Comparison of Patients With Familial Chylomicronemia Syndrome and Multifactorial Chylomicronemia Syndrome
Catherine M. Spagnuolo, Jian Wang, Adam D. McIntyre, Brooke A. Kennedy, Robert A. Hegele
Abstract
CONTEXT: Patients with rare familial chylomicronemia syndrome (FCS) and relatively common multifactorial chylomicronemia syndrome (MCS) both express severe hypertriglyceridemia, defined as plasma triglyceride concentration ≥10 mmol/L (≥885 mg/dL). Clinically there can be confusion between the 2 conditions. OBJECTIVE: To compare clinical and biochemical phenotypes in patients with genotypically characterized FCS and MCS. METHODS: We performed targeted sequencing of DNA from 193 patients with severe hypertriglyceridemia, classified them as having either FCS or MCS, and compared clinical and biochemical characteristics. RESULTS: Patients with FCS were significantly younger than patients with MCS (31.4 ± 16.7 vs 51.0 ± 11.3 years; P = .003), with earlier age at symptom onset (15.0 ± 15.8 vs 37.8 ± 8.8 years; P = .00066), lower body mass index (23.3 ± 3.1 vs 30.7 ± 5.0 kg/m2; P = .000016), and higher prevalence of pancreatitis events (81.8% vs 35.2%; P = .003). Furthermore, patients with FCS had a higher ratio of triglyceride to total cholesterol (ie, 4.18 ± 0.92 vs 1.08 ± 0.51; P < .0001) and lower plasma apolipoprotein B (ie, 0.56 ± 0.15 vs 1.02 ± 0.43 g/L; P < .0001) than patients with MCS. Patients with MCS with heterozygous pathogenic variants had a relatively more severe clinical presentation than other MCS genetic subgroups. CONCLUSION: Patients with FCS have notable phenotypic differences from patients with MCS, although there is overlap. While genetic analysis of patients with persistent severe hypertriglyceridemia can definitively diagnose FCS, 8.8% of patients with MCS with sustained refractory hypertriglyceridemia behave functionally as if they have FCS, which should influence their eligibility for novel therapies for severe hypertriglyceridemia.