Search

Background Evidence suggests that LPA risk genotypes are a possible contributor to the clinical diagnosis of familial hypercholesterolemia (FH). This study aimed at determining the prevalence of LPA risk variants in adult individuals with FH enrolled in the Italian LIPIGEN (Lipid Transport Disorders Italian Genetic Network) study, with (FH/M+) or without (FH/M−) a causative genetic variant. Methods and Results An lp(a) [lipoprotein(a)] genetic score was calculated by summing the number risk‐increasing alleles inherited at rs3798220 and rs10455872 variants. Overall, in the 4.6% of 1695 patients with clinically diagnosed FH, the phenotype was not explained by a monogenic or polygenic cause but by genotype associated with high lp(a) levels. Among 765 subjects with FH/M− and 930 subjects with FH/M+, 133 (17.4%) and 95 (10.2%) were characterized by 1 copy of either rs10455872 or rs3798220 or 2 copies of either rs10455872 or rs3798220 (lp(a) score ≥1). Subjects with FH/M− also had lower mean levels of pretreatment low‐density lipoprotein cholesterol than individuals with FH/M+ (t test for difference in means between FH/M− and FH/M+ groups

Familial Hypercholesterolemia (FH) is a genetic disorder of lipoprotein metabolism that causes an increased risk of premature atherosclerotic cardiovascular disease (ASCVD). Although early diagnosis and treatment of FH can significantly improve the cardiovascular prognosis, this disorder is underdiagnosed and undertreated. For these reasons the Italian Society for the Study of Atherosclerosis (SISA) assembled a Consensus Panel with the task to provide guidelines for FH diagnosis and treatment. Our guidelines include: i) an overview of the genetic complexity of FH and the role of candidate genes involved in LDL metabolism; ii) the prevalence of FH in the population; iii) the clinical criteria adopted for the diagnosis of FH; iv) the screening for ASCVD and the role of cardiovascular imaging techniques; v) the role of molecular diagnosis in establishing the genetic bases of the disorder; vi) the current therapeutic options in both heterozygous and homozygous FH. Treatment strategies and targets are currently based on low-density lipoprotein cholesterol (LDL-C) levels, as the prognosis of FH largely depends on the magnitude of LDL-C reduction achieved by lipid-lowering therapies. Statins with or without ezetimibe are the mainstay of treatment. Addition of novel medications like PCSK9 inhibitors, ANGPTL3 inhibitors or lomitapide in homozygous FH results in a further reduction of LDL-C levels. LDL apheresis is indicated in FH patients with inadequate response to cholesterol-lowering therapies. FH is a common, treatable genetic disorder and, although our understanding of this disease has improved, many challenges still remain with regard to its identification and management. [ABSTRACT FROM AUTHOR]

Detection and treatment of patients with familial hypercholesterolemia (FH) starting from childhood is fundamental to reduce morbidity and mortality. The activity of National realities such as the LIPIGEN (LIpid transPort disorders Italian GEnetic Network) Paediatric Group, founded in 2018, is a milestone in this context. The aim of this exploratory survey, conducted in October 2021 among Italian lipid clinics included in the LIPIGEN Paediatric Group, was to investigate the current clinical approach in the management and treatment of paediatric patients with suspected FH. A digital questionnaire composed of 20 questions investigating nutritional treatment and nutraceutical and pharmacological therapy for children and adolescents with FH was proposed to the principal investigators of 30 LIPIGEN centres. Twenty-four centres responded to the section referring to children aged < 10 years and 30 to that referring to adolescents. Overall, 66.7% of children and 73.3% of adolescents were given lipid-lowering nutritional treatment as the first intervention level for at least 3–4 months (29.2% and 23.3%) or 6–12 months (58.3% and 53.3%). Nutraceuticals were considered in 41.7% (regarding children) and 50.0% (regarding adolescents) of the centres as a supplementary approach to diet. Lipid-lowering drug therapy initiation was mainly recommended (91.7% and 80.0%). In 83.3% of children and 96.7% of adolescents, statins were the most frequently prescribed drug. We highlighted several differences in the treatment of paediatric patients with suspected FH among Italian centres; however, the overall approach is in line with the European Atherosclerosis Society (EAS) recommendations for FH children and adolescents. We consider this survey as a starting point to reinforce collaboration between LIPIGEN centres and to elaborate in the near future a consensus document on the management of paediatric patients with suspected FH so as to improve and uniform detection, management, and treatment of these patients in our country.

