X-Linked Lymphoproliferative Syndrome and Common Variable Immunodeficiency May Not Be Differentiated by SH2D1A and XIAP/BIRC4 Genes Sequence Analysis

Whole exome sequencing identifies compound heterozygous variants of CR2 gene in monozygotic twin patients with common variable immunodeficiency

Objectives:

A pair of female Malay monozygotic twins who presented with recurrent upper respiratory tract infections, hepatosplenomegaly, bronchiectasis and bicytopenia were recruited in this study. Both patients were suspected with primary immunodeficiency diseases. However, the definite diagnosis was not clear due to complex disease phenotypes. The objective of this study was to identify the causative gene mutation in these patients.

Methods:

Lymphocyte subset enumeration test and whole exome sequencing were performed.

Results:

We identified a compound heterozygous CR2 mutation (c.1916G>A and c.2012G>A) in both patients. These variants were then confirmed using Sanger sequencing.

Conclusion:

Whole exome sequencing analysis of the monozygotic twins revealed compound heterozygous missense mutations in CR2.

Eosinophilic colitis in a boy with a novel XIAP mutation: a case report

Background

X-linked inhibitor of apoptosis (XIAP) deficiency is a rare primary immunodeficiency disease characterized by haemophagocytic lymphohistiocytosis, recurrent splenomegaly and inflammatory bowel disease (IBD). The only curative treatment is haematopoietic stem cell transplant (HSCT).

Case presentation

Here, we report the case of a 22-month-old male with a long history of abdominal distension and anaemia. Clinical and laboratory findings were consistent with eosinophilic colitis. To identify the underlying disease, we performed exome sequencing, which showed an unreported frameshift mutation in the XIAP gene.

Conclusion

We present eosinophilic colitis as the initial manifestation of XIAP deficiency for the first time in this article, which expands the mutation spectrum and phenotype of this disease.