Hal Dietz

Principal Investigator

My group has a 30 year commitment to the care and study of patients with heritable vascular connective tissue disorders that predispose to vascular dissection and/or rupture. These disorders include Marfan syndrome (MFS; mutations in FBN1), Loeys-Dietz syndrome (LDS; mutations in TGFBR1, TGFBR2, SMAD3, SMAD2, TGFB2, TGFB3), vascular Ehlers-Danlos syndrome (vEDS; mutations in COL3A1) and Sphrintzen-Goldberg syndrome (SGS; mutations in SKI). We have shown that the multisystem pathogenesis of each of these disorders relates to crosstalk between the transforming growth factor b (TGFb), angiotensin II (AngII) and mitogen-activated protein kinase pathways. I lead a multidisciplinary clinic focused on the diagnosis and chronic management of heritable connective tissue disorders, with an age range spanning from birth to late old age and nearly 1,000 patient visits per year. My research integrates clinical care, disease gene identification, mechanistic studies in animal models, natural history studies and treatment trials. I have had the honor of mentoring over 50 graduate students and emerging physician scientists and have trained over a dozen clinicians in a wide variety of disciplines who have dedicated their careers to people with vascular connective tissue disorders.

Debbie Churchill


Debbie has been doing the seemingly impossible task of scheduling everything the Dietz Lab needs smoothly and seamlessly for 12 years. She has a keen talent for cutting through the noise, and remains the most organized member of the lab. Debbie is undoubtedly one of the pillars of the Dietz lab, and the most capable person you'll find to judge any pie day contest. 

Our Lab Scientists

Sara Cooke

Lab Manager

Sara Cooke has been working to manage the Dietz lab for over 15 years. Beyond providing essential knowledge of the inner workings of critical lab processes, she has been an endless source of moral and personal support to the many people who have come through the lab. At tea time, she likes talking about her 7 lb dog Rufio, lifting people's spirits with the latest roundboys video, and doing it all while sipping Diet Coke.

Jefferson Doyle

Assistant Professor

Jefferson Doyle, M.D., Ph.D., M.H.S. specializes in genetic eye disorders. He is a pediatric ophthalmologist whose clinical focus includes the ocular manifestations of connective tissue disorders, pediatric cataracts and ectopia lentis, pediatric glaucoma and anterior segment dysgenesis, and pediatric retinal dystrophies. His main research focus is elucidating the molecular mechanisms driving disease progression in Marfan syndrome and other causes of genetically-induced high myopia, with the goal of developing novel treatment approaches to translate into human trials. He also has an interest in modifier gene identification and leveraging this information for therapeutic benefit. He is a faculty member in the Wilmer Eye Institute, the Department of Genetic Medicine (DGM) and the Cellular and Molecular Medicine (CMM) graduate training program at Johns Hopkins, and greatly enjoys teaching in both clinical and research realms. Interests outside work include flying, sailing and the Baltimore symphony.

Shira Ziegler

Chief Resident

Shira G. Ziegler, M.D., Ph.D. is currently the Johns Hopkins Genetics chief resident. She graduated from the Johns Hopkins University School of Medicine MD-PhD program in 2018. Her graduate research in Hal Dietz's laboratory elucidated the mechanisms underlying rare disorders of ectopic and vascular calcification and identified new treatment strategies. She then pursued dual residency training in pediatrics and medical genetics. Shira is now back in the Dietz laboratory and continues to investigate rare calcific disorders. She plans to combine her bench-to-bedside research on rare genetic conditions with clinical care. She enjoys mentoring trainees and teaching medical students and residents. When not busy in clinic or the laboratory, she loves hiking and sailing, and cheering for the Ravens and the Orioles.

Nicole Anderson

Postdoctoral Fellow

Nicole completed her PhD in the Dietz Lab in 2018. She loved it so much that she just couldn't leave and is still hanging around two years later. She loves running, cooking, the ocean, and hanging out with her big dog and two awesome daughters.

Emily Juzwiak

6th Year Graduate Student

Emily Juzwiak is a 4th year Cellular and Molecular Medicine PhD candidate in the Dietz lab. Her work focuses on understanding sexual dimorphism and the role of androgens in vascular Ehlers-Danlos syndrome. Prior to graduate school, Emily received a BS in Genetics and Molecular Genomics from Michigan State University. During tea time, she likes talking about funny pet stories, weekend plans, and restaurant recommendations.

