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Is MED13L-related intellectual disability a recognizable syndrome?
Pernille Mathiesen Tørring1, Martin Jakob Larsen1, Charlotte Brasch-Andersen1
1Department of Clinical Genetics, Odense University Hospital, Odense, Denmark.
Introduction:
MED13L-related intellectual disability is characterized by moderate intellectual disability (ID), speech impairment, and dysmorphic facial features. We present 8 patients with MED13L-related intellectual disability and review the literature for phenotypical and genetic aspects of previously described patients.
Materials And Methods:
In the search for genetic aberrations in individuals with ID, two of the patients were identified by chromosomal microarray analysis, and five by exome sequencing. One of the individuals, suspected of MED13L-related intellectual disability, based on clinical features, was identified by Sanger sequencing.
Results:
All 8 individuals had de novo MED13L aberrations, including two intragenic microdeletions, two frameshift, three nonsense variants, and one missense variant. Phenotypically, they all had intellectual disability, speech and motor delay, and features of the mouth (open mouth appearance, macroglossia, and/or macrostomia). Two individuals were diagnosed with autism, and one had autistic features. One had complex congenital heart defect, and one had persistent foramen ovale. The literature was reviewed with respect to clinical and dysmorphic features, and genetic aberrations.
Conclusions:
Even if most clinical features of MED13L-related intellectual disability are rather non-specific, the syndrome may be suspected in some individuals based on the association of developmental delay, speech impairment, bulbous nasal tip, and macroglossia, macrostomia, or open mouth appearance.
Insights
MED13L-related intellectual disability (ID) presents with moderate ID, speech issues, and distinct facial features. This study details 8 new cases and reviews existing literature, identifying de novo MED13L aberrations in all patients.
Area of Science:
- Genetics
- Neurodevelopmental Disorders
- Human Disease
Background:
- MED13L-related intellectual disability (ID) is a genetic disorder.
- It is characterized by moderate ID, speech impairment, and dysmorphic facial features.
- This study investigates genetic aberrations and phenotypic aspects of MED13L-related ID.
Observation:
- Eight patients with MED13L-related ID were identified through chromosomal microarray, exome sequencing, and Sanger sequencing.
- All patients presented with de novo MED13L aberrations, including microdeletions, frameshift, nonsense, and missense variants.
- Common phenotypic features included intellectual disability, speech and motor delays, and specific oral features (open mouth, macroglossia, macrostomia).
Findings:
- Intellectual disability, speech and motor delays, and oral anomalies were consistent findings.
- Associated conditions included autism spectrum disorder (ASD) in two individuals and congenital heart defects in two others.
- Literature review confirmed a spectrum of clinical and dysmorphic features associated with MED13L aberrations.
Implications:
- MED13L-related ID may be suspected in individuals with developmental delay, speech impairment, and specific facial features like a bulbous nasal tip and oral anomalies.
- Accurate genetic diagnosis is crucial for understanding the phenotype and providing appropriate management.
- Further research can elucidate genotype-phenotype correlations and improve diagnostic criteria for MED13L-related disorders.
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