ZTTK syndrome: Difference between revisions

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==Other Names==
{{Infobox medical condition
Zhu-Tokita-Takenouchi-Kim syndrome; Brain malformations-musculoskeletal abnormalities-facial dysmorphism-intellectual disability syndrome
| name = ZTTK Syndrome
| image = <!-- Image of the condition -->
| caption = <!-- Caption for the image -->
| field = [[Medical genetics]]
| symptoms = Developmental delay, intellectual disability, distinctive facial features
| onset = Congenital
| duration = Lifelong
| causes = Mutations in the [[SON gene]]
| risks = Genetic inheritance
| diagnosis = Genetic testing
| treatment = Symptomatic and supportive care
| prognosis = Variable
}}


==Pathophysiology==
'''ZTTK Syndrome''' is a rare [[genetic disorder]] characterized by a combination of developmental delay, intellectual disability, and distinctive facial features. It is caused by mutations in the [[SON gene]], which plays a crucial role in [[RNA splicing]] and [[gene expression]].
'''ZTTK Syndrome (Zhu-Tokita-Takenouchi-Kim syndrome)''' is a rare disease caused in humans by a genetic mutation of the [[SON (gene)|SON gene]].  


==Symptoms==
==Signs and Symptoms==
Common symptoms include moderate to severe [[intellectual disability]] and [[developmental delay]].
Individuals with ZTTK Syndrome typically present with a range of clinical features, including:
* [[Developmental delay]]
* [[Intellectual disability]]
* Distinctive [[facial features]] such as a broad forehead, flat nasal bridge, and downturned corners of the mouth
* [[Hypotonia]] (reduced muscle tone)
* [[Seizures]]
* [[Congenital heart defects]]
* [[Gastrointestinal issues]]
* [[Hearing loss]]


Characteristic abnormalities include cerebral cortex malformations, vision difficulties, [[Musculoskeletal abnormality|musculoskeletal abnormalities]] and [[Birth defect|congenital defects]]. Individuals with a mutation in the SON gene may not all display these features. However, SON loss of function (LoF) variants appear to cause a clinically distinguished phenotype.
==Genetics==
ZTTK Syndrome is caused by mutations in the [[SON gene]], located on chromosome 21. The SON gene is involved in the regulation of [[RNA splicing]], a process essential for the proper expression of many genes. Mutations in this gene disrupt normal cellular function, leading to the diverse symptoms observed in affected individuals.


== Signs and Symptoms ==
==Diagnosis==
The key signs and symptoms associated with ZTTK Syndrome patients include ocular, facial and systemic features.
Diagnosis of ZTTK Syndrome is primarily based on [[genetic testing]]. [[Whole exome sequencing]] or [[targeted gene panels]] can identify mutations in the SON gene. Clinical evaluation of symptoms and family history may also aid in diagnosis.


=== Ocular Features ===
==Management==
Distinctive ocular features of the ZTTK syndrome are deep-set eyes, down-slanting palpebral fissures and horizontal eyebrows.
There is currently no cure for ZTTK Syndrome. Management focuses on symptomatic and supportive care, which may include:
* [[Physical therapy]] to improve motor skills
* [[Speech therapy]] to address communication difficulties
* [[Occupational therapy]] to enhance daily living skills
* [[Anticonvulsant medications]] for seizure control
* Regular monitoring and treatment of [[cardiac]] and [[gastrointestinal]] issues


=== Facial Features ===
==Prognosis==
Individuals with ZTTK syndrome have distinctive minor to moderate facial dysmorphisms. Distinct facial features include facial asymmetry, low-set ears, midface retraction, frontal bossing, a depressed and or broad nasal bridge and a smooth or short philtrum.
The prognosis for individuals with ZTTK Syndrome varies depending on the severity of symptoms and the presence of associated health issues. Early intervention and supportive therapies can improve quality of life and developmental outcomes.


=== Systemic Features ===
==Epidemiology==
Multi-system abnormalities are common in ZTTK syndrome. The majority of individuals diagnosed with ZTTK syndrome display congenital malformations such as urogenital and malformations, heart defects, and a high or cleft palate.
ZTTK Syndrome is an extremely rare condition, with only a limited number of cases reported in the medical literature. It affects both males and females equally and is not restricted to any specific ethnic group.


Congenital defects such as a thinned atrial septum, [[ventricular septal defect]]s, [[patent ductus arteriosus]], dysplastic kidney and agenesis of the lung and gallbladder have also been noted.
==See Also==
* [[Genetic disorders]]
* [[Developmental delay]]
* [[Intellectual disability]]


=== Central Nervous System ===
==External Links==
Developmental delay is common in ZTTK syndrome patients, and appears to progressively increase the severity of intellectual disability with age.
* [Genetic and Rare Diseases Information Center]
* [National Organization for Rare Disorders]


=== Physiological ===
{{Medical conditions related to genetic disorders}}
Mutations of the SON gene can affect metabolism and mitochondrial function in newborns with ZTTK syndrome. Metabolic screening confirmed mitochondrial dysfunction and [[O-glycosylation]] defects in individuals with ZTTK syndrome. Decreased levels of immunoglobulin A and or immunoglobulin G identified in ZTTK syndrome patients resulted in coagulation abnormalities.
[[Category:Genetic disorders]]
 
[[Category:Rare diseases]]
== Genetics ==
[[Category:Developmental disorders]]
ZTTK syndrome is caused by heterozygous mutations in the SON gene.
As an [[autosomal dominant]] disease, children with parents carrying a SON mutation have a 50% risk of inheriting the mutation. However, the majority of affected individuals have de novo mutations in the SON gene and ZTTK syndrome is not inherited to their children.
 
