Analysis of a Chinese Pedigree With Familial Chylomicronemia Syndrome Reveals Two Novel LPL Mutations by Whole-Exome Sequencing

Ying Liu,Shuangchuan Zhang,Wenyong Zhang,Zhangzhang Lan,Fang Zhao

doi:10.3389/fgene.2020.00741

Abstract

Familial chylomicronemia syndrome (FCS) is a rare monogenic autosomal recessive disease caused by loss-of-function mutations in genes involved in chylomicron breakdown through hydrolysis of triglycerides into free fatty acids. Patients are often diagnosed in early childhood with extremely high triglyceride levels and symptoms including abdominal pain, eruptive cutaneous xanthomata, hepatosplenomegaly, and significant cognitive, psychological, and social impairment. The most serious medical condition suffered by FCS patients is recurrent acute pancreatitis. Lipoprotein lipase (LPL) gene mutation accounts for majority of the known pathogenic mutations. Early diagnosis and strict low-fat diet are critical for successful management of the triglyceride concentration to lower the risk of pancreatitis. The true prevalence of FCS in China is unknown and here we report a Chinese female preterm neonate presented with an extremely high triglyceride level of 22.11 mmol/L on day 13 after birth. Clinical and laboratory workup including whole-exome sequencing revealed two novel compound heterozygous LPL mutations (c.406G > C and c.829G > C) that are co-segregated with her non-consanguineous parents, consistent with autosomal recessive inheritance. A diagnosis of FCS based on clinical, biochemical, and genetic ground was made to guide her management.

Highlights

Familial chylomicronemia syndrome (FCS, OMIM 238600) is characterized by very severe hypertriglyceridemia (Berglund et al, 2012; Hegele et al, 2014)
Chylomicronemia syndrome consists of two distinctive forms: rare monogenic early onset chylomicronemia and more commonly encountered polygenic chylomicronemia of adulthood (Berglund et al, 2012; Hegele et al, 2014)
FCS patients are deficient in chylomicrons clearance, suffering from a plethora of symptoms resulting from an extremely high plasma triglyceride level

Summary

Introduction

Familial chylomicronemia syndrome (FCS, OMIM 238600) is characterized by very severe hypertriglyceridemia (Berglund et al, 2012; Hegele et al, 2014). LPL mutations account for 95% of all monogenic mutations associated with FCS (Murthy et al, 1996; Brahm and Hegele, 2015). Diagnosis of FCS is a complex process that involves clinical, biochemical, and genetic analysis (Beil et al, 1982). FCS may be underdiagnosed, and its true prevalence is underreported as specialized tests including LPL activity analysis and comprehensive genetic test may not be available when diagnosis is made (Davidson et al, 2017; Falko, 2018)

Methods

Results

Conclusion