[LIG4 syndrome: a report of four cases and literature review]

DNA ligase IV dificiency with elevated serum IgG levels suspected to have myelodysplastic syndrome: a case report

BACKGROUND

Ligase IV (LIG4) dificiency is a very rare clinical syndrome with around 50 cases reported to date. This syndrome is caused by biallelic pathogenic variants in the LIG4 gene, which cause DNA damage repair disorders, mainly manifesting as severe immunodeficiency.

CASE PRESENTATION

We report the case of a 15-month-old male child with pancytopenia, growth retardation, microcephaly, history of vaccine-related rubella, elevated immunoglobulin G, and decreased T- and B lymphocytes. Next-generation sequencing revealed LIG4 pathogenic genes and compound heterozygous mutations, namely the missense mutation c.833G > T (p.Arg278Leu) and deletion mutation c.1271_1275del (p.Lys424Argfs*20).

CONCLUSION

This case suggests that LIG4 dificiency can manifest not only as immunodeficiency but also with increased serum IgG levels and pancytopenia, which constitutes an additional clinical phenotype. Furthermore, this case suggests that LIG4 deficiency should be considered upon differential diagnosis of myelodysplastic syndrome in children.

LIG4 syndrome: clinical and molecular characterization in a Chinese cohort

Background

DNA Ligase IV (LIG4) syndrome is a rare disease with few reports to date. Patients suffer from a broad spectrum of clinical features, including microcephaly, growth retardation, developmental delay, dysmorphic facial features, combined immunodeficiency, and malignancy predisposition. There may be a potential association between genotypes and phenotypes. We investigated the characteristics of LIG4 syndrome in a Chinese cohort.

Results

All seven patients had growth restriction. Most patients (6/7) had significant microcephaly (< − 3 SD). Recurrent bacterial infections of the lungs and intestines were the most common symptoms. One patient had myelodysplastic syndromes. One patient presented with an inflammatory bowel disease (IBD)-like phenotype. Patients presented with combined immunodeficiency. The proportions of naïve CD4+ and naïve CD8+ T cells decreased notably in five patients. All patients harbored compound heterozygous mutations in the LIG4 gene, which consisted of a missense mutation (c.833G > T, p.R278L) and a deletion shift mutation, primarily c.1271_1275delAAAGA (p.K424Rfs*20). Two other deletion mutations, c.1144_1145delCT and c.1277_1278delAA, were novel. Patients with p.K424Rfs*20/p.R278 may have milder dysmorphism but more significant IgA/IgM deficiency compared to the frequently reported genotype p.R814X/p.K424Rfs*20. One patient underwent umbilical cord blood stem cell transplantation (UCBSCT) but died.

Conclusions

The present study reported the clinical and molecular characteristics of a Chinese cohort with LIG4 syndrome, and the results further expand the phenotypic and genotypic spectrum and our understanding of genotype-to-phenotype correlations in LIG4 syndrome.