Two siblings with Lisinuric Protein Intolerance (LPI) misdiagnosed as Glycogen Storage Disease type 1 (GSD 1) in resource-limited settings; a case report from Sri Lanka.

Background

LPI is a rare autosomal recessive disorder caused by defects at the anti-luminal dibasic amino acid transporter, with the highest incidence in Finland. Here we report two siblings with LPI misdiagnosed as GSD.

Case study

A 5-year-old girl presents with a fever and a seizure. On arrival, she was encephalopathic, and her GCS was 8/15. She has a round face, thin extremities and moderate hepatomegaly without splenomegaly. She had had failure to thrive.

Her 11-year-old elder sister was investigated for short stature, hepatomegaly and hyperlipidemia. She had no history of hypoglycaemia. Her basic metabolic investigations were normal. Based on the liver biopsy findings and biochemical features, she was diagnosed with GSD-1.

Due to the family history of possible GSD-1, the younger child was initially managed as an encephalitis illness on top of the underlying metabolic disorder. Her basic haematology, biochemistry, blood glucose and inflammatory parameters were normal. She had elevated ammonia glutamine and towards low normal Arginine, Ornithine and Lysine. Her urine Orotic acids were elevated, and she had normal carnitine. Her genetic studies revealed a homozygous mutation at the SLC7A7 gene (variant c.167_168del p.) suggestive of LPI. The elder sister`s genetic studies were not yet done due to financial constraints. Urine amino acids were not carried out in both patients. Both children were started on sodium Benzoate and a protein-restricted diet. L-Citrullin was not started due to unavailability.

Conclusion

Diagnosis of LPI can be challenging in a resource-limited set-up, and it is possible to be misdiagnosed as GSD-1 due to short stature, round face, hepatomegaly and hyperlipidaemia.