Xiao P Peng, M.D., Ph.D.

Headshot of Xiao P Peng
  • Director, Inborn Errors of Immunity Clinic
  • Assistant Professor of Genetic Medicine

Languages: English, Chinese, French


Diagnostic Medicine, Genetic Diseases, Human Genetics, Immune Dysregulation Disorders, Medical Genetics-Inherited Disorders, Primary Immunodeficiency Diseases ...read more


Xiao Peng is currently Assistant Professor of Genetic Medicine and Director of the Inborn Errors of Immunity clinic at Hopkins, where she completed a combined residency in Pediatrics and Medical Genetics, followed by a year as T32-supported Research Fellow and Chief Resident in Genetics.

Xiao graduated in 2005 with a B.S. in Chemistry with Honors from Caltech and then worked for 2 years as an HHMI-sponsored research assistant in the Cancer Genomics program at the Broad Institute of Harvard/MIT. During this time, she participated in many published basic science and translational medicine projects, spanning the range from DNA replication to transcriptomics to the role of tyrosine kinases in cancer therapy to the understanding of miRNA function in hematopoietic development. Here, she was also first exposed to the magic of genomics, witnessing first-hand the advent of massively parallel sequencing technologies.

She graduated with an MD-PhD from Weill Cornell/Rockefeller/Memorial Sloan-Kettering Tri-Institutional MD-PhD Program in 2017, where she continued to pursue her interest in fundamental biological processes by studying the interface between DNA replication/repair, transcriptional regulation and post-translational protein modification pathways. She also published additional research in the realms of immunology and developmental gene regulation.

Since being at Hopkins, she has adapted her basic science background to an understanding of human disease. Her abiding interests in genome maintenance, gene regulation and host-pathogen evolution have synergistically converged with her passion for the care of patients with disorders of immunity and hematopoiesis.

Xiao continues to spearhead the effort to bring more patients with suspected inborn errors of immunity (IEIs) to molecular diagnosis, co-authoring multiple book chapters, several key reviews and papers in the process. She is very excited to work with so many great colleagues as a founding member of the Center for Immune-Related Disorders - to help build better protocols, resources and infrastructure for diagnosis and management of IEI patients, while carving out new paths in diagnosis and treatment on the research side.

She is equally passionate about the need to dedicate time to teaching, mentoring, and outreach. She has taught and continues to teach courses on immunology, genetics/genomics and their interface to PhD and MD students, as well as to residents and fellows across many departments. She acts as the clinical liaison between the Johns Hopkins Genomics lab and hospital providers in need of molecular diagnostic testing.

Finally, Xiao feels very lucky to be a citizen of the world and to have had seminal clinical experiences with the Indian Health Service and abroad. She remains a member of the research genetics team at the University of Freiburg's Center for Chronic Immunodeficiency and collaborates with many excellent researchers and clinicians around the world. And she is always happy to talk about wine with anyone interested...

...read more


  • Director, Inborn Errors of Immunity Clinic
  • Clinical Advisor, Johns Hopkins Genomics DNA Diagnostics Lab
  • Assistant Professor of Genetic Medicine

Departments / Divisions

Centers & Institutes



  • MD; Weill Cornell Medicine (2017)


  • Pediatrics; Johns Hopkins University School of Medicine (2021)


  • Pediatric Genetics; Johns Hopkins University School of Medicine (2022)

Board Certifications

  • American Board of Medical Genetics and Genomics (Clinical Genetics and Genomics (MD)) (2021)
  • American Board of Pediatrics (Pediatrics) (2021)

Research & Publications

Selected Publications

View all on PubMed

Peng XP, Caballero-Oteyza A, Grimbacher B. Common Variable Immunodeficiency: More Pathways than Roads to Rome. Annu Rev Pathol. 2022 Oct 20. doi:10.1146/annurev-pathmechdis-031521-024229. Epub ahead of print

Peng XP, Schnappauf O, de Jesus AA, Aksentijevich I. Chapter: Autoinflammatory Disorders. Section Editor: Abraham R. Section: Inborn Errors of Immunity. Manual of Molecular and Clinical Laboratory Immunology, 9th Edition. Washington, D.C., ASM/Wiley. In press

Meng X, Wei L, Peng XP, Zhao X. Sumoylation of the DNA polymerase ε by the Smc5/6 complex contributes to DNA replication. PLoS Genet. 2019 Nov 25;15(11):e1008426

Peng XP, Lim S, Li S, Marjavaara L, Chabes A, Zhao XL. Acute Smc5/6 depletion reveals its primary role in rDNA replication by restraining recombination at fork pausing sites. PLoS Genet. 2018 Jan 23; 14(1): e1007129

Zheng Y, Josefowicz S, Chaudhry A, Peng XP, Forbush K, Rudensky AY. Role of conserved non-coding DNA elements in the Foxp3 gene in regulatory T cell fate. Nature. 2010 Feb 11;463(7282):808-12

Contact for Research Inquiries

Johns Hopkins University SOM Dept of Genetic Medicine
600 N. Wolfe Street
Blalock 1008
Baltimore, MD 21287 map

Academic Affiliations & Courses

Courses and Syllabi

  • Systems, Genes, Mechanisms of Disease - Immunity
    JHU SOM Dept of Genetic Medicine
  • Transition to the Wards - “Genetics in Action”
  • TIME Course: Genomics 101
  • Translational Medicine - Immunology
  • PRECEDE Session for Pediatric Clerkship - Genetics Evaluation in Pediatrics
  • Current Topics in Clinical Genetics - Inborn Errors of Immunity

Activities & Honors


  • Physician Scientist Training Program Research Microgrant Award, JHU School of Medicine, 2022
  • Margaret Nielsen Fellowship in Genetic Medicine, Johns Hopkins Dept of Genetic Medicine, 2020
  • Jay Lawrence Award for Clinical Proficiency in Infectious Diseases, Weill Cornell Medicine, 2017
  • Weill Cornell International Health Grant in Infectious Disease/Tropical and Travel Medicine, Weill Cornell Medicine/Ludwig-Maximilians-Universität, 2017
  • Primary Immunodeficiency Summer School Participant, Clinical Immunological Society, 2021 - 2021
  • Paul & Daisy Soros Fellowship for New Americans, Paul & Daisy Soros Foundation, 2011 - 2013
  • Axline Merit Scholarship, California Institute of Technology, 2001 - 2005


  • Clinical Immunological Society

Professional Activities

  • Antibody Deficiencies Variant Curation Expert Panel, ClinGen

Videos & Media

Lectures and Presentations

  • Inborn Errors of Immunity - Genetic Pitfalls and Paradigms
    Lecture/Seminar, Quarterly Meeting (04/21/2021)
    Baltimore Washington Genetics Group

Patient Ratings & Comments

The Patient Rating score is an average of all responses to physician related questions on the national CG-CAHPS Medical Practice patient experience survey through Press Ganey. Responses are measured on a scale of 1 to 5, with 5 being the best score. Comments are also gathered from our CG-CAHPS Medical Practice Survey through Press Ganey and displayed in their entirety. Patients are de-identified for confidentiality and patient privacy.

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