Clinical characteristics: Tatton-Brown-Rahman syndrome (TBRS) is an overgrowth / intellectual disability syndrome characterized by length/height and/or head circumference ≥2 standard deviations above the mean for age and sex, obesity / increased weight, intellectual disability that ranges from mild to severe, joint hypermobility, hypotonia, behavioral/psychiatric issues, kyphoscoliosis, and seizures. Individuals with TBRS have subtle dysmorphic features, including a round face with coarse features, thick horizontal low-set eyebrows, narrow (as measured vertically) palpebral fissures, and prominent upper central incisors. The facial gestalt is most easily recognizable in the teenage years. TBRS may be associated with an increased risk of developing acute myeloid leukemia. There are less clear associations with aortic root dilatation and increased risk of other hematologic and solid tumors.
Diagnosis/testing: The diagnosis of TBRS is established in a proband with suggestive findings and a heterozygous pathogenic variant in DNMT3A identified by molecular genetic testing
Management: Treatment of manifestations: Treatments are primarily supportive and based on symptoms. Developmental delay / intellectual disability, behavioral/psychiatric diagnoses, epilepsy, joint hypermobility, kyphoscoliosis, sleep apnea, cryptorchidism, and acute leukemia are all treated in the standardized fashion.
Surveillance: Monitoring of growth parameters, developmental progress, behavior, mobility, and self-help skills at each visit. Assessment for new neurologic manifestations, seizures, and signs and symptoms of sleep apnea and hematologic malignancies at each visit. Low threshold for complete blood count with differential and further investigations in those who have concerning signs and symptoms of hematologic malignancy; there are no consensus guidelines regarding screening for hematologic malignancy in individuals with TBRS.
Genetic counseling: TBRS is an autosomal dominant disorder typically caused by a de novo pathogenic variant. Rarely, individuals diagnