ESPE Abstracts

Introduction: Sitosterolaemia, is a rare autosomal recessively inherited condition. The incidence in the literature varies hugely between 1/200,000 and 1 in one million. Its incidence is likely underestimated as it is commonly misdiagnosed as familial hypercholesterolaemia. Sitosterolaemia tends to present earlier, with xanthomas, joint pains and very high total cholesterol and LDL. Routine lipid testing does not include specific testing for plant sterols. Once diagnosed sitosterolaemia can be managed effectively with dietary modifications and medications to reduce small intestinal absorption of plant sterols. If untreated there is increased risk of severe coronary artery disease and myocardial infarction early in life, highlighting the importance of timely diagnosis.

Case Description: We present the case of a previously well seven year old girl with lipid keratopathy of her left cornea present from three years of age requiring surgical intervention. On examination, she also had multiple xanthomas on her knuckles, knees and one lesion on her buttock had been surgically resected a few years previously. Initial cholesterol was 11.9mmol/L [3.0-5.0mmol/L normal range] with LDL cholesterol 10.2mmol/L [0.0-3.0mmol/L]. Initial impression was familial hypercholesterolaemia therefore genetic testing was sent and Atorvastatin 10 mg initiated. She responded to this with repeat cholesterol after 3 months 6.2mmol/L and LDL 4.37mmol/L. Genetic screen for familial hypercholesterolaemia was negative for variants in LDLR, APOB and PCSK9 genes. Further investigation revealed extremely high plant sterols. Targeted genetic analysis revealed compound heterozygous mutations in the ABCG5 gene. Dietary modification and Ezetimibe 10 mg daily has now been initiated.

Discussion: Children with sitosterolaemia may present to multiple specialities and early recognition is vital. Our patient had lipid deposits previously treated by general surgeons and had corneal deposits from age three. Definite diagnosis was not until eight years of age when corneal complications necessitated surgery. We wish to highlight the importance of awareness of lipid disorders in childhood across specialities. First line treatment for familial hypercholesterolaemia, statins, can lead to partial reduction in total cholesterol and low-density lipoprotein. This may falsely reassure physicians that the condition is the commonly encountered familial hypercholesterolaemia. Adding ezetimibe as a second line agent prior to testing serum plant sterol levels may result in false-negatives.

Conclusion: Sitosterolaemia is an important diagnosis to consider when encountering a paediatric patient with hypercholesterolaemia, particularly if clinical signs present at a young age. Genetic confirmation can aid with early identification in siblings, to prevent clinical symptoms and devastating cardiovascular complications.