Genotype and phenotype of familial hypercholesterolemia in Egyptian children: a single-center study

BACKGROUND: Familial hypercholesterolemia (FH), which is traditionally viewed as a monogenic disorder, has significant variability in its phenotypic expression, particularly its physical characteristics. Understanding the relationship between genotype and phenotype is essential for the effective diagnosis and management of this condition, especially in pediatric populations. This study aimed to investigate the correlation between genotype and phenotype in Egyptian children diagnosed with FH. METHODS: A consecutive sample of 35 Egyptian children diagnosed with FH was recruited for the study. Phenotypic characteristics were comprehensively analyzed and correlated with genetic variants. Next-generation sequencing was employed to identify pathogenic variants in genes associated with FH. RESULTS: Among the 35 cases analyzed, 33 (94.3%) were found to have pathogenic variants in the low-density lipoprotein receptor (LDLR), apolipoprotein B (APOB), or PCSK9 genes, with variants in LDLR accounting for approximately 90% of these cases. Zygosity analysis indicated that 63.6% of the children had biallelic pathogenic variants, with 42.4% being homozygous and 21.2% compound heterozygous, whereas the remaining 36.4% were heterozygous. The occurrence of xanthomas, early markers of atherosclerosis, abnormal echocardiographic findings, and elevated levels of total cholesterol and low-density lipoprotein cholesterol were significantly more common in children with homozygous FH. CONCLUSION: This study revealed a significant correlation between genotype and phenotype in Egyptian children with FH, with homozygous individuals experiencing more severe clinical symptoms. These findings underscore the importance of genetic screening in assessing disease severity and tailoring treatment strategies.