The Kleefstra Clinic at Boston Children’s Hospital

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IDefine's First Initiative

The Kleefstra Clinic at Boston Children's Hospital

Funding this clinic was IDefine's very first initiative — and today it's one of only a few clinics in the world built entirely around Kleefstra syndrome. Every visit combines expert clinical care with active research, so families get answers today while helping build answers for tomorrow.

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A Kleefstra Clinic physician listens to a young patient's heart during a visit
By the Numbers Research & Studies Meet the Team Know Before You Go Contact
The Kleefstra Clinic, By the Numbers
A snapshot of what this partnership has built since day one.
0
Unique patients seen
5
Peer-reviewed publications
3
Research studies, past & ongoing
14
Specialists on the clinical & research team
Research & Studies
The clinic isn't just seeing patients — it's actively defining what Kleefstra syndrome is, for the whole world.
Active Study

ACTION Initiative

A three-year longitudinal natural history study following participants ages 2–21 to map the full clinical, molecular, and neurodevelopmental spectrum of Kleefstra syndrome — and identify the biomarkers future clinical trials will need.

Learn more & enroll →
Completed Study

Circadian Biology of EHMT1 (Sleep Study)

Led by Dr. Jonathan Lipton and Dr. Joe Kossowsky, this study asked whether EHMT1 disrupts the body's sleep-wake clock before regression begins — tracing the link between circadian rhythm and the regression so many families see after puberty.

Read the story →
Published 2025

Disease Concept Model

Genetic counselor Kristen Connors interviewed 16 families and 2 clinicians to build the first patient- and caregiver-centered model of what Kleefstra syndrome actually looks like day to day — now shaping educational materials and future treatment targets.

Meet the researcher →
Published 2025

Novel Phenotypes & Genotype-Phenotype Correlations

The largest clinical cohort study of Kleefstra syndrome to date, led by Zoë Frazier and the clinic team — uncovering new phenotypes and connecting specific genetic changes to the symptoms they cause.

Read the paper →
  • Morison et al. (2024). Expanding the phenotype of Kleefstra syndrome: Speech, language and cognition in 103 individuals. Journal of Medical Genetics. DOI →
  • Rots et al. (2024). Comprehensive EHMT1 variants analysis broadens genotype-phenotype associations. American Journal of Human Genetics. DOI →
  • Vasireddi et al. (2024). Arrhythmias including atrial fibrillation and congenital heart disease in Kleefstra syndrome. Europace. DOI →
Moments from the Clinic
Real visits, real families — a look at what a day at the Kleefstra Clinic feels like.
A member of the research team sharing a warm moment with a young patient in the waiting room A young patient holding a 'Neuroscientist in Training' badge during a research visit A clinician sharing a laugh with a young patient during an exam
Meet the Team
The clinicians and researchers behind every visit.
Siddharth Srivastava, MD
Siddharth Srivastava, MD
Clinical Neurologist, Principal Investigator, KS Research
Anne O’Donnell, MD, PhD
Anne O’Donnell, MD, PhD
Clinical Geneticist
Max Horlbeck, MD, PhD
Max Horlbeck, MD, PhD
Clinical Geneticist
Muhammed Cagri Bayraktutan, MD
Muhammed Cagri Bayraktutan, MD
Research Fellow
Zoë Frazier, MS, CGC
Zoë Frazier, MS, CGC
Primary Research Genetic Counselor, KS Team
Jillian O’Toole, MS, CGC
Jillian O’Toole, MS, CGC
Primary Clinical Genetic Counselor, KS Team
Abigail Sveden, MS, CGC
Abigail Sveden, MS, CGC
Genetic Counselor, Assisting KS Research Efforts
Brynn Heslin, BS
Brynn Heslin, BS
Genetic Counseling Assistant, KS Clinical Coordination
Sophia Kim, BS
Sophia Kim, BS
Research Assistant, KS Research Efforts
Anne Fulton, MD
Anne Fulton, MD
Ophthalmologist
Kiran Maski, MD
Kiran Maski, MD
Neurologist, Sleep Medicine Expert
Sonia Ballal, MD
Sonia Ballal, MD
Gastroenterologist
Eliot Shearer, MD, PhD
Eliot Shearer, MD, PhD
Otolaryngologist
Tamar Katz, MD
Tamar Katz, MD
Psychiatrist
Know Before You Go
Everything a family needs to plan a visit — from what happens in the room to where to grab dinner after.
What to Expect
  • Visits can be virtual or in person — most families in the current ACTION Initiative come in for three annual visits.
  • Every visit includes neurobehavioral assessments; some families opt into extras like a research EEG, a blood sample, or a week wearing a Fitbit at home.
  • Before you arrive, the team will send a medical records release so they can pull in history from your local providers.
  • What to bring: insurance card, a current medication list, and any recent local specialist notes.
Parent Voices
"The first time I met this team, I knew they were who we needed to build around — the compassion, the care, the knowledge, the expertise, all in one room. Funding the Kleefstra Clinic was IDefine's very first initiative, and it's become everything we hoped it would be: a place where families don't just get answers, they get a team that treats their child like family."
— Geoff Rhyne, Founder, IDefine
"Meeting Dr. Sid was one of the best things we have done… all the people involved at Boston Children's went out of their way to make it a great experience for all of our family."
— Amy Allen, KS mom, describing her visit with her daughter, Molly
"My heart is full from everything and everyone today. Megan was made to feel comfortable by all. Very, very positive experience."
— Helen Tyler, KS mom, describing her visit with her daughter, Megan
Quote coming soon.
— A Kleefstra Clinic Family
Lodging & Accommodations
Yawkey Family Inn — $30/night241 Kent St., Brookline (0.6 mi). Individual rooms, shared kitchen & laundry, free shuttle. Part of BCH's Patient Family Housing Program.
The Bon — $75/night1260 Boylston St., Boston. Private kitchenette apartments, also through the Patient Family Housing Program.
Book family housing617-919-3456 · familyhousing@childrens.harvard.edu. Apply up to 4 months ahead.
Nearby hotels (ask for the BCH rate)Inn at Longwood (0.3 mi), Hilton Garden Inn (1 mi), Residence Inn by Marriott (0.7 mi).
Hotel & concierge help617-355-4626 · conciergeservices@childrens.harvard.edu
Things to Do Nearby
Isabella Stewart Gardner Museum & MFABoth an easy walk from the hospital — a nice reset between appointments.
Fenway ParkA few blocks away; tours run even when the Red Sox are out of town.
The Emerald Necklace & Back Bay FensGreen space right nearby for a walk or a picnic.
Public Garden, Swan Boats & the EsplanadeA short ride away — great for siblings along for the trip.
Where to Eat
Longwood GalleriaThe hospital's own food court, right on campus.
Kenmore Square & FenwayA wide range of family-friendly restaurants within walking distance.
Ask the Concierge desk617-355-4626 keeps an updated list of family favorites near the hospital.

Ready to Schedule a Visit or Join a Study?

Reach the Kleefstra Syndrome Clinic research team directly:

617-919-7370  ·  KleefstraSyndromeClinic@childrens.harvard.edu