👤 Cecilia Nobili

Early diagnosis of familial hypercholesterolemia (FH) is crucial to improve long-term outcomes. FH diagnosis relies on elevated low-density lipoprotein cholesterol (LDL-C) levels, familial clinical characteristics, and identification of pathogenic variants in FH-related genes. Secondary factors, such as overweight and obesity, are known to influence lipid profiles in the general population. More recently, polygenic risk scores based on single-nucleotide polymorphisms (SNPs) have been proposed as additional determinants of LDL-C levels. We enrolled 214 pediatric subjects with LDL-C levels ≥95th percentile (after 6 months of dietary intervention) and with at least one parent with LDL-C levels ≥ 95th percentile. All participants underwent biochemical and auxological assessment and genetic testing for FH. In a subgroup of 60 subjects, LDL-C polygenic scores based on 6- and 12-SNPs were calculated. Pathogenic variants confirming heterozygous FH were identified in 190 subjects (variant-positive, V+); 17 were variant-negative (V-), yielding a mutation detection rate of 91.8%. An additional seven patients carrying variants of uncertain significance were excluded from the primary analysis. LDL-C was modestly higher in V+ than V- subjects using both Friedewald (212 vs. 188 mg/dL; In children selected by LDL-C ≥ 95th percentile, together with autosomal dominant familial hypercholesterolemia, genetic confirmation of FH is achieved in the vast majority of cases. Variant type (null vs. defective), BMI, and polygenic background contribute to phenotypic heterogeneity, supporting the need to address other factors alongside genetic diagnosis. Further validation is needed before polygenic scores can be implemented in routine clinical practice. Show less

FADS1 gene encodes delta 5 desaturase, a rate-limiting enzyme in the metabolism of n-3 and n-6 polyunsaturated fatty acids (PUFAs). Minor alleles of FADS1 locus polymorphisms are associated with reduced FADS1 expression and intra-hepatic fat accumulation. However, the relationship between FADS1 expression and pediatric nonalcoholic fatty liver disease (NAFLD) risk remains to be explored. We analyzed FADS1 transcription levels and their association with intra-hepatic fat and histology in children, and we performed pathway enrichment analysis on transcriptomic profiles associated with FADS1 polymorphisms. We also evaluated the weight of FADS1 alleles on the response to combined docosahexaenoic acid, choline, and vitamin E (DHA-CHO-VE) treatment. FADS1 mRNA level was significantly and inversely associated with intra-hepatic fat (p = 0.004), degree of steatosis (p = 0.03), fibrosis (p = 0.05), and NASH (p = 0.008) among pediatric livers. Transcriptomics demonstrated a significant enrichment of a number of pathways strongly related to NAFLD (e.g., liver damage, fibrosis, and hepatic stellate cell activation). Compared to children who are common allele homozygotes, children with FADS1 minor alleles had a greater reduction in steatosis, fibrosis, and NAFLD activity score after DHA-CHO-VE. This study suggests that decreased FADS1 expression may be associated with NAFLD in children but an increased response to DHA-CHO-VE. Show less

The T-455C and C-482T APOC3 promoter region polymorphisms (SNPs) have recently been reported to predispose to dyslipidemia, insulin resistance, and nonalcoholic fatty liver disease (NAFLD) in Indian subjects, but the association with liver damage has not been evaluated so far. The aim was to assess the association between APOC3 SNPs and liver damage in Caucasian patients. We considered 437 Italian patients with histological diagnosis of NAFLD (including 137 children, 120 morbid obese) and 316 healthy controls, 71 Italian family trios, and 321 patients from the UK. APOC3 SNPs were determined by sequencing, allele-specific oligonucleotide probes and PCR-restriction fragment length polymorphism analysis, hepatic APOC3 mRNA levels by real-time PCR. APOC3 SNPs were not associated with NAFLD in Italian subjects, although a borderline significance for the transmission of the -455T allele was observed in the family study. Homozygosity for the APOC3 wild-type genotype (APOC3 WT) was associated with a more favorable lipid profile in control subjects, and consistently with lower hepatic APOC3 mRNA levels in obese patients without diabetes. However, APOC3 SNPs, alone or in combination, were not associated with insulin resistance, altered lipid levels, liver enzymes, and with liver damage (severity of steatosis, nonalcoholic steatohepatitis, and moderate/severe fibrosis) in Italian as well as in UK patients, and in the whole cohort. Stratification for the I148M PNPLA3 mutation, associated with the susceptibility to NASH, did not alter the results. APOC3 genotype is not associated with progressive liver damage in Caucasian patients with NAFLD. Show less