Biochemistry and Molecular Biology
Penn State Science
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Santhosh Girirajan

Santhosh Girirajan

Main Content

  • Associate Professor of Biochemistry & Molecular Biology and
  • Associate Professor of Anthropology
205 A Life Sciences Building
University Park, PA 16802
Phone: (814) 865-0674


Research Interests

Genetics of neurodevelopmental disorders

Graduate Programs


Research Summary

The primary focus of my research is to discover and characterize genetic changes including genomic deletions and duplications and single nucleotide mutations contributing to neurodevelopmental disorders such as autism, developmental delay and congenital malformation.

I am particularly interested in untangling the genetic and phenotypic heterogeneity of neurodevelopmental disorders.  There is extensive genetic heterogeneity (i.e. more than one gene or genomic region implicated) for neurodevelopmental disorders such as autism and developmental delay suggesting a larger genetic target.  And, even among individuals carrying the same genetic variant, significant differences in the clinical presentation have been documented.  This has posed considerable challenges in understanding the role of discovered genetic variants in terms of disease causation, diagnosis and interpretation for management and treatment.  The function of these variants in the etiology and pathogenesis of neurodevelopmental disorders is unknown. I am interested in combining work on the discovery of genetic variants in children with disease with functional characterization using model organisms to map disease-associated pathways and finding vulnerable targets for therapy.  I also plan to develop novel methods to understand and characterize genes and gene products relevant to developmental processes.

Selected Publications

  • Girirajan S†, Johnson RL, Tassone F, Balciuniene J, Katiyar N, Fox K, Baker C, Srikanth A, Yeoh K-H, Khoo SJ, Nauth TB, Hansen R, Ritchie MD, Hertz-Picciotto I, Eichler EE, Pessah IN, Selleck SB. Global increases in both common and rare copy number load associated with autism. Human Molecular Genetics, 2013, Mar 27.corresponding author.
  • Girirajan S*, Dennis MY*, Baker C, Malig M, Coe BP, Campbell CD, Mark K, Vu TH, Alkan C, Cheng Z, Biesecker LG, Bernier R, and Eichler EE. Refinement and discovery of new hotspots of copy number variation associated with autism spectrum disorder. American Journal of Human Genetics, 2013 Feb 7;92(2):221-37. *contributed equally.
  • Girirajan S*, Rosenfeld JA*, Coe BP, Parikh S, Friedman N, Goldstein A, Filipink RA, McConnell JS, Angle B, Meschino WS, Nezarati M, Asamoah A, Jackson KE, Gowans GC, Martin JA, Penney LS, Martin DM, Raskin S, Leppig K, Thiese H, Smith R, Aberg E, Niyazov DM, Escobar LF, El-Khechen D, Johnson KD, Lebel RR, Siefkas K, Ball S, Shur N, McGuire M, Brasington CK, Spence JE, Martin LS, Clericuzio C, Ballif BC, Shaffer LG, Eichler EE. The Phenotypic Heterogeneity of Genomic Disorders and Multiple, Rare CNVs. New England Journal of Medicine, September 2012. *contributed equally

  • Girirajan S, Brkanac Z, Coe BP, Baker C, Vives L, Vu TH, Shafer N, Bernier R, Ferrero GB, Silengo M, Warren ST, Moreno CS, Fichera M, Romano C, Raskind WH, Eichler EE.  Relative burden of large CNVs on a range of neurodevelopmental phenotypes. PLoS Genetics Nov 7. 2011.
  • Vu T, Coccaro E, Eichler EE, Girirajan S†.  Genomic architecture of aggression: Rare CNVs in intermittent explosive disorder. Am J Med Genet B Neuropsychiatr Genet Aug 2. 2011. †corresponding author
  • Cooper GM*, Coe BP*, Girirajan S*, Rosenfeld JA, Vu TH, Baker C, Williams C, Stalker H, Hamid R, Hannig V, Abdel-Hamid H, Bader P, McCracken E, Niyazov D, Leppig K, Thiese H, Hummel M, Alexander N, Gorski J, Kussmann J, Shashi V, Johnson K, Rehder C, Ballif BC, Shaffer LG, Eichler EE.  A copy number variation morbidity map of developmental delay. Nature Genetics Aug 14. 2011. *contributed equally
  • Girirajan S*, Rosenfeld JA*, Cooper GM, [53 authors], King M-C, Shaffer LG, Eichler EE.  A recurrent 16p12.1 microdeletion supports a two-hit model for severe developmental delay. Nature Genetics 42:203–209, 2010. *contributed equally
  • Girirajan S, Elsea SH.  Abnormal maternal behavior, altered sociability, and impaired serotonin metabolism in Rai1-transgenic mice. Mammalian Genome 20:247–255, 2009.
  • Girirajan S, Elsea, SH.  Distorted Mendelian transmission as a function of genetic background in Rai1-haploinsufficient mice. European Journal of Medical Genetics 52:224–228, 2009.
  • Girirajan S*, Chen L*, Graves T, Marques-Bonet T, Ventura M, Fronick C, Fulton L, Rocchi M, Fulton R, Wilson RK, Mardis ER, Eichler EE.  Sequencing human-gibbon breakpoints of synteny reveals mosaic new insertions at rearrangement sites. Genome Research 19:178–190, 2009. *contributed equally
  • Girirajan S, Truong HT, Blanchard CL, Elsea SH.  A functional network module for Smith-Magenis syndrome. Clinical Genetics 75: 364–374, 2009.
  • Girirajan S*, Hauck PM*, Williams SR, Vlangos CN, Szomju BB, Solaymani-Kohal S, Mosier PD, McCoy KL, White KL, Elsea SH.  Tom1l2 hypomorphic mice exhibit increased incidence of infections and tumors and abnormal immunological response. Mammalian Genome 19:246–262, 2008. *contributed equally. Featured on the cover of the April 2008 issue.
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