Tuuli Lappalainen, PhD

Principal Investigator  

Tuuli Portrait-8648_smallTuuli Lappalainen is a Junior Investigator and Core Member at the New York Genome Center. She holds a joint appointment as an Assistant Professor in the Department of Systems Biology at Columbia University.

Her research focuses on functional genetic variation in human populations and its contribution to traits and diseases. She has pioneered the intergration of large-scale genome and transcriptome sequencing data to understand how genetic variation affects gene expression, providing insight to cellular mechanisms underlying genetic risk for disease.

Tuuli received her PhD from University of Helsinki, Finland in 2009, followed by postdoctoral research at University of Geneva, Switzerland with Manolis Dermitzakis and at Stanford University with Carlos Bustamante. She has made an important contribution to several international research consortia in human genomics, including the 1000 Genomes Project and the Genotype Tissue Expression (GTEx) Project, and led the RNA-sequencing work of the Geuvadis Consortium.

In addition to her work in genomics, Tuuli is also interested in scientific journalism, and has written newspaper articles and columns for Finnish newspapers. In her (limited…) free time, she enjoys contemporary art, sports, reading, cooking, and traveling.

Curriculum Vitae 04/2017

Elsewhere in the web

Selected publications

# Corresponding author   * Equal contribution

Ana Vasileva, PhD

Senior Staff Scientist in Molecular Biology

DSC_5682retouchedAna Vasileva works as a Senior Staff Scientist in the Lappalainen lab. She is now setting up the wetlab of the research group, and she oversees molecular and cell biology research in the Lappalainen lab. She will also participate in project design and grant writing.

Ana got her PhD at ICGEB and Osaka University on strategies for optimization of HBsAg expression in Pichia pastoris under the direction of Dr. Navin Khanna, and she did postdoctoral work woth Prof. Rolf Jessberger at Mount Sinai School of Medicine in New York where she carried out a project aimed at deciphering the mechanisms of gene targeting by recombinant adeno-associated virus in human cells. This effort extended in collaborations with laboratories focusing on correcting mutations in patient-specific iPS cells. It was during this time that she developed her ongoing interest in stem cell biology and began to study the unique niche of germ stem cells. Ana used NGS to compare piRNAs in wild type and Tdrd6-deficient germ cells. She continued to study the germ cell niche under the mentorships of Professor Debra Wolgemuth at Columbia University, specifically utilizing conditional mutant mouse strains to investigate the role of essential cell cycle genes in spermatogenesis.

Selected publications

  • Vasileva, A., Linden, R.M. and Jessberger, R. (2006) Homologous recombination is required for AAV-mediated gene targeting. Nucleic Acids Research 34(11), 3345-60.
  • Vasileva, A. and Jessberger, R. (2005) Precise Hit: adeno-associated virus in gene targeting. Nat. Rev. Microbiol. 3, 837-47.

Stephane Castel, PhD

Postdoctoral Researcher

stephaneStephane is a genomics based post-doctoral researcher in the Lappalainen Lab. Broadly he is interested in understanding how the genome is interpreted through transcription to produce complex phenotypes, which can be associated with disease. He obtained his PhD from Cold Spring Harbor Laboratory studying the interplay between transcription regulation by RNAi and DNA replication using high-throughput sequencing techniques in Robert Martienssen’s lab. He completed his BSc in Molecular Biology and Genetics at the University of Guelph in Canada, and is a native of Toronto.

Selected publications

  • Castel, S.E., Ren, J., Bhattacharjee, S., Chang, A.-Y., Sánchez, M., Valbuena, A., Antequera, F., and Martienssen, R.A. (2014). Dicer Promotes Transcription Termination at Sites of Replication Stress to Maintain Genome Stability. Cell 159, 572–583.
  • Castel, S.E., and Martienssen, R.A. (2013). RNA interference in the nucleus: roles for small RNAs in transcription, epigenetics and beyond. Nat Rev Genet 14, 100–112.
  • Zaratiegui, M., Castel, S.E., Irvine, D.V., Kloc, A., Ren, J., Li, F., de Castro, E., Marín, L., Chang, A.-Y., Goto, D., et al. (2011). RNAi promotes heterochromatic silencing through replication-coupled release of RNA Pol II. Nature 479, 135–138.

Pejman Mohammadi, PhD

Postdoctoral Researcher
Pejman2 Pejman Mohammadi joined Lappalainen lab at the beginning of 2015. He is a machine learner/computational biologist by training; having developed integrative models for fusing multiple datatypes, he is working on the genomics of complex diseases and primarily Rheumatoid Arthritis here at NYGC.

