ZHU-TOKITA-TAKENOUCHI-KIM SYNDROME
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ALTERNATE NAMES
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Brain Malformations-Musculoskeletal Abnormalities-Facial Dysmorphism-Intellectual
Disability Syndrome; ZTTK Syndrome
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DESCRIPTION
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Zhu-Tokita-Takenouchi-Kim (ZTTK) syndrome is a rare genetic disorder characterized by a combination of neurological,
developmental, and physical abnormalities. ZTTK syndrome is caused by a change in
the SON gene at conception. Most individuals with ZTTK syndrome have a new (de novo) variant in the SON gene that was not inherited from either biological parent. This condition typically
affects multiple body systems; however, it can affect each individual differently
depending on where the change is located on the SON gene.
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DIAGNOSTIC TESTING, PHYSICAL FINDINGS, AND ICD-9-CM/ICD-10-CM CODING
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Diagnostic testing: ZTTK syndrome is diagnosed by:
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A detailed patient and family history;
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Magnetic resonance imaging (MRI) of the brain;
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Electroencephalogram (EEG); and
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Whole exome sequencing (WES).
Molecular genetic testing such as chromosomal microarray analysis (CMA), fluorescent
in situ hybridization (FISH), and cytogenetic analysis (karyotyping) for variants
of the SON gene can confirm the diagnosis.
Physical findings: How individuals are affected by ZTTK syndrome will vary based on where changes occurred
on the SON gene. Some common signs and symptoms of this condition may include:
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Unique facial features (facial asymmetry, midface retraction, deep-set eyes, low set
ears);
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Muscle abnormalities (low muscle tone, contractures or loose joints);
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Spinal curvature (scoliosis, kyphosis);
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Eye abnormalities (misaligned eyes, vision loss); and
ICD-9: 759.0
ICD-10: Q87.8
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PROGRESSION
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ZTTK syndrome typically progresses with a noticeable developmental delay, where intellectual
disability increases with age, often presenting with delayed motor skills, language
acquisition, and cognitive development, alongside potential brain abnormalities like
abnormal gyral patterns and white matter issues. Symptoms of ZTTK syndrome may start
to appear as a newborn. However, some symptoms can begin at any age. Seizures may
also develop between the ages of 1 and 6 years old in many patients, while other symptoms
like facial dysmorphisms and musculoskeletal abnormalities may become more apparent
over time.
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TREATMENT
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There is no cure for ZTTK syndrome. Treatment is supportive and based on individual
symptoms. A specialist care team may include genetics/genetic counseling, neurology,
psychiatry, cardiology, nephrology, ophthalmology, audiology, immunology, orthopedics,
and gastroenterology. Affected children should have imaging to screen for kidney and
heart abnormalities. Imaging of the brain may include MRI to identify structural brain
differences and EEG if seizures are suspected. Growth, feeding and development should
be monitored.
Supportive therapies such as speech, occupational, and physical therapies may be helpful,
and school aged children may benefit from accommodations such as an individualized
education plan (IEP). Genetic counseling is recommended for affected children and
their families.
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SUGGESTED PROGRAMMATIC ASSESSMENT*
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Suggested MER for Evaluation:
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Clinical history and examination that describes the diagnostic features of the impairment;
and
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Genetic testing confirming the presence of SON gene mutations.
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Suggested Listings for Evaluation:
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DETERMINATION
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LISTINGS
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REMARKS
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Meets
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101.18
101.24
102.02
102.03
102.04
102.10
104.06
110.08 B
111.02 A or B
111.09
112.02
112.05
112.11
112.14
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Equals
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* Adjudicators may, at their discretion, use the Medical Evidence of Record or the
listings suggested to evaluate the claim. However, the decision to allow or deny the
claim rests with the adjudicator.
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