Care
For Clinicians
ZTTK syndrome is a rare neurodevelopmental disorder caused by heterozygous loss-of-function variants in the SON gene (21q22.11).
Most variants are de novo — not inherited from either parent. The disorder was first described in 2016 following the identification of pathogenic SON mutations by Dr. Erin Ahn's research group in collaboration with clinical geneticists across the US and Europe.
Clinicians evaluating patients with intellectual disability, global developmental delay, and multi-system involvement should consider SON gene testing as part of the diagnostic workup. Severity and combination of features vary significantly between individuals.
Clinical Resources
- GeneReviews
Peer-reviewed NCBI entry — trusted clinical reference for geneticists and genetic counselors.
- Standard of Care Considerations
Draft co-developed with families — recommended clinical care strategies for ZTTK syndrome. Contact the foundation for access.
Resource inquiries: sboyle@zttk.org
Clinical Features by System
The following systems are commonly involved. Periodic re-evaluation is recommended even when initial assessments are normal, as presentation evolves with age.
Neurology
Brain abnormalities, epilepsy, global developmental delay, intellectual disability, autism-like features
Gastroenterology
Feeding difficulties, GERD, failure to thrive, intestinal complications
Ophthalmology
Cortical visual impairment, strabismus, vision loss
Immunology
Low vaccine response, immune deficiency, increased infection susceptibility
Cardiology
Heart defects, arrhythmias, valve abnormalities
Craniofacial
Cleft palate, laryngeal clefts, facial asymmetry
ENT
Repeated infections, hearing loss, swallowing difficulties
Endocrinology
Growth issues, thyroid disease, metabolic abnormalities
Hematology
Abnormal blood counts, clotting issues
Orthopedics
Scoliosis, hypermobility, mobility equipment needs
Pulmonology
Respiratory infections, airway issues
Urology
Ureter reflux, kidney complications
Dermatology
Eczema, nail dysplasia, infection susceptibility
Less Common Features
Specialist Involvement
Due to the multi-system nature of ZTTK syndrome, a coordinated multidisciplinary approach is recommended. The foundation advises involvement from specialists across neurology, genetics, gastroenterology, ophthalmology, immunology, cardiology, ENT, endocrinology, hematology, orthopedics, pulmonology, urology, and dermatology — with periodic re-assessment as the child grows, particularly in systems initially assessed as normal. ZTTK Ambassadors are available to assist families in coordinating specialist appointments.
Clinical Advisory Board
The ZTTK Clinical Advisory Board convenes clinicians who see ZTTK patients via regular Zoom meetings to gather symptom data, compare treatment approaches, and identify unmet research needs.
If you treat ZTTK patients and are interested in collaborating, the foundation welcomes your participation. A brief clinician survey (~10 minutes) helps the foundation understand the treating clinician community.
Clinician Contacts
Seeing a ZTTK Patient?
The foundation connects clinicians with family support resources and research opportunities. If you have questions about a patient or want to contribute to our growing clinical knowledge base, reach out directly.
Connect With the Foundation