Pejman was born and raised in Isfahan, and obtained his BSc. degree from the Isfahan University of Technology in Software engineering. In 2008 he joined the Finnish centre of Excellence in Adaptive informatics research where he was baptised as Bayesian Orthodox. He obtained his MSc. in computer science and bioinformatics from Aalto School of Sciences in Helsinki. In 2010 he moved on to Switzerland to join the the Department of Biosystems Science and Engineering at ETH Zurich where he obtained his PhD. in computational biology of HIV in 2014.

Research Interests

    • Integrative analysis of biological systems, and regularized inference
    • Statistical machine learning and Bayesian data analysis
    • Computational immunology and auto-immune disorders
    • Computational design of synthetic biological networks

Publications on Google Scholar:

Sarah Kim-Hellmuth, MD, PhD

Postdoctoral Researcher
SarahSarah Kim-Hellmuth is a Postdoctoral Research Scientist in the Lappalainen lab. She is interested in human genetic variation and its effects on cellular functions linked to infectious and autoimmune disease.
Sarah studied Medicine in Munich, Germany and obtained her doctoral degree in Immunology in Veit Hornung’s lab, focusing on the recognition of microbial DNA by pattern recognition receptors. During her residency in Human Genetics at the University of Bonn she pursued her research interest both in immunology and human genetics by investigating expression quantitative trait loci (eQTLs), which underpin innate immune responses, and provide mechanistic insights to complement genome-wide association studies.


Google Scholar


Margot Brandt, BSc

PhD Student
MargotMargot is a graduate student in the lab from the Integrated Program in Cellular, Molecular and Biomedical Sciences at Columbia University. Before coming to Columbia she worked as a technician in Leonard Zon’s lab at Harvard Medical School using zebrafish as a model for investigating the molecular mechanisms of hematopoietic stem cell differentiation and self renewal. She earned her bachelor’s degree in biology from Wake Forest University where she did research in evolutionary genetics.

Elise Flynn, BSc

PhD Student

IMG_0780 (3)
Elise is a PhD student in the Systems Biology Program at Columbia University. She is interested in integrating -omics and other biological data to understand how perturbations in the genome and cell environment affect phenotype and disease. As a post-baccalaureate fellow with the NIH Undiagnosed Diseases Program, Elise researched and developed bioinformatic methods to study rare diseases. She earned her bachelor’s degree in biochemistry at St. Mary’s College of Maryland, where she did research in behavioral neuroscience. Outside of the lab, Elise is the Social Outreach chair of the Women in Science at Columbia group and the co-director of the Science Matters Research Internship program.

Paul Hoffman, BSc

Bioinformatics Analyst

Paul is a bioinformatics analyst, shared jointly with Rahul Satija’s lab. Before this position, he was a bioinformatics specialist for Peter Morrell at the University of Minnesota Agronomy Department. While there, he worked on finding the physical location of SNP markers on the barley genome, helped identify mutations that are important in cold tolerance in barley, and started asking how different motifs in genomic DNA influence point mutations in soybean. Paul earned his Bachelor’s degree in Microbiology from the University of Minnesota.

Selected publications

  • Durvasula A, Hoffman PJ, Kent TV, Liu C, Kono TJY, Morrell PL, Ross‐Ibarra J, angsd‐wrapper: utilities for analysing next‐generation sequencing data. Molecular Ecology Resources, August 2016. 16 (6): 1449-1454.
  • Kono TJY, Fu F, Mohammadi M, Hoffman PJ, Liu C, Stupar RM, Smith KP, Tiffin P, Fay JC, Morrell PL. The role of deleterious substitutions in crop genomes. Molecular Biology and Evolution. June 2016. 33 (9): 2307-2317

Erica Bertisch, BSc

Executive Assistant for Faculty

Erica Bertisch is the Executive Assistant for Faculty at the New York Genome Center, working for the Lappalainen and Pickrell labs. Previously, she was Executive Assistant to the President and Chief Executive Officer of The Leukemia & Lymphoma Society and assistant to the Executive Vice President, Founders Affiliate of the American Heart Association.  Erica is a graduate of Russell Sage College in Troy, New York, and makes her home in Brooklyn Heights.


Aaron Wolman, Associate Scientist I (2015-2017)

Nicholas Giangreco, Rotation student (2016)

Alejandra Cervera, Visiting student (2016)

Alexandre Yahi, Rotation student (2016)

Zach Baker, Rotation student (2015)

Ana Pascoini, Research Assistant (2014-2015)