Two cases of successful sirolimus treatment for patients with activated phosphoinositide 3-kinase δ syndrome 1

BACKGROUND: Activated phosphoinositide3-kinase (PI3K) δ syndrome 1 (APDS1) is a novel inborn errors of immunity (IEIs) caused by heterozygous gain of function mutations in PI3Kδ catalytic p110δ (PIK3CD).

APDS1 has a spectrum of clinical manifestations.

Recurrent respiratory infections, lymphoproliferation, hepatosplenomegaly, hyper-IgM syndrome and autoimmunity are the common symptoms of this disease.

CASE PRESENTATION: Patient 1 presented with recurrent respiratory infections, hepatosplenomegaly and hyper-IgM syndrome.

Patient 2 developed early onset systemic lupus erythematosus (SLE)-like disease with resistant thrombocytopenia.

c.3061 G > A and c.2314G > A variants in the PIK3CD gene were detected by whole exome sequencing in two patients respectively.

c.2314G > A variant in PIK3CD gene of patient 2 is a newly report.

After genetic diagnosis, two patients received sirolimus treatment and sirolimus alleviated clinical manifestations, including hepatosplenomegaly in patient 1 and thrombocytopenia in patient 2.

CONCLUSION: Genetics diagnosis should be considered in patients with complicated clinical manifestations with no or insufficient response to the conventional therapies.

If whole exome sequencing suggests a variant in PIK3CD gene, sirolimus may relieve hepatosplenomegaly and resistant thrombocytopenia.

This is the first report of c.2314G > A variant in PIK3CD gene.

SUPPLEMENTARY INFORMATION: The online version contains supplementary material available at 10.1186/s13223-023-00840-0.