autism complicate gene discovery and the development of reliable genetic diagnostics.