Pathology registers can be a useful tool to overcome obstacles in the identification and management of familial hypercholesterolemia since childhood. In 2018, the LIPIGEN pediatric group was constituted within the Italian LIPIGEN study to focus on FH subjects under 18 years. This work aimed at discussing its recent progress and early outcomes. Demographic, biochemical, and genetic baseline characteristics were collected, with an in-depth analysis of the genetic defects. The analysis was carried out on 1,602 children and adolescents (mean age at baseline 9.9 ± 4.0 years), and almost the whole cohort underwent the genetic test (93.3%). Overall, the untreated mean value of LDL-C was 220.0 ± 97.2 mg/dl, with an increasing gradient from subjects with a negative (N = 317; mean untreated LDL-C = 159.9 ± 47.7 mg/dl), inconclusive (N = 125; mean untreated LDL-C = 166.4 ± 56.5 mg/dl), or positive (N = 1,053; mean untreated LDL-C = 246.5 ± 102.1 mg/dl) genetic diagnosis of FH. In the latter group, the LDL-C values presented a great variability based on the number and the biological impact of involved causative variants. The LIPIGEN pediatric group represents one of the largest cohorts of children with FH, allowing the deepening of the characterization of their baseline and genetic features, providing the basis for further longitudinal investigations for complete details.

Lorenzo de’ Medici, uomo di profonda fede, data la mirabile educazione ricevuta in famiglia, accettò il governo della città dopo la morte del padre, Piero il Gottoso, come dovere, sentendone il peso, data la sua giovane età di 21 anni, secondo quanto lui stesso dice “mal volentieri accettai”. In tutta la sua vita, non molto lunga, privilegiò come fine il conseguimento del bene comune e non il proprio interesse. Attento anche alle situazioni dei meno fortunati, come il popolo fiorentino e i contadini del Mugello, si rivelò un abile politico che riuscì ad equilibrare la politica dei vari staterelli italiani, ma non dimenticò mai quale fosse il traguardo vero della vita dell’uomo e cioè guardare verso Dio staccandosi dalle ambizioni della vita terrena. Soprattutto raccomandò ai figli di saper governare diventando esempio “perché il signore deve essere servo de’ suoi servi” come scrive nella Sacra rappresentazione di Giovanni e Paolo messa in scena il 17 febbraio 1491 nella Compagnia del Vangelista.

BackgroundExome sequencing is a promising tool for gene mapping in Mendelian disorders. We used this technique in an attempt to identify novel genes underlying monogenic dyslipidemias.Methods and resultsWe performed exome sequencing on 213 selected family members from 41 kindreds with suspected Mendelian inheritance of extreme levels of low-density lipoprotein cholesterol (after candidate gene sequencing excluded known genetic causes for high low-density lipoprotein cholesterol families) or high-density lipoprotein cholesterol. We used standard analytic approaches to identify candidate variants and also assigned a polygenic score to each individual to account for their burden of common genetic variants known to influence lipid levels. In 9 families, we identified likely pathogenic variants in known lipid genes (ABCA1, APOB, APOE, LDLR, LIPA, and PCSK9); however, we were unable to identify obvious genetic etiologies in the remaining 32 families, despite follow-up analyses. We identified 3 factors that limited novel gene discovery: (1) imperfect sequencing coverage across the exome hid potentially causal variants; (2) large numbers of shared rare alleles within families obfuscated causal variant identification; and (3) individuals from 15% of families carried a significant burden of common lipid-related alleles, suggesting complex inheritance can masquerade as monogenic disease.ConclusionsWe identified the genetic basis of disease in 9 of 41 families; however, none of these represented novel gene discoveries. Our results highlight the promise and limitations of exome sequencing as a discovery technique in suspected monogenic dyslipidemias. Considering the confounders identified may inform the design of future exome sequencing studies.

• Four subjects with familial chylomicronemia syndrome were identified. • Sixty-year clinical/biochemical follow-up was performed in 2 affected patients. • Genetic analysis disclosed a single LPL gene defect (c.984 G>T) in homozygosity. • Cardiovascular disease/pancreatitis prevalence and long-term survival are discussed. Familial chylomicronemia syndrome (FCS) is a rare and severe genetic disorder, characterized by marked elevation of plasma triglycerides, often diagnosed in infancy. We describe the long-term follow-up (almost 60 years), the diagnostic assessment and the management of two siblings with severe hypertriglyceridemia and a history of pancreatitis who also developed cardiovascular complications later in life. We recently disclosed that the surviving index case was homozygous for a pathogenic LPL gene variant (c.984 G>T, p.M328I). The same variant was also found in two apparently unrelated siblings with FCS living in the same geographical area as the index case. [Display omitted] [ABSTRACT FROM AUTHOR]

