👤 M Mangas

Severe hypertriglyceridemia (fasting triglycerides >500 mg/dL) is an uncommon and heterogeneous condition in children. The aim of this work was to assess the etiology of severe hypertriglyceridemia seen in 8 pediatric patients. Eight pediatric cases with severe hypertriglyceridemia underwent clinical, biochemical, and genetic evaluations. The laboratory tests performed included lipoprotein separation by ultracentrifugation and measurement of their lipid content, measurement of apolipoproteins, analyses of post-heparin plasma lipoprotein lipase (LPL) activity and mass, detection of autoantibodies against GPIHBP1, and targeted next-generation sequencing. All children (3-16 years) had recorded fasting serum triglyceride levels >800 mg/dL (9 mmol/L) at least once. Five cases with pathogenic or likely pathogenic biallelic variants in GPIHBP1 (2 cases), APOA5 (1 case), APOC2 (1 case), and LPL (1 case) were diagnosed with familial chylomicronemia syndrome based on their clinical, biochemical, and genetic features. Additionally, 1 child had autoimmune chylomicronemia due to the presence of autoantibodies against GPIHBP1. Finally, 2 patients had severe hypertriglyceridemia due to secondary causes: 1 girl with the onset of type 1 diabetes in the context of diabetic ketoacidosis, and the other patient due to total parenteral nutrition and low-molecular-weight heparin. The etiology of severe hypertriglyceridemia in children is heterogeneous. A multidisciplinary approach helps to reach a definitive diagnosis and, therefore, to recommend specific therapy. Show less

Familial chylomicronemia syndrome (FCS) is an extremely rare lipoprotein disorder caused by mutations in at least 5 genes of the lipoprotein lipase (LPL) complex. This work shows the molecular analysis of patients diagnosed with FCS, who attended the Spanish Arteriosclerosis Society lipid units and were included in the National Dyslipidemia Registry. Among the 238 patients registered with severe hypertriglyceridemia (fasting triglycerides >1000 mg/dL), 26 were diagnosed with FCS as they had confirmed postheparin plasma LPL activity deficiency and/or homozygosity for loss-of-function mutations in LPL, GPIHBP1, APOC2, LMF1, or Apolipoprotein A5 (APOA5). Among the 26 FCS cases, 23 had mutations in the homozygous state: 19 in LPL and 4 in the GPIHBP1 gene. The molecular analysis revealed 3 novel mutations: 2 in LPL, in 2 unrelated patients (c.312delA; p.Asp105Thrfs*66 and c.629A>G; p.His210Arg), and 1 in GPHIBP1 in a third patient (c.502delC; p.Leu168Serfs*83). These 3 patients had confirmed lack of LPL activity. Three additional patients with confirmed LPL activity deficiency were heterozygous carriers of mutations in the genes analyzed. Among these, we found 2 novel mutations in APOA5 (c.50-1G>A and c.326₃₂₇insC; p.Tyr110Leufs*158). We have identified 5 novel pathogenic mutations: 2 in LPL, 1 in GPIHBP1, and 2 in the APOA5 gene. The genetic defaults accounting for the LPL activity deficiency of 23 of them have been clearly identified and 3 patients, who harbored mutations in heterozygosity, were diagnosed based on LPL activity deficiency, which raises the question of the involvement of new genes in the manifestation of FCS. Show less

The neuronal ceroid-lipofuscinoses are the most common neurodegenerative disorders in childhood characterized by progressive blindness, epilepsy, brain atrophy, and premature death. Based on the age at onset, disease progression and ultrastructural features three classical (infantile, late-infantile, and juvenile) and three variant late-infantile forms are generally distinguished (Finnish variant, Costa Rican variant, and epilepsy with progressive motor retardation). The Finnish variant late-infantile form has been associated with CLN5 gene defects, with only five mutations described to date. We report a patient with vLINCL/CLN5 who represents the first evidence of the disease in the Portuguese population. Mutational screening revealed the previously described missense mutation c.835G>A (D279N) inherited from the mother, and two novel mutations, c.565C>T (Q189X) and c.335G>C (R112P) from paternal and maternal inheritance, respectively. Based on data here reported: (i) the number of possible mutations in CLN5 gene is now 7; (ii) the CLN5 Portuguese case represents the third description of the disease outside northern Europe; (iii) the CLN5/mRNA expression level reduced to 45% supports the existence of one mRNA non-producing allele, further noticeable at the protein level; (iv) Western blotting data using a specific antibody to human CLN5p provided evidence for the presence of four integral membrane isoforms in human fibroblasts; (v) data from differential expression of CLN2, CLN3, and CLN5 suggest down-regulation of CLN3 gene expression in CLN2 and CLN5-deficient human patients and this observation strengths the hypothesis of functional redundancy of the CLN system. Show less