Dr. Claassen received his undergraduate degree in Biology/Biochemistry from Carleton College in 2002, and then completed a post-baccalaureate research year at NIH in a molecular genetics lab prior to enrolling in the combined MD/PhD program at the University of Nebraska Medical Center.  While in training, he developed an interest in genetic syndromes and dysmorphology, and he completed his PhD in the Cancer Research Graduate Program studying DNA repair, mechanisms of trinucleotide repeat instability, and regulation of pluripotency.  He completed his internship and residency in Pediatrics in the UT Southwestern/Children’s Medical Center program, graduating in 2014.  He will be starting his fellowship in pediatric hematology and oncology at St. Jude Children’s Research Hospital starting in July 2015.


Graduate School University of Nebraska Medical Center Cancer Research Graduate Program (2009), Research
Medical School University of Nebraska College of Medicine (2011)
Residency UT Southwestern Medical Center (2014), Pediatrics

Specialty Areas

Research Interest

  • DNA repair


Featured Publications LegendFeatured Publications

ROCK inhibition enhances the recovery and growth of cryopreserved human embryonic stem cells and human induced pluripotent stem cells.
Claassen DA, Desler MM, Rizzino A Mol. Reprod. Dev. 2009 Aug 76 8 722-32
Regulation of the Nanog gene by both positive and negative cis-regulatory elements in embryonal carcinoma cells and embryonic stem cells.
Boer B, Cox JL, Claassen D, Mallanna SK, Desler M, Rizzino A Mol. Reprod. Dev. 2009 Feb 76 2 173-82
Expansions of CAG.CTG repeats in immortalized human astrocytes.
Claassen DA, Lahue RS Hum. Mol. Genet. 2007 Dec 16 24 3088-96
Detection of hemizygosity in Hermansky-Pudlak syndrome by quantitative real-time PCR.
Griffin AE, Cobb BR, Anderson PD, Claassen DA, Helip-Wooley A, Huizing M, Gahl WA Clin. Genet. 2005 Jul 68 1 23-30
Cellular, molecular and clinical characterization of patients with Hermansky-Pudlak syndrome type 5.
Huizing M, Hess R, Dorward H, Claassen DA, Helip-Wooley A, Kleta R, Kaiser-Kupfer MI, White JG, Gahl WA Traffic 2004 Sep 5 9 711-22
Hermansky-Pudlak syndrome type 4 (HPS-4): clinical and molecular characteristics.
Anderson PD, Huizing M, Claassen DA, White J, Gahl WA Hum. Genet. 2003 Jul 113 1 10-7

Honors & Awards

  • Director's Distinguished Service Award
    NHGRI, NIH (2003)

Professional Associations/Affiliations

  • American Academy of Pediatrics
  • Dallas County Medical Society
  • Texas Medical Association