DID YOU KNOW...
Exploring Familial Hypercholesterolemia (FH)
Which is Largely Undiagnosed and Places
Those with FH At High Risk of Death Due to Cardiovascular Disease?

By: John Sawdon Director of Education & Special Projects, Cardiac Health Foundation of Canada

Familial Hypercholesterolemia is a genetic disorder characterised by very high plasma levels of low density lipoprotein cholesterol (LDL-C) which increases cardiovascular risk by up to 20 times and causes early onset of cardiovascular disease. FH is the most common single gene disorder leading to cardiovascular disease. Often FH is not recognized until the individual has a cardiovascular event. If identified early and treated, life expectancy can be prolonged. If left untreated men will develop cardiovascular disease in their thirties or early forties and women approximately ten years later. The number of cases of Familial Hypercholesterolemia is approximately 1 in 500 with French Canadians having a higher incidence rate at 1 in 275. Based on these numbers it is projected that 83,500 individuals in Canada have Familial Hypercholesterolemia. (1)

Most Familial Hypercholesterolemia patients are undiagnosed due to inconsistent screening practises and a lack of awareness regarding diagnosis. The Canadian Cardiovascular Society recommended that the diagnosis of FH should rely on the Simon Broom Registry or the Dutch Lipid Clinic network criteria. (2)

A) Simon Broom Registry Criteria

  • Total cholesterol >7.5mmol/L (for adults) or >6.7mmol/L (for children under 16) LDL-C low density lipoprotein cholesterol >4.9mmol/L (adults) or >4.0 mmol/L (for child under 16)
  • A nodule or plaque on the tendon on the patient or any of the patients first or second degree relatives
  • DNA based evidence of mutation in LDLR or other FH-related gene in the patient
  • Family history of myocardial infarction before age of 50 years in first or second degree relative or 60 years of age for first degree relative
  • Family history of total cholesterol >7.5mmol/L in any first or second degree relative

B) Dutch Lipid Clinic Network

  • First Degree relative with premature cardiovascular disease or LDL-C >95 percentile, or personal history of premature peripheral or cerebrovascular disease or LDL-C between 155 mg/dL and 189mg/dL
  • First degree relative with nodule lipd deposits on the tendon, cornea arcus, or First degree relative child less than 18years with LDL-C in the 95 percentile or personal history of coronary artery disease
  • LDL-C between 4.91(190mg/dL) and 6.44(249mg/dL)
  • Presence of corneal arcus in patient younger than 45 years of age
  • LDL-C between 6.46( 250 mg/dL) and 8.51 mmol/L( 329mg/dL)
  • Presence of tendon lipid nodule
  • LDL-C >8.53 mmol/L(330mg/dL) or mutation of LDLR gene

Figure 1

Figure 1 above reflects a single inherited gene compared to a double inherited gene in Familial Hypercholesterolemia. In Figure 2 below reflects the passing on of this gene when considering first degree relatives and second degree relatives that are mentioned in diagnosing FH using both the Simon Broom Registry criteria and the Dutch Lipid Clinic Network criteria.


Figure 2 the Familial Hypercholesterolemia Family Tree

Because Familial Hypercholesterolemia is so difficult to diagnose and treat until someone has experienced a cardiac event, individuals who have family members with high LDL-C readings or who have had a myocardial infarction at a young age are encouraged to both register with FH Canada and engage in pharmaceutical and lifestyle therapy. The aim of the Registry is to “improve the detection and management of individuals and families with FH and other severe lipid disorders in Canada” and “ to lower their high blood cholesterol and prevent early cardiovascular disease”. The Benefits of participating in the registry include:

  • Early diagnosis of Familial Hypercholesterolemia for the entire family
  • Better management of high cholesterol levels
  • Prevention of Heart Disease in family members with FH
  • Access to new medications as part of clinical trials(3)

To find out more about the registry and how it might benefit you and your family go to www.fhcanada.net or call Isabelle Ruel PhD at 1-514-934-1934 extension 34852.


Figure 3 Chart looks at Bad Cholesterol or LDL-C levels and Good Cholesterol HDL-C and Triglycerides

When comparing the levels of cholesterol in the blood to levels of those diagnosed with Familial Hypercholesterolemia we find extremely high levels of Bad Cholesterol present that leads to atherosclerosis and subsequent myocardial infarction or heart attacks at a young age FH is an inherited disorder that leads to aggressive and premature cardiovascular disease. This includes heart attacks, strokes and narrowing of heart valves.. If FH is untreated the estimated risk for a coronary event (4) is 50% for men by 50 years of age and 30% for women by age 60 years.

This article is intended to create awareness of Familial Hypercholesterolemia. Although we will discuss new treatment options in combating early cardiovascular disease during our next segment, the current treatment options include substantial lowering of LDL-C the “Bad Cholesterol” through the class of drugs known as statin’s along with the new PCSK9-inhibitor drugs. (5)These drug treatments also include lifestyle management such as advice regarding diet, exercise, weight control, blood pressure control, diabetes control, and smoking cessation. This includes special instructions to children of families identified with Familial Hypercholesterolemia to never start smoking given the enormous risk for cardiovascular disease. For further information on Familial Hypercholesterolemia check out the references, the registry at www.fhcanada.ca or join the FH Canada Patient Network and sign up for their e-newsletter. Our next article will expand on the treatment options including the new class of drugs available and their clinical trial results.


References:

  1. Clinicaltrials.gov A service of the U.S. National Institutes of Health; Familial Hypercholesterolemia Canada https://clinicaltrials.gov/ct2/show/NCT002009345
  2. Canadian Cardiovascular Society Position Statement on Familial Hypercholesterolemia, Canadian Journal of Cardiology 30 (2014) 1471-1481, http://dx.doi.org/10.1016/j.cjca.2014.09.028
  3. FHCanada http://www.fhcanada.net/.
  4. FH Foundation Familial Hypercholesterolemia About FH https://thefhfoundation.org/about-fh-/what-is-fh/
  5. Treating Dyslipidemia: Change is Coming; Guidelines deal with new drugs, testing and treatment strategies by Pippa Wysong Toronto; The Medical Post/News Edition 16, November 24, 2015

The articles, on the Cardiac Health Foundation of Canada website, are presented with the understanding that the Foundation is providing information only and not rendering medical advice. Please check with your family physician, specialist or health care professional before implementing any of the ideas expressed in these articles.