== Diagnosis ==
 
=== Brain Imaging ===
Early diagnosis of the ZTTK syndrome can be determined by brain imaging. Magnetic resonance imaging (MRI) of the brain of ZTTK syndrome patients have revealed significant abnormalities.<ref name=":0" />
 
Abnormal gyration patterns were seen, including [[polymicrogyria]]; many unusually small folds in the brain, simplified gyria; reduced number and shallow appearance of gyri, and periventricular nodular heterotopia; failure of neurons to migrate properly during early development of the fetal brain.
 
[[Ventriculomegaly]] can also be observed in MRI where the [[lateral ventricles]] become dilated in the foetus and can contribute to developmental delays in ZTTK syndrome individual.
 
Other pathological features seen on MRI scans of ZTTK syndrome individuals include [[arachnoid cyst]]s, [[hypoplasia of the corpus callosum]] and cerebellar hemispheres and loss of periventricular white matter.<ref name=":0" />
 
Most individuals with ZTTK syndrome are identified early in childhood due to developmental delays and intellectual disabilities.<ref name=":11">{{Cite journal|last=Vissers|first=Lisenka E. L. M.|last2=Gilissen|first2=Christian|last3=Veltman|first3=Joris A.|date=2015-10-27|title=Genetic studies in intellectual disability and related disorders|journal=Nature Reviews Genetics|volume=17|issue=1|pages=9–18|doi=10.1038/nrg3999|pmid=26503795|issn=1471-0056}}</ref> However, a formal diagnosis of intellectual disability can only be conducted by a performance of an IQ test score of below 70.<ref name=":10" />
 
=== Whole Exome Sequencing ===
[[Whole exome sequencing]] (WES) can be used as a non-biased tool in the diagnostic evaluation of individuals with suspected genetic disorders such as the ZTTK syndrome.<ref name=":0" /> Using WES, individuals were identified with truncating variants of SON and overlapping clinical features.
 
ZTTK syndrome has been identified as a neurodevelopmental disorder associated with a de novo mutation in the SON gene using WES. The SON gene is known to be a major cause of severe intellectual disability and consequent developmental disorders.<ref name=":11" /> The first de novo truncating variant in SON was recognised in a group of individuals with severe intellectual disabilities.<ref name=":3" /> Sanger sequencing or the use of WES of parental samples confirmed the de novo status of the truncating and missense mutations of the SON gene in the sampled ZTTK syndrome individuals.<ref name=":0" /> Variants identified included a premature stop variant in exon 3, frame-shift variants in exon 3 and a frameshift variant in exon 4.<ref name=":0" />
 
== Treatment ==
There is currently no treatment for ZTTK syndrome. However, physical therapy and addressing the specific problems of multi organ disorders may be helpful.<ref name=":1" /> The main focus should be on the diagnosis and care of individuals with ZTTK syndrome.
 
[[Category:Rare syndromes]]
[[Category:Genetic syndromes]]
[[Category:Syndromes with mental retardation]]
{{adapted}}

Revision as of 12:37, 31 December 2024

ZTTK Syndrome
Synonyms N/A
Pronounce N/A
Specialty N/A
Symptoms Developmental delay, intellectual disability, distinctive facial features
Complications N/A
Onset Congenital
Duration Lifelong
Types N/A
Causes Mutations in the SON gene
Risks Genetic inheritance
Diagnosis Genetic testing
Differential diagnosis N/A
Prevention N/A
Treatment Symptomatic and supportive care
Medication N/A
Prognosis Variable
Frequency N/A
Deaths N/A


ZTTK Syndrome is a rare genetic disorder characterized by a combination of developmental delay, intellectual disability, and distinctive facial features. It is caused by mutations in the SON gene, which plays a crucial role in RNA splicing and gene expression.

Signs and Symptoms

Individuals with ZTTK Syndrome typically present with a range of clinical features, including:

Genetics

ZTTK Syndrome is caused by mutations in the SON gene, located on chromosome 21. The SON gene is involved in the regulation of RNA splicing, a process essential for the proper expression of many genes. Mutations in this gene disrupt normal cellular function, leading to the diverse symptoms observed in affected individuals.

Diagnosis

Diagnosis of ZTTK Syndrome is primarily based on genetic testing. Whole exome sequencing or targeted gene panels can identify mutations in the SON gene. Clinical evaluation of symptoms and family history may also aid in diagnosis.

Management

There is currently no cure for ZTTK Syndrome. Management focuses on symptomatic and supportive care, which may include:

Prognosis

The prognosis for individuals with ZTTK Syndrome varies depending on the severity of symptoms and the presence of associated health issues. Early intervention and supportive therapies can improve quality of life and developmental outcomes.

Epidemiology

ZTTK Syndrome is an extremely rare condition, with only a limited number of cases reported in the medical literature. It affects both males and females equally and is not restricted to any specific ethnic group.

See Also

External Links

  • [Genetic and Rare Diseases Information Center]
  • [National Organization for Rare Disorders]

Template:Medical conditions related to genetic disorders

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