Large deletions and point mutations involving the dedicator of cytokinesis 8 (DOCK8) in the autosomal-recessive form of hyper-IgE syndrome

J Allergy Clin Immunol. 2009 Dec;124(6):1289-302.e4. doi: 10.1016/j.jaci.2009.10.038.

Abstract

Background: The genetic etiologies of the hyper-IgE syndromes are diverse. Approximately 60% to 70% of patients with hyper-IgE syndrome have dominant mutations in STAT3, and a single patient was reported to have a homozygous TYK2 mutation. In the remaining patients with hyper-IgE syndrome, the genetic etiology has not yet been identified.

Objectives: We aimed to identify a gene that is mutated or deleted in autosomal recessive hyper-IgE syndrome.

Methods: We performed genome-wide single nucleotide polymorphism analysis for 9 patients with autosomal-recessive hyper-IgE syndrome to locate copy number variations and homozygous haplotypes. Homozygosity mapping was performed with 12 patients from 7 additional families. The candidate gene was analyzed by genomic and cDNA sequencing to identify causative alleles in a total of 27 patients with autosomal-recessive hyper-IgE syndrome.

Results: Subtelomeric biallelic microdeletions were identified in 5 patients at the terminus of chromosome 9p. In all 5 patients, the deleted interval involved dedicator of cytokinesis 8 (DOCK8), encoding a protein implicated in the regulation of the actin cytoskeleton. Sequencing of patients without large deletions revealed 16 patients from 9 unrelated families with distinct homozygous mutations in DOCK8 causing premature termination, frameshift, splice site disruption, and single exon deletions and microdeletions. DOCK8 deficiency was associated with impaired activation of CD4+ and CD8+T cells.

Conclusion: Autosomal-recessive mutations in DOCK8 are responsible for many, although not all, cases of autosomal-recessive hyper-IgE syndrome. DOCK8 disruption is associated with a phenotype of severe cellular immunodeficiency characterized by susceptibility to viral infections, atopic eczema, defective T-cell activation and T(h)17 cell differentiation, and impaired eosinophil homeostasis and dysregulation of IgE.

Publication types

  • Research Support, N.I.H., Extramural
  • Research Support, Non-U.S. Gov't

MeSH terms

  • Child
  • Child, Preschool
  • Female
  • Genes, Recessive
  • Genome-Wide Association Study
  • Guanine Nucleotide Exchange Factors / genetics*
  • Haplotypes / genetics
  • Homozygote
  • Humans
  • Job Syndrome / genetics*
  • Job Syndrome / immunology
  • Job Syndrome / pathology
  • Lymphocyte Activation / genetics
  • Lymphocyte Activation / immunology
  • Male
  • Pedigree
  • Point Mutation*
  • Polymorphism, Single Nucleotide
  • Sequence Deletion*
  • T-Lymphocytes / immunology

Substances

  • DOCK8 protein, human
  • Guanine Nucleotide Exchange Factors