Cassie Parks

5th Year Graduate Student

Cassie is an MD/PhD student in the Cellular and Molecular Medicine program, who is in her third year with the Dietz Lab studying genetic contributions to spinal CSF leaks and spontaneous intracranial hypotension. Cassie is originally from the Chicago suburbs and attended Washington University in St. Louis before doing a 2-year post-baccalaureate fellowship at the NIH. At tea time she likes to stretch because she's sore from weightlifting and show everyone pictures of her husky.

Our Clinical Team

Gretchen MacCarrick

Genetic Counselor

Gretchen MacCarrick is a board-certified genetic counselor in the Department of Genetic Medicine at the Johns Hopkins University. She has worked in the Cardiovascular Connective Tissue Clinic since 2001, with activities surrounding both patient care and clinical research initiatives. She is co-founder of the Loeys-Dietz Syndrome Foundation and passionate about resource access, education and advocacy for patients impacted by vascular conditions.  

Catherine Kashmer

Certified Physician Assistant

Catherine Kashmer has been within the Johns Hopkins system for the past 13 years, initially as a cardiac sonographer. She graduated from Towson University's Physician Assistant program in 2018 with a Master of Science, and soon after stepped into her current role in the Connective Tissue Disorders clinic.

Lab Alumni

Graduate Students

Manuel Seman-Senderos, Ph.D.

Current Position: Assistant Teaching Professor, Drexel University


Caitlin Bowen, M.D./Ph.D.

Current Position: Resident, Boston's Children's Hospital

2017 - 2020

Joseph Shin, M.D./Ph.D.

Current Position: Resident, Johns Hopkins

2015 - 2019

Adam Lee Johnson, M.D.

Current Position: Resident, Massachusetts General Hospital

2016 - 2017

Robert Wardlow, M.D./Ph.D

Current Position: Resident, University of Pennsylvania

2015 - 2018 

James Beckett, M.D./Ph.D.

Current Position: Resident, Johns Hopkins

2014 - 2018

Oscar Busnadiego Prieto, Ph.D.


Suha Bachir, M.D.

Current Position: Resident, University of Cincinnati

2012 - 2014

Benjamin Kang, Ph.D.

Current Position: Clinical Fellow, Emory University

2012 - 2017

Shira Ziegler, M.D./Ph.D.

Current Position: Resident, Johns Hopkins

2011 - 2017

Juan Calderon, Ph.D.

Current Position: Faculty of Medicine, University of Development, Centro de Genética y Genómica, (Chile)

2008 - 2014

Hamza Aziz, M.D.

 Current Position: Fellow, Surgery-Cardiac Surgery, Johns Hopkins

2008 - 2009

David Kim, Ph.D.

Current Position: Scientist, Blade Therapeutics, Inc.

2007 - 2015

Stefani Fontana, M.D./Ph,D.

Current Position: Resident, Mount Sinai Health System

2007 - 2013

Elizabeth Gerber, M.D./Ph.D.

Current Position: Resident, Johns Hopkins

2007 - 2013

Tammy Holm, M.D./Ph.D.

Current Position: Assistant Professor, University of Cincinnati 

2007 - 2009

Matthew Feldman, M.A.

Current Position: Communications Director, ZyMōt Fertility

2004 - 2011

Timothy Cooper, DVM, Ph.D.

Current Position: Assistant Professor, Hershey Medical Center College of Medicine

2004 - 2007

K.C. Kent, Ph.D.

2004 - 2012

Connie Ng (Hess), M.D.         

Current Position: Cardiologist, Colorado

2003 - 2004

Mark Awad, M.D./Ph.D.

Current Position: Assistant Professor, Harvard

2003 - 2006

Neda Sharifi, Ph.D. 

Current Position: Associate, Lawyer, Foley & Lardner LLP

2002 - 2007

Joshua T. Mendell, M.D./Ph.D.

Current Position: Professor and Vice-Chair, UT Southwestern Medical Center; Investigator, HHMI

1996 - 2004

Dan E. Arking, Ph.D.

Current Position: Professor, Johns Hopkins

1996 - 2002

Pamela A. Frischmeyer, M.D./Ph.D

Current Position: Chief, Food Allergy Research Unit, National Institute of Allergy and Infectious Diseases (NIAID)

1996 - 2001 

Erick Noensie, Ph.D.

