Homozygous familial hypercholesterolemia (FH) can be diagnosed if certain findings are present.

NOTE: A person may be designated as homozygous FH and not be homozygous (if compound heterozygous, if LDL-C is sufficiently high, or if autosomal recessive).


LDL-cholesterol raising genetic defects include:

(1) mutations in LDL-receptor

(2) mutations in apolipoprotein B

(3) mutations in PCSK9


Clinical criteria for homozygous familial hypercholesterolemia - both of the following:

(1) LDL-cholesterol >= 400 mg/dL

(2):one or both parents have one of the following:

(2a) clinically diagnosed with familial hypercholesterolemia

(2b) positive for an LDL-C raising mutation

(2c) have autosomal recessive familial hypercholesterolemia


Genetic criteria - one of the following:

(1) two identical LDL-cholesterol raising genetic defects (true homozygous)

(2) two nonidentical (compound heterozygous) LDL-cholesterol raising genetic defects

(3) autosomal recessive familial hypercholesterolemia


If a patient has 1 abnormal LDL-C raising genetic defect AND a serum LDL-C > 400 mg/dL, then the patient is treated as a homozygous.


A patient may be homozygous for an LDL-cholesterol raising mutations AND have an LDL-C < 400 mg/dL.

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