Successful pharmacological management of a child with compound heterozygous familial hypercholesterolemia and review of the recent literature

Abstract

Severe familial hypercholesterolemia (SFH) is characterized by markedly elevated low-density lipoprotein cholesterol (LDL-C) and severe early-onset cardiovascular disease if left untreated. We report on the decade-long therapeutic journey of a 15-year-old boy with SFH due to a severe compound heterozygous genotype. He presented at the age of 5 years with widespread xanthomas and LDL-C of 17.4 mmol/L. He was diagnosed with SFH, initially treated with colestyramine that was subsequently combined with simvastatin. At the age of 12 years, he was diagnosed to have supravalvular aortic stenosis and ezetimibe/atorvastatin was introduced in place of colestyramine/simvastatin. At the age of 14 years, he received triple therapy with evolocumab, initially at the recommended dose of 420 mg monthly and then reduced to 140 mg biweekly. Currently at the age of 15 years, he is on atorvastatin 40 mg ON, ezetimibe 10 mg OM, and evolocumab 140 mg biweekly, achieving LDL-C levels of 2.4 mmol/L. Genetic testing identified compound heterozygous mutations in the LDL receptor genes [c.(940 + 1_941-1) (1845 + 1_1846-1)dup] and exon 12, nucleotide c.1747 C > T, amino acid p.(His583Tyr). Medical management without lipoprotein apheresis can achieve target LDL-C in children with SFH. Our patient, who developed supravalvular aortic stenosis at the age of 12 years, needed early aggressive treatment when SFH guidelines and newer drugs for young children were unavailable. Our patient demonstrated that 140 mg biweekly of evolocumab has the same cholesterol-lowering effect as the recommended 420 mg monthly dose.

Keywords: Compound heterozygous familial hypercholesterolemia; Genetic testing; Homozygous familial hypercholesterolemia; Medical therapy; Severe familial hypercholesterolemia; Supravalvular aortic stenosis.