Familial hypercholesterolaemia

Familial hypercholesterolaemia

What do I need to know?

FH is a lipid disorder that leads to premature cardiovascular disease (CVD). FH most often follows an autosomal dominant inheritance When a condition follows an autosomal dominant pattern of inheritance, the family tree will usually reveal multiple affected members in multiple generations on the same side of the family. Dominant conditions or traits are expressed when only a single is inherited. Wide variability in clinical expression is common in many autosomal dominant conditions, even within the same family. Early onset of conditions, such as cancer, can be indicative of autosomal dominant inheritance within a family. Not all dominant conditions show 100% penetrance (eg BRCA1 gene mutations). pattern. If FH is left untreated, males have a 50% chance of developing CVD before 50 years of age, and women have a 30% chance of developing CVD by 60 years of age. Early diagnosis and treatment of FH reduces the risk of CVD.

The risk of FH can be assessed using the Dutch Lipid Clinic Network Criteria (DLCNC).

FH assessment should be conducted when an individual presents with:

• clinical features such as tendon xanthomata
• untreated low-density lipoprotein cholesterol (LDL-C) >4.9 in adults mmol/L
• premature CVD or a family history of such (CVD aged < 60 years).

Genetic testing

While FH can be diagnosed clinically, a confirmatory DNA test allows for cascade screening Cascade screening involves testing the close biological relatives of an individual who has or is a carrier of a genetic condition in order to determine whether these relatives carry the genetic variant or chromosomal alternation (thereby increasing their chances of developing the condition or having a child with the condition). For example, cascade testing is available under the Medicare Benefits Schedule for genetic testing for familial hypercholesterolaemia. within the family of an affected patient. There is MBS funding for genetic testing for FH. MBS item 73352 can only be ordered by specialist physician to make the diagnosis; GPs can order the test for cascade screening.

When should I refer?

Refer individuals with a DLCNC score of ≥3 (ie possible-to-definite FH) to a cardiologist or lipid clinic for confirmation of diagnosis, including possible genetic testing.

Other considerations

Those diagnosed with FH should be encouraged to:

• inform family members that they may be at increased risk of FH
• direct family members to further information about FH
• advise family members to discuss their risk of FH with their GP