Skip Navigation
Find a Doctor


Photo of Dr. Andrew S. McCallion, Ph.D.

Andrew S. McCallion, Ph.D.

Associate Professor of Molecular and Comparative Pathobiology


  • Associate Professor of Molecular and Comparative Pathobiology
  • Research Associate of Medicine

Centers & Institutes

  • Institute for Basic Biomedical Sciences
  • McKusick-Nathans Institute of Genetic Medicine

Research Interests

Transcriptional regulation in development and disease; Genetics of neurological, neuropsychiatric and neural-crest disorders; Genetics basis of congenital malformations


Dr. Andrew McCallion is an associate professor of molecular and comparative pathobiology at the Johns Hopkins University School of Medicine. His research focuses on applying functional genetics to human development and disease. Dr. McCallion was part of a research team at Johns Hopkins that identified the two genes that cause Hirschsprung disease, an inherited intestinal disorder.

His research focuses on making the connection between gene sequence (and variation therein) and phenotype through the integrated use of contemporary genomic strategies and model systems (mouse, zebrafish and cell culture).

Dr. McCallion received his B.Sc. in genetics from The Queen''s University of Belfast. He earned his Ph.D. in genetics from the University of Glasgow. He completed postdoctoral training at Case Western Reserve University Medical School.

Prior to joining Johns Hopkins, Dr. McCallion was a project leader and staff scientist at Neuropa Ltd. (UK), a biotech startup focused on drug target development for neurodegenerative disorders.

He is a member of the International Mammalian Genome Society, American Society of Human Genetics and Federation of American Societies for Experimental Biology. He serves on the editorial board of Genome Research, and is a Faculty of 1000 faculty member in genomics and genetics.


  • English


Member, International Mammalian Genome Society

Member, American Society of Human Genetics

Member, Federation of American Societies for Experimental Biology

Additional Resources +
  • Education +


    • Ph.D., University of Glasgow, Glasgow, Scotland, 1998, Genetics
    • B.Sc.(Hons), The Queen's University of Belfast, Belfast, United Kingdom, 1994, Genetics
  • Research & Publications +

    Research Summary

    Dr. McCallion's research focuses on the roles played by cis-regulatory elements (REs) in controlling the timing, location and levels of gene activation (transcription). However, the biological relevance of non-coding sequences cannot be inferred by examination of sequence alone. Perhaps the most commonly used indicator of non-coding REs is evolutionary sequence conservation. Although conservation can uncover functionally constrained sequences, it cannot predict biological function, and regulatory function is not always confined to conserved sequences. At its simplest level, regulatory instructions are inscribed in transcription factor binding sites (TFBS) within REs. Yet, while many TFBS have been identified, TFBS combinations predictive of specific regulatory control have not yet emerged for vertebrates. Dr. McCallion and his team posit that motif combinations accounting for tissue-specific regulatory control can be identified in REs of genes expressed in those cell types. Their immediate goal is to begin to identify TFBS combinations that can predict REs with cell-specific biological control—a first step in developing true regulatory lexicons.

    Selected Publications

    1. Maragh S, Miller RA, Bessling SL, McGaughey DM, Wessels MW, de Graaf B, Stone EA, Bertoli-Avella AM, Gearhart JD, Fisher S, McCallion AS. "Identification of RNA binding motif proteins essential for cardiovascular development." BMC Dev Biol. 2011 Oct 19;11:62. doi: 10.1186/1471-213X-11-62.
    2. Stine ZE, McGaughey DM, Bessling SL, Li S, McCallion AS. "Steroid hormone modulation of RET through two estrogen responsive enhancers in breast cancer." Hum Mol Genet. 2011 Oct 1;20(19):3746-56. doi: 10.1093/hmg/ddr291. Epub 2011 Jul 7.
    3. Taher L, McGaughey DM, Maragh S, Aneas I, Bessling SL, Miller W, Nobrega MA, McCallion AS, Ovcharenko I. "Genome-wide identification of conserved regulatory function in diverged sequences." Genome Res. 2011 Jul;21(7):1139-49. doi: 10.1101/gr.119016.110. Epub 2011 May 31.
    4. Antonellis A, Dennis MY, Burzynski G, Huynh J, Maduro V, Hodonsky CJ, Khajavi M, Szigeti K, Mukkamala S, Bessling SL, Pavan WJ, McCallion AS, Lupski JR, Green ED; NISC Comparative Sequencing Program. "A rare myelin protein zero (MPZ) variant alters enhancer activity in vitro and in vivo." PLoS One. 2010 Dec 16;5(12):e14346. doi: 10.1371/journal.pone.0014346.
    5. Noonan JP, McCallion AS. "Genomics of long-range regulatory elements." Annu Rev Genomics Hum Genet. 2010;11:1-23. doi: 10.1146/annurev-genom-082509-141651. Review.


    As part of a functional genetic laboratory, Dr. McCallion and his researchers develop and implement assays to rapidly determine the biological relevance of sequence elements within the human genome and the pathological relevance of variation therein. In recent years, they have developed a highly efficient reporter transgene system in zebrafish that can accurately evaluate the regulatory control of mammalian sequences, enabling characterization of reporter expression during development at a fraction of the cost of similar analyses in mice. They employ a range of strategies in model systems (zebrafish and mice), as well as analyses in the human population, to illuminate the genetic basis of disease processes. Their long-term objective is to use these approaches in contributing to improved diagnostic, prognostic and ultimately therapeutic strategies in patient care.

    CORE Facilities

    Phenotyping (and Pathology) Core (Phenocore)

  • Academic Affiliations & Courses +
  • Activities & Honors +


    Faculty of 1000, Genomics and Genetics

    Professional Activities

    Editorial board, Genome Research, 2006 - present

    Rodent Advisory Committee, Johns Hopkins University

    Rodent Phenotyping CORE committee, Johns Hopkins University

  • Videos & Media +
  • Events +
  • Contact & Locations +


    • Molecular and Comparative Pathobiology
    • Medicine

Is This You? Edit Profile


© The Johns Hopkins University, The Johns Hopkins Hospital, and Johns Hopkins Health System. All rights reserved.

Privacy Policy and Disclaimer