Impact of Genes on Cholesterol Levels

What impact genes, what impact environment?

Ruby asked:

I often hear it said that genetics has a lot to do with a person's cholesterol levels.

1. Is that true?
   
2. If so, I wonder how many people chalk their high cholesterol up to genetics, when really they could make some changes to their diet to bring it down naturally?

While some high cholesterol is governed primarily by genes and is resistant to dietary and lifestyle changes, many other types, genetically rooted or not, respond well to these changes.

I know of at least one type of genetically transferred high cholesterol: familial hypercholesterolemia (FH). It results from a defect in a gene on chromosome 19 (shown). It's resistant to dietary and lifestyle therapies. High dose statins are usually given.

I looked up the prevalence of FH in the US. It looks to be about 1 in 500 or 0.20%.² So, if you had a group of 10,000 people, only 20 might have FH. It's considered rare.

How Many People In This Country Have High Cholesterol?

The age-adjusted prevalence for cholesterol levels over 200 mg/dl among white men age 20 and older is 47.9%, among white women is 49.7%.³ The prevalence is higher in older age groups. So, if you had a group of 10,000 adults, about half of them, or 5000, might have cholesterol over 200.

Clearly, many more people have high cholesterol than can be accounted for by an inherited disorder such as FH - a disorder not amenable to dietary and lifestyle changes.

Ruby makes a good point in the second part of her comment.
________¹ With any condition, there's no negating the effect of genes. We're alive because of genes. However, in my mind, conditions lie along a nature-nurture continuum. I've always liked this phrase: "Genetics loads the gun; environment pulls the trigger."
² CDC: Genetic Causes of Monogenic Heterozygous Familial Hypercholesterolemia: A HuGE Prevalence Review
³ American Heart Association: Cholesterol Statistics