A case report of an Egyptian family with familial hypercholesterolemia and an exonic LINE-1 insertion in LDLR

Background: Familial hypercholesterolemia (MIM: PS143890) is a genetic disorder characterized by an increase in blood cholesterol. LDLR is one of the genes which their defect contributes to the disorder. Affected individuals may carry a heterozygous variant or homozygous/compound heterozygous variants and those with biallelic pathogenic variants present more severe symptoms.

Method: We report an Egyptian family with familial hypercholesterolemia. Both the proband and parents have the disorder while a sibling is unaffected. Exome sequencing was performed to identify the causal variant.

Results: LINE-1 insertion in exon 7 of LDLR was identified. Both parents have a heterozygous variant while the proband has a homozygous variant. The unaffected sibling did not carry the variant.

Discussion: This insertion may contribute to the high prevalence of hypercholesterolemia in Egypt and the finding underscores the importance of implementing mobile element insertion caller in routine bioinformatics pipeline.