# Clinical features and genetic analysis of a Brazilian patient with sitosterolemia: a case report

## TL;DR

A Brazilian patient with a rare genetic lipid disorder was diagnosed with sitosterolemia through genetic analysis and successfully treated with dietary changes and medication.

## Contribution

This case report highlights the importance of molecular diagnosis in managing sitosterolemia with heterogeneous clinical presentations.

## Key findings

- The patient had a homozygous p.Trp361* mutation in the ABCG8 gene.
- Treatment with ezetimibe and a restricted vegetable fat diet improved the patient's condition.
- The case emphasizes the need for genetic testing to differentiate sitosterolemia from other dyslipidemias.

## Abstract

Sitosterolemia is a rare genetic lipid disorder caused by mutations in the
ABCG5/ABCG8, genes. It is characterized by plasmatic plant
sterols accumulation, formation of tendon and tuberous xanthomas and early onset
coronary artery disease. The differential diagnosis with other congenital
dyslipidemias presents significant challenges. We describe a case of a male
patient who presented with hypercholesterolemia and tendinous xantomas from the
age of 5. The patient was born to consanguineous parents, with no family history
of hypercholesterolemia. With the initial hypothesis of cerebrotendinous
xanthomatosis, he was treated with chenodeoxycholic acid, which yielded no
improvement. Over time, he developed persistent thrombocytopenia and arthralgia,
and experienced an acute myocardial infarction at the age of 27. Genetic
analysis revealed the previously known p.Trp361*mutation in homozygosity in the
ABCG8 gene and was negative for CYP27A1
variants, associated with cerebrotendinous xanthomatosis. The subsequent
introduction of a diet with vegetable fats restriction and administration of
ezetimibe resulted in an excellent response. The diagnosis of congenital
hypercholesterolemia is challenging due to the low prevalence and heterogenous
presentation of the condition. This case underscores the importance of clinical
suspicion and the confirmation of the molecular diagnosis for a precise
therapeutic management.