Familial hypercholesterolemia (FH) strikes one out of every 200-250 individuals. Early diagnosis is critical for administering needed treatments and aggressive interventions to reduce lifetime risks. Yet the disorder is often underdiagnosed, and optimal methods for detecting it are still under investigation, Heather Lindsey writes in the August issue of Clinical Laboratory News.
Age is an important variable in detecting FH, as environmental factors such as poor eating and exercise habits raise already high cholesterol levels as people get older. “While a simple and affordable universal cholesterol blood test identifies FH in children, older family members—who also may have the condition—typically need a more expensive genetic test,” Lindsey’s article explains.
Investigators have considered different types of screening approaches in both children and adults. Newborn screening is an inexpensive alternative that would deliver clear results. Universal cholesterol screening in children ages 9 to 11 has generated the most interest in the United States, but faces some obstacles.
National entities have issued conflicting evidence and recommendations on the benefits of screening for FH in children. Insufficient long-term data exists to support screening in children and adolescents, and as some experts point out, it would be an expensive proposition to conduct studies on the long-term effects of statins on children.
Clinicians also don’t have the luxury of waiting decades for outcomes data to guide treatment decisions, when high-risk patients with low-density lipoprotein cholesterol need immediate attention and treatment, according to Michael Murray, MD, director of clinical genomics at Geisinger Medical Center in Danville, Pennsylvania.
Genetic tests for FH show promise in yielding highly accurate results compared with other tests. The process of conducting genomic sequencing to detect FH mutations is somewhat complicated, however, and is also costly.
Cascade screening, which involves testing first-degree family members upon the identification of an index case, shows promise as a universal testing method for FH. A study in the New England Journal of Medicine that screened nearly 11,000 children for FH during routine immunization visits managed to identify a number of FH cases among children and parents.
The one caveat of cascade testing is it “implies that you have a proband. Family screening often only goes so far since some people don’t know who their relatives are or contacting them can be difficult. So, you always have to be finding new probands,” says Paul Hopkins, MD, MSPH, FNLA, professor of internal medicine in the cardiovascular genetics research program at the University of Utah School of Medicine in Salt Lake City.
While expensive, the ability of genetic screening to detect FH mutations in adults could help identify individuals at especially high risk for heart attack and stroke.
Pick up the August issue of CLN to get additional details on the benefits and drawbacks of FH screening methods.