Current Position: Health Care Analyst

1995 - 2000

Haley A. (Perlick) Laken, Ph.D.

Current Position: Vice President, Jounce Therapeutics, Inc.

1994 - 1999

Nancy L. Jensen Biery, Ph.D.

1993 - 1999

Zayd A. Eldadah, M.D./ Ph.D.

Current Position: Director of Cardiac Electrophysiology at MedStar Heart & Vascular Institute

1992 - 1996

Lab Alumni

Postdoctoral Fellows

Katelynn Owens

Current Position: Senior Research Scientist


Rebecca Sorber, M.D.

Current Position: Surgical Resident, Johns Hopkins


Guy Bar-Klein, Ph.D.

Current Position: Manager, R&D, Neurocentria


Ali Keramati, M.D.

Current Position: Clinical Fellow, Cardiology, Johns Hopkins


Varun Nagpal, Ph.D.

Current Position: Scientist, Cascadian Therapeutics, Inc.


Russell Gould, Ph.D.

Current Position, Scientist, Johnson & Johnson


Xiaoli Zhong, Ph.D.

Current Position: Assistant Professor, Nanjing Medical University


Jill Fahrner, M.D./Ph.D.

Current Position: Assistant Professor, Johns Hopkins


Alexander Doyle, M.D.

Current Position: Anesthesia Resident, The Royal London Hospital


Hans Bjornsson, M.D./Ph.D.

Current Position: Assistant Professor, Johns Hopkins,

Clinical Director, Landspitali University Hospital (Iceland)


Anthony Guerrerio, M.D./Ph.D.

Current Position: Assistant Professor, Johns Hopkins


Rosanne Rouf, M.D.

Current Position: Assistant Professor, University of Michigan


Elena Gallo MacFarlane, Ph.D.

Current Position: Assistant Professor, Johns Hopkins


Sarah J. Parker, Ph.D., M.S.

Current Position: Assistant Professor, Cedars-Sinai


Ari Zaiman, M.D./Ph.D.

Current Position: Medical Director of Pulmonary Medicine, GMBC


Mark Lindsay, M.D./Ph.D.

Current Position: Assistant Professor, Massachusetts General Hospital


David Loch, Ph.D.

Current Position: Senior Associate/Patent Attorney, Spruson & Ferguson, Australia


Christel van Erp, Ph.D. 

Current Position: Physiotherapist Brisbane, Australia


Benjamin Brooke, M.D.

Current Position: Chief, Division of Vascular Surgery, 

The University of Utah

2005 - 2011

Dongli Huang, Ph.D.

Current Position: Associate Professor, Medical College of Wisconsin

2005 - 2008

Jennifer Habashi, M.D.

Current Position: Assistant Professor, Johns Hopkins

2004 - 2007

Junji Chen, Ph.D.

Current Position: Research Scientist, Pharmaceutical International

2004 - 2008

Ronald Cohn, M.D.

Current Position: President, The Hospital for Sick Children 

2004 - 2006

Melissa Loscalzo, M.D

Current Position: Assistant Professor, Johns Hopkin's Medicine

2001 - 2004

Bart Loeys, M.D./Ph.D.

Current Position: Professor, University of Antwerp/Antwerp University Hospital, Belgium

2002 - 2005

Denise Goh, M.D.

Current Position: Khoo Teck Puat-National University Children's Medical Institute, National University Health System

2000 - 2002

Enid Neptune, M.D.

Current Position: Associate Professor, Johns Hopkins

1999 - 2002

Daniel P. Judge, M.D.

Current Position: Professor, Medical University of South Carolina

1998 - 2002

Jun Zhang, Ph.D.

Current Position: Associate Professor, Texas Tech University Health Sciences Center

1998 - 2002

Susan M. Medghalchi, Ph.D.

Current Position: Adjunct Professor of Biology, Stevenson University

1997 - 2000

Robert A. Montgomery, M.D./Ph.D.

Current Position: Professor, Director, NYU Langone Transplant Institute 

1995 - 1997

Lab Alumni

Lab Technicians and Gap Year Students

Zachary Burger

2018 - 2022

Sophie Zhang


Rustam Bagirzadeh

Current Position: Monk

2015 - 2019

Graham Rykiel

Current Position: Graduate Student

2014 - 2016

YiChun Chen

2008 - 2015