• Primary hypobetalipoproteinemia (HBL) can be either monogenic or polygenic. • We compared two polygenic risk scores (PRS1-PRS2) in primary HBL. • Among 170 subjects with primary HBL, 37% had a polygenic origin. • Prevalence of liver steatosis did not differ in monogenic and polygenic HBL. • Only PRS1 is effective in detecting polygenic HBL. Primary Hypobetalipoproteinemias (HBL) are a group of dominant and recessive monogenic genetic disorders caused by mutations in APOB, PCSK9, ANGPTL3, MTTP, Sar1b genes and characterized by plasma levels of total cholesterol (TC), low density lipoprotein-cholesterol (LDL-C) and apolipoprotein B (apoB) below the 5th percentile of the distribution in a given population. Mutations in the candidate genes account only for a small proportion of subjects with HBL suggesting a role for a polygenic contribution to the low cholesterol phenotype. To explore the complex genetic architecture of HBL we compared two polygenic risk scores in order to assess the role of the polygenic burden and the differences in the clinical phenotype between monogenic and polygenic HBL; we studied a cohort of 170 subjects with primary HBL referred over a 25-year period to 2 Italian reference centers have been studied. The genetic analyses have been based on: Sanger sequencing, in-house NGS customized panel and two scores, PRS1 and PRS2 for the polygenic burden. Sixty 60 (35%) and 63 (37%) subjects had a monogenic and polygenic HBL respectively. LDL-C plasma levels were significantly lower in monogenic HBL (30.87 ± 3.12 mg/dl) compared with the non-monogenic HBL (42.80 ± 2.18 mg/dl) (p<0.002) with no differences in the percentage of fatty liver. Only PRS1 is effective in detecting polygenic HBL while PRS2 does not improve the polygenic diagnosis. [ABSTRACT FROM AUTHOR]

Familial hypobetalipoproteinemia type 1 (FHBL-1) is a codominant disorder characterized by greatly reduced plasma levels of total cholesterol, low-density lipoprotein cholesterol, and apolipoprotein B. Rare exonic pathogenic variants of APOB gene (nonsense variants, minute deletions/insertions and nonsynonymous variants) have been frequently reported in subjects with FHBL-1. Also, rare intronic variants of APOB located at intron/exon junctions and assumed to affect splicing have been reported. However, the pathogenicity of most of these intronic variants remains to be established. The objective of this study was the in vitro functional characterization of six splicing variants of APOB gene identified in seven putative FHBL-1 heterozygotes. ApoB minigenes harboring each variant were expressed in COS-1 cells and their transcripts were sequenced. Four novel variants (c.237+1G>A, c.818+5G>A, c.3000-1G>T, and c.3842+1G>A), predicted in silico to obliterate splice site activity, were found to generate abnormal transcripts. The abnormal transcripts were generated by the activation of cryptic splice sites or exon skipping. All these transcripts harbored a premature termination codon and were predicted to encode truncated apoBs devoid of function. The predicted translation products were: i) p.(Lys41Serfs*2) and p.(Val80Ilefs*10) for c.237+1G>A; ii) p.(Asn274*) for c.818+5G>A; iii) p.(Leu1001Alafs*10) for c.3000-1G>T, and iv) p.(Ser1281Argfs*2) for c.3842+1G>A. Two previously annotated rare variants (c.905-15C>G and c.1618-4G>A) with uncertain effect in silico were found to generate only wild-type transcripts. These in vitro minigene expression studies support the assignment of pathogenicity to four novel splice site variants of APOB gene found in FHBL-1. • APOB gene variants may be the cause of familial hypobetalipoproteinemia (FHBL-1). • Six rare APOB intronic variants involving splice sites were found in FHBL-1 subjects. • The functional impact of each variant was assessed in vitro using minigene strategy. • Four variants were found to generate abnormal transcripts encoding truncated apoBs. [ABSTRACT FROM AUTHOR]

Intestinal lipid malabsorption, resulting from an impaired formation or secretion of chylomicrons and associated with severe hypobetalipoproteinemia (HBL), may be due to biallelic mutations in APOB (homozygous FHBL type-1), MTTP (abetalipoproteinemia), or SAR1B (chylomicron retention disease). We investigated four children, each born from consanguineous parents, presenting with steatorrhea, malnutrition, accumulation of lipids in enterocytes, and severe hypocholesterolemia with an apparent recessive transmission. We sequenced a panel of genes whose variants may be associated with HBL. Case 1, a 9-month-old male, was found to be homozygous for a SAR1B variant (c.49 C>T), predicted to encode a truncated Sar1b protein devoid of function (p.Gln17*). Case 2, a 4-year-old male, was found to be homozygous for a SAR1B missense variant [c.409 G>C, p.(Asp137His)], which affects a highly conserved residue close to the Sar1b guanosine recognition site. Case 3, a 6-year-old male, was found to be homozygous for an ∼6 kb deletion of the SAR1B gene, which eliminates exon 2; this deletion causes the loss of the ATG translation initiation codon in the SAR1B mRNA. The same homozygous mutation was found in an 11-month-old child (case 4) who was related to case 3. We report 4 children with intestinal lipid malabsorption were found to have chylomicron retention disease due to 3 novel variants in the SAR1B gene. • Phenotype of children with lipid malabsorption and recessive hypobetalipoproteinemia. • Analysis of MTTP and SAR1B candidate genes for recessive hypobetalipoproteinemia. • Identification of three new SAR1B gene mutations causing chylomicron retention disease. [ABSTRACT FROM AUTHOR]