[Clinical features of familial hypercholesterolemia in children]

Objective: To analyze the clinical characteristics of familial hypercholesterolemia (FH) in children and provide a basis for clinical diagnosis and individualized treatment. Methods: Case series study. Clinical data of 24 children with FH, who were admitted to the Department of Endocrinology in Capital Center for Children's Health, Capital Medical University, from January 2018 to January 2025, were analyzed. Follow-ups were performed every 3-6 months and ended in January 2025. According to the results of genetic testing, the children were divided into homozygous familial hypercholesterolemia (HoFH) group and heterozygous familial hypercholesterolemia (HeFH) group. The blood lipid levels of different subtypes, the efficacy of different treatments, and clinical outcomes were compared by Mann-Whitney U test. Results: The 24 children were from 17 families, including 14 males and 10 females, with a diagnostic age of 5.0 (3.0, 9.5) years. Genetic testing results showed that 22 cases (92%) had LDLR gene variants and 2 cases (8%) had APOB gene variants, all of which were inherited from parents. There were 5 cases (21%) of HoFH and 19 cases (79%) of HeFH, and 4 previously unreported new loci were identified. There were 6 children (25%) presented with xanthomas, including 5 cases of HoFH and 1 case of HeFH. The level of low-density lipoprotein cholesterol (LDL-C) in the HoFH group was significantly higher than that in the HeFH group (P<0.05). Regarding treatment, 11 children received dietary control without taking medicine, 6 were treated with statins, 3 with ezetimibe, and 3 with statins combined with ezetimibe, and 1 underwent liver transplantation. None of the children receiving only dietary control achieved the target LDL-C level (<3.49 mmol/L or a reduction of >50%), and there was no statistically significant difference in LDL-C before and after dietary control (P=0.158). After treatment with statins and (or) ezetimibe, LDL-C decreased in 12 children (P<0.05); among them, 6 cases (all HeFH) reached the target LDL-C level. There was no statistically difference in LDL-C levels before and after treatment with atorvastatin and ezetimibe in 5 HoFH children(P>0.05). One HoFH child had LDL-C reduced to the normal range after liver transplantation. No serious adverse reactions were observed in all children during drug treatment. In the detection of vascular-related complications among 12 HeFH children, only 1 child had a slight thickening of the bilateral carotid intima-media, while no abnormalities were found in the others. Conclusions: Xanthoma is a characteristic manifestation of FH, but its incidence is relatively low in HeFH children. Family history and genetic testing are key evidences for the diagnosis of FH. Dietary control has limited efficacy in children with FH, and drug treatment should be initiated as early as possible. LDL-C levels in HoFH children are more difficult to control, if drug treatment shows poor efficacy, liver transplantation may be a better option.