Targeted NGS Revealed Pathogenic Mutation in a 13-Year-Old Patient with Homozygous Familial Hypercholesterolemia: A Case Report

Abstract

Familial hypercholesterolemia is an autosomal hereditary disease defined by an increased level of low-density lipoprotein cholesterol (LDL-C), which predisposes significant risks for premature cardiovascular disorders. We present a family trio study: proband, a 13-year-old Kazakh girl with homozygous familial hypercholesterolemia (HoFH) and her parents. HoFH is much more rare and severe than a heterozygous form of the disorder. HoFH patients generally present with LDL-C levels exceeding 13 mmol/L, resulting in early and life-threatening cardiovascular events within the first decades of life. In cases of neglected treatment, young patients have a risk of death from coronary diseases before the age of 30. The aim of this research was to identify genetic mutations in the affected patient and her parents. Genetic testing was necessary due to highly elevated LDL-C levels and the presence of multiple xanthomas. Targeted next-generation sequencing (NGS) was performed in this study using the Illumina TruSight cardio panel, which targets 174 genes related to cardiac disorders. The girl was diagnosed with HoFH based on the results of genetic testing. A biallelic mutation was observed in exon 3 of the low-density lipoprotein receptor (LDLR): c. 295 G>A (p.Glu99Lys). Sanger sequencing confirmed that the mutant gene was inherited from both parents. After confirming the genetic diagnosis of HoFH, the patient was treated with LDL apheresis and statins. This case report is the first study of HoFH in a pediatric patient from the Central Asian region. Globally, it emphasizes the need for increased clinical awareness among healthcare providers, as early detection and intervention are important for improving outcomes, particularly in pediatric patients with this rare genetic disorder.

Keywords: familial hypercholesterolemia; homozygous familial hypercholesterolemia; low-density lipoprotein receptor; mutation.

Figure 1

Xanthomas in a 13-year-old girl: (A) finger xanthomas, (B) Achilles tendon xanthomas.

Figure 2

Sanger sequencing and co-segregation analysis in the family trio. The results of c.295 G>A (p.Glu99Lys) mutation in LDLR: (A) 13-year-old girl (proband), (B) father, (C) mother. The arrows indicate peaks corresponding to a specific nucleotide (A, T, C, or G) change. Y–nucleotide code, indicating the presence of either C or T.

Figure 3

The pedigree of the family (a): III 2—proband, homozygous carrier of c. 295 G>A (p.Glu99Lys); II 1—father, heterozygous carrier of c. 295 G>A (p.Glu99Lys); II 2—mother, heterozygous carrier of c. 295 G>A (p.Glu99Lys); and the family members’ phenotypes (b).