# GPIHBP1 Autoantibody‐Related Hypertriglyceridemia in a 12‐Year‐Old Girl With Systemic Lupus Erythematosus

## TL;DR

A 12-year-old girl with lupus had high triglycerides caused by autoantibodies against a protein that helps break down fats, a rare condition confirmed after ruling out other causes.

## Contribution

This case highlights GPIHBP1 autoantibody-related hypertriglyceridemia as a rare but important cause in patients with autoimmune disease.

## Key findings

- The patient had elevated GPIHBP1 autoantibody titer and low LPL mass, confirming GPIHBP1 autoantibody syndrome.
- Triglyceride levels and autoantibody levels normalized after 2 years of treatment with immunosuppressants.
- Autoimmune hypertriglyceridemia should be considered after excluding genetic and common secondary causes.

## Abstract

Glycosylphosphatidylinositol‐anchored high‐density lipoprotein‐binding protein 1 (GPIHBP1) is critical for transporting lipoprotein lipase (LPL) to the capillary lumen, where LPL breaks down triglycerides in triglyceride‐rich lipoproteins. We herein report a 12‐year‐old Chinese girl who presented with severe hypertriglyceridemia and a recent diagnosis of systemic lupus erythematosus (SLE). She was first noted to have severe hypertriglyceridemia at 8.5 years old, complicated by three episodes of acute pancreatitis within 2 years. Between these episodes, her plasma triglycerides remained elevated, but at lower levels. Next‐generation sequencing for primary hypertriglyceridemia yielded no significant findings. Investigations for secondary causes, to include fasting glucose, HbA1c, and thyroid function testing, were unrevealing. Given the fluctuating triglyceride levels and negative genetic testing for primary hypertriglyceridemia in the background of SLE, autoimmune hypertriglyceridemia was suspected. The diagnosis of GPIHBP1 autoantibody syndrome was confirmed by an elevated GPIHBP1 autoantibody titer and a low LPL mass in her serum. Her SLE was well controlled with immunosuppressants and belimumab. Fenofibrate and omega‐3 fatty acids, which were initially prescribed for her hypertriglyceridemia, were later discontinued. The GPIHBP1 autoantibody and LPL mass normalized 2 years after diagnosis. This case illustrates hypertriglyceridemia caused by a rare disease entity associated with autoantibodies against the GPIHBP1 protein. This entity is worth considering after excluding genetic and common secondary causes of hypertriglyceridemia, particularly in a patient with a history of autoimmune disease.