Policy Watch: Assembly Bill 425 – Medi-Cal Pharmacogenomics

May 6, 2023 | Policy

By Chantelle Schenning and Megan Boyd

Pharmacogenomics is the science of how an individual’s genetic makeup impacts the way they process medications, having huge impacts on whether the medication is effective, helps, harms, or potentially kills the patient taking it. 99% of people harbor at least one genetic factor that affects the way they respond to medication, meaning the potential for people to be on the wrong medication or wrong dose is unfortunately very high. This staggering prevalence contributes to the frightening fact that adverse drug events (ADEs) — harms to an individual because of a medication they are taking — are the fourth leading cause of death in the United States. In California, one person dies every 16 minutes from an ADE.  A recent Lancet study from Europe that followed 7,000 patients saw a 30% reduction in ADEs by using pharmacogenomic testing within just 12 weeks.

Chantelle Schenning

While nearly everyone has a pharmacogenomic variant, harms resulting from medications are not distributed evenly across our population. Women are twice as likely to experience an ADE compared to men, and Black patients are nearly 1.4x as likely to experience an ADE compared to white patients. Other people of color are also more likely to experience ADEs at higher rates. This is, in part, due to a disproportionate participation of males of European descent in early clinical trials used to determine the efficacy of medications and the “standard” dose of those drugs. AB 425 offers one solution to mitigate the harms of the past, and targets the populations most likely to experience ADEs — Californians within the Medi-Cal Program.


In February 2023, Assemblyman Alvarez introduced Assembly Bill 425, which would mandate coverage of pharmacogenomic testing (PGx) within the Medi-Cal Program. There are currently two co-authors — Assemblywoman Aguiar-Curry and Assemblyman Rodriguez — and additional Assemblymembers are expected to add their names to the list. 

Who should pay attention?
Anyone serving Medi-Cal patients. Pharmacogenomic testing informs medication management across many different specialties (including mental health, oncology, pain management, cardiology, etc). Medicare and many commercial payers already cover PGx testing for those patients.

Megan Boyd

Pharmacogenomic testing reduces health inequities, improves patient safety, and advances patient outcomes while optimizing organization’s financial performance. By using pharmacogenomics in medication management, health systems have reported 52% reduction in readmissions and 42% reduction in emergency department visits, saving $4,382 per patient. 

How to Take Action and Learn More?
Healthcare leaders looking to implement solutions to reduce healthcare costs, improve patient outcomes, and deliver equitable care for all should consider supporting AB 425. Leaders looking to show their support can sign on as an individual and/or as an organization here. Additionally, healthcare organizations can submit their own letters of support through the California Legislature Advocates Portal

If you want to learn more about pharmacogenomics, please feel free to contact Chantelle Schenning at chantelle.schenning@invitae.com

Disclaimer: Chantelle and Megan are employees of Invitae, a diagnostic laboratory that provides PGx Testing.