Model Computes Genetic Test, Family History Predictive Value

Anne Wojcicki (23andMe Inc.)

Researchers at the genetic testing company 23andMe in Mountain View, California devised a mathematical model that shows the relative value of personal family history and genetic tests in assessing risk of contracting various conditions and disorders. The results of their research appear in the journal PLOS Genetics.

The study aimed to compare family health histories and genetic testing to assess risk for a number of common and less common conditions: coronary artery and heart diseases, type 1 and 2 diabetes, prostate cancer, Alzheimer’s disease, breast cancer, lung cancer, Crohn’s and celiac disease, ovarian cancer, melanoma, bipolar disease, and schizophrenia. The team used quantitative genetic theory to develop a mathematical model to test the comparative value of each method in predicting the disease frequency and heritability of each condition.

The findings suggest that neither method alone was always the better predictor of these conditions. The analysis indicated family history is most useful for highly common, heritable conditions and for single-gene (Mendelian) disorders where the specific genetic cause is not yet known. Family history seems particularly helpful with common disorders such as coronary artery disease that may have many contributing genetic and environmental factors.

Genetic testing, in this case tests based on single nucleotide polymorphisms (SNPs), have more value for less common diseases with weak genetic associations, such as Crohn’s disease, where family history accounts for a small percentage of disease heritability. When family histories are  less informative, genetic testing can show the genetic variants that may put an individual at a higher or lower risk for the condition.

SNPs are DNA sequences that occur when a single molecule of DNA in the genome differs between individuals or paired chromosomes in an individual. SNPs can determine biological variations among individuals causing differences in the mix of proteins specified in one’s genes. Those differences can result in a variety of traits such as disease susceptibility and the response to drugs.

The researchers say this study is the first broad comparison of family history and SNP–based methods across a wide range of health conditions, with the results suggesting both approaches, when used together, can provide benefits to an individual. “Both family history and genetics are important tools for assessing an individual’s risk for disease,” says 23andMe’s CEO Anne Wojcicki (pictured at top). “We believe it will become increasingly important for individuals and physicians to know both family history and genetic profile to provide optimal health care.”

Read more:

• Faster Whole Genome Sequencing Developed for Infants
• 23andMe Opens Application Interface to Outside Developers
• Alzheimer’s Biomarker Project to Gain Whole Genome Data
• Cleveland Clinic, 23andMe Partner on Parkinson’s Database

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