Prevalence and clinical characteristics of probable familial chylomicronaemia syndrome at a tertiary care center in Pakistan: Insights from a hospital-based screening study

BACKGROUND: Familial chylomicronaemia syndrome (FCS) is a rare monogenic disorder characterized by severe hypertriglyceridemia (HTG) and recurrent acute pancreatitis. Despite its significant morbidity, data from South Asian populations remain scarce. This study estimated the prevalence of probable FCS and described its clinical characteristics among individuals undergoing lipid testing at a tertiary care hospital in Pakistan. METHODS: In this retrospective, hospital-based pilot study, electronic health records of individuals undergoing lipid testing were reviewed. Severe HTG was defined as triglycerides >885 mg/dL. The FCS Clinical Score was applied to classify patients as probable FCS, unlikely FCS, and very unlikely FCS (defined as multifactorial chylomicronemia syndrome [MCS]). RESULTS: Among 95,667 individuals, 290 (0.30%) had severe HTG. Of these, 13 (4.5%) were classified as probable FCS, corresponding to a prevalence of 0.014% (14 per 100,000). Compared with MCS, FCS patients were younger (32.0 vs 43.0 years, P < .001), had lower BMI (19.2 vs 25.6 kg/m², P < .001), earlier symptom onset (15.5 vs 40.0 years, P < .001), and more frequent acute pancreatitis (30.8% vs 2.6%, P < .001). As genetic testing was not performed, these differences should be interpreted as classification-driven rather than independent findings; nonetheless, they are broadly consistent with reports from genetically confirmed FCS cohorts. CONCLUSION: This study provides the first clinical-score-based estimate of probable FCS in Pakistan. A subgroup of patients with severe HTG exhibited features suggestive of monogenic chylomicronaemia, highlighting the importance of clinical screening in resource-limited settings where genetic testing is unavailable.