Diagnosis of Hyper IgM syndrome in a Previously Healthy Adolescent Boy Presented with Cutaneous and Cerebral Cryptococcosis

A novel hemizygous CD40L mutation of X-linked hyper IgM syndromes and compound heterozygous DOCK8 mutations of hyper IgE syndromes in two Chinese families

X-linked hyper-immunoglobulin M (X-HIGM) syndrome and autosomal recessive hyper-immunoglobulin E syndrome (HIES) are rare inborn errors of immunity characterized by recurrent infections due to immune system impairment. In this study, we identified a novel hemizygous CD40 ligand (CD40L) mutation and compound heterozygous dedicator of cytokinesis-8 (DOCK8) mutations in two Han Chinese families with X-HIGM and HIES, respectively. We aimed to investigate the association between their genotypes and phenotypes. Genomic DNA was extracted from peripheral blood samples obtained from the families. Whole exome sequencing and Sanger sequencing were performed to identify and verify pathogenic variants in the two families. Clinical analyses of the probands were also performed. A novel hemizygous mutation of CD40L in exon 2 (c.257delA) was identified in the first proband, resulting in the substitution of glycine with glutamic acid at codon 86 of the protein. This leads to premature termination of translation at downstream codon 9 (p.E86Gfs*9). Sanger sequencing confirmed that the variant was inherited from the mother. The second proband carried two novel compound heterozygous mutations in DOCK8: one at exon 14 (c.1546C > G) inherited from the father, and the other at intron 41 (c.5355 + 6C > T; splicing) inherited from the mother. This study enhances our understanding of the pathogenetic mutation spectrum of CD40L and DOCK8 genes, facilitating the prenatal diagnosis of X-HIGM and HIES and enabling timely treatment of patients.

Inborn Errors of Immunity Causing Pediatric Susceptibility to Fungal Diseases

Inborn errors of immunity are a heterogeneous group of genetically determined disorders that compromise the immune system, predisposing patients to infections, autoinflammatory/autoimmunity syndromes, atopy/allergies, lymphoproliferative disorders, and/or malignancies. An emerging manifestation is susceptibility to fungal disease, caused by yeasts or moulds, in a superficial or invasive fashion. In this review, we describe recent advances in the field of inborn errors of immunity associated with increased susceptibility to fungal disease.

Exome sequencing contributes to identify comorbidities in a rare case of infant ARDS induced by the CD40LG mutation

Background

Acute respiratory distress syndrome (ARDS) causes significant mortality in young children with certain diseases. Early diagnosis and treatment can reduce infant mortality. Here, we report a rare case of exome sequencing in the early diagnosis of immunodeficiency in an infant.

Case presentation

A four-month-old full-term male infant presented with severe shortness of breath, hypoxemia, and unexplained parenchymal lung lesions. A series of examinations were performed to search for potential culprit viruses but negative results were obtained with the only exception being the rhinovirus that tested positive. The child’s family history revealed he had a brother who died of severe infection at the age of two years. We performed an exome sequencing analysis and a mutation analysis of CD40LG to obtain genetic data on the patient. Besides, we used flow cytometry to measure the CD40LG expression levels of activated T cells. A retrospective review of all the CD40LG mutant-induced X-linked hyper IgM syndromes (XHIGM) had been conducted to assess the differences between clinical and genetic molecular features. Finally, a regular intravenous immunoglobulin (IVIG) regimen led to steady breathing, the correction of hypoxemia, and a progressive improvement of lung CT scans. During follow-up, the patient received an IVIG regimen and his CT images improved. Moreover, his parents took advantage of pre-implantation genetic testing with in vitro fertilization to have a healthy twin offspring who did not carry such a mutation according to the early exome sequencing for the proband. Compared with other CD40LG mutant cases in our center, this proband displayed a normal plasma immunoglobulin level and he should be the youngest infant to have a molecular diagnosis of XHIGM.

Conclusion

Usually, XHIGM would not be suspected with a normal plasma immunoglobulin concentration. However, as we could not identify a potential comorbidity or risk factor, exome sequencing helps target this patient's real facts. Thus, this case report calls for exome sequencing to be performed in the case of unexplained infections when immunodeficiency is suspected after general immunological tests, especially for cases with a contributive family history among infants as the maternal transfused immunoglobulin might mask immune deficiency.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12920-022-01303-y.

Phenotypic heterogeneity and genotypic spectrum of inborn errors of immunity identified through whole exome sequencing in a Thai patient cohort

BACKGROUND

Inborn errors of immunity (IEI) comprise more than 400 rare diseases with potential life-threatening conditions. Clinical manifestations and genetic defects are heterogeneous and diverse among populations. Here, we aimed to characterize the clinical, immunologic, and genetic features of Thai pediatric patients with IEI. The use of whole-exome sequencing (WES) in diagnosis and clinical decision making was also assessed.

METHODS

Thirty six unrelated patients with clinical and laboratory findings consistent with IEI were recruited from January 2010 to December 2020. WES was performed to identify the underlying genetic defects.

RESULTS

The median age of disease onset was 4 months (range: 1 month to 13 years), and 24 were male (66.7%). Recurrent sinopulmonary tract infection was the most common clinical presentation followed by septicemia and severe pneumonia. Using WES, we successfully identified the underlying genetic defects in 18 patients (50%). Of the 20 variants identified, six have not been previously described (30%). According to the International Union of Immunological Societies (IUIS), 38.9% of these detected cases (7/18) were found to harbor variants associated with genes in combined immunodeficiencies with associated or syndromic features (Class II).

CONCLUSION

The diagnostic yield of WES in this patient cohort was 50%. Six novel genetic variants in IEI genes were identified. The clinical usefulness of WES in IEI was demonstrated, emphasizing it as an effective diagnostic strategy in these genetically heterogeneous disorders.