Genetic Testing for Hair Loss: What 23andMe and Polygenic Scores Actually Predict

Direct-to-consumer genetic testing services including 23andMe report 'baldness likelihood' based on single nucleotide polymorphisms (SNPs) associated with androgenetic alopecia in genome-wide association studies. The strongest single signal is the X-linked AR gene region, with the SNP rs6152 being the most-cited single marker. Carrying the risk allele is associated with roughly 2-fold higher odds of significant pattern hair loss compared to non-carriers.

The catch: AR is only one of approximately 200 loci with credible association evidence for androgenetic alopecia. The full polygenic risk picture explains roughly 25% of heritability, meaningful but far from deterministic. A high polygenic risk score means elevated probability of pattern hair loss, not certainty. A low score means reduced probability, not protection. Many men with low risk scores still develop significant hair loss, and many high-score individuals retain dense hair into their 70s.

The practical value of genetic testing for hair loss is currently limited. Family history alone predicts about as well as polygenic scores in most cohorts. Where genetic information may eventually add value is in pharmacogenomics, predicting drug response. SULT1A1 variants affect minoxidil response. 5-alpha reductase isoform polymorphisms may affect finasteride response. As these clinical applications mature, genetic testing may move from cosmetic curiosity to treatment guidance. The current generation of consumer reports is mostly entertainment.