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

Karin R. Engelhardt, Dra ∗, Sean McGhee, MDb ∗, Sabine Winkler, MSca, Atfa Sassi, PhDc, Cristina Woellner, MSca, Gabriela Lopez-Herrera, PhDa, Andrew Chenb, Hong Sook Kim, PhDb, Maria Garcia Lloret, MDb, Ilka Schulze, MDd, Stephan Ehl, MDd, Jens Thiel, MDd, Dietmar Pfeifer, Dre, Hendrik Veelken, MDe, Tim Niehues, MDf, Kathrin Siepermann, MDf, Sebastian Weinspach, MDg, Ismail Reisli, MDh, Sevgi Keles, MDh, Ferah Genel, MDi, Necil Kutuculer, MDj, Yıldız Camcıoğlu, MDk, Ayper Somer, MDl, Elif Karakoc-Aydiner, MDm, Isil Barlan, MDm, Andrew Gennery, MDn, Ayse Metin, MD, PhDo, Aydan Degerliyurt, MDo, Maria C. Pietrogrande, MDp, Mehdi Yeganeh, MDq, Zeina Baz, MDr, Salem Al-Tamemi, MDs, Christoph Klein, MD, PhDt, Jennifer M. Puck, MDu, Steven M. Holland, MDv, Edward R.B. McCabe, MD, PhDw, Bodo Grimbacher, MDa ∗∗

, Talal A. Chatila, MD, MScb ∗∗

Received 23 September 2009; received in revised form 22 October 2009; accepted 26 October 2009.

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 Th17 cell differentiation, and impaired eosinophil homeostasis and dysregulation of IgE.

Key words: Autosomal recessive hyper-IgE syndrome, human gene mutation, DOCK8, primary immunodeficiency, molluscum contagiosum, recurrent infection, T cells, TH17 cells, eosinophils, IgE regulation, copy number variations, genomic deletions

a Department of Immunology and Molecular Pathology, Royal Free Hospital and University College London, London, UK

b Division of Immunology, Allergy and Rheumatology, Department of Pediatrics, David Geffen School of Medicine at the University of California at Los Angeles, Los Angeles, Calif

c Laboratoire d'immunologie, vaccinologie et génétique moléculaire, Institut Pasteur de Tunis, Tunisia

d Center of Chronic Immunodeficiency, University Medical Center Freiburg, Freiburg, Germany

e Department of Hematology/Oncology, University Medical Center Freiburg, Freiburg, Germany

f HELIOS Klinikum Krefeld, Zentrum für Kinder-und Jugendmedizin, Krefeld, Germany

g Department of Pediatric Oncology, Hematology and Clinical Immunology, Center of Child and Adolescent Medicine, Heinrich-Heine-University Dusseldorf, Duesseldorf, Germany

h Selcuk University, Division of Pediatric Allergy and Immunology, Konya, Turkey

i Behcet Uz State Hospital Division of Pediatric Immunology, Izmir, Turkey

j Ege University Faculty of Medicine, Department of Pediatrics, Izmir, Turkey

k Division of Pediatric Allergy-Immunology and Infectious Diseases, Cerrahpasa Medical Faculty, Istanbul University, Istanbul, Turkey

l Division of Infectious Diseases and Immunology, Istanbul Medical Faculty, Istanbul University, Istanbul, Turkey

m Division of Pediatric Allergy and Immunology, Marmara University, Istanbul, Turkey

n Institute of Cellular Medicine, Child Health, University of Newcastle Upon Tyne, Newcastle upon Tyne, UK

o Pediatric Immunology Unit, SB Ankara Diskapi Children's Hospital, Ankara, Turkey

p Department of Maternal and Pediatric Sciences, University of Milan, Fondazione IRCCS Policlinico Milano, Milan, Italy

q Immunology Asthma and Allergy Research Institute, Children's Medical Center, Tehran University of Medical Sciences, Tehran, Iran

r Department of Pediatrics, St George Hospital University Medical Center, Beirut, Lebanon

s Department of Pediatrics, Sultan Qaboos University, Muscat, Oman

t Department of Pediatric Hematology/Oncology, Hannover Biomedical Research School, Hannover, Germany

u University of California, San Francisco, Calif

v Laboratory of Clinical Infectious Diseases, NIAID, NIH, Bethesda, Md

w Departments of Pediatrics, Human Genetics, and Bioengineering, and the Center for Society and Genetics, UCLA, Los Angeles, Calif

Reprint requests: Bodo Grimbacher, MD, Department of Immunology and Molecular Pathology, Royal Free Hospital and University College London, Pond Street, London NW3 2QG, United Kingdom.

Talal Chatila, MD, MSc, Division of Pediatric, Immunology, Allergy and Rheumatology, MDCC 12-430, Mail Code 175217, David Geffen School of Medicine, University of California at Los Angeles, 10833 Le Conte Avenue Los Angeles, CA 90095-1752.

Supported by National Institutes of Health grants 5R01AI065617 and 1R21AI087627 to T.C. and by the EU Marie-Curie grant MEXT-CT-2006-042316 and the European Community's 7th Framework Programme FP7/2007-2013 grant EURO-PADnet HEALTH-F2-2008-201549 to B.G.

Disclosure of potential conflict of interest: K. R. Engelhardt, S. Winkler, and G. Lopez-Herrera are employed on a research grant from the European Union (EU Marie-Curie grant). S. McGhee is a board member of Madison's Foundation. E. R. B. McCabe has received research support from the National Institutes of Health/National Human Genome Research Institute. B. Grimbacher (EU Marie-Curie grant) has received research support from the European Union and the Primary Immunodeficiency Association. The rest of the authors have declared that they have no conflict of interest.

∗ These authors contributed equally to this work.

∗∗ These authors contributed equally to this work.

PII: S0091-6749(09)01604-2

doi:10.1016/j.jaci.2009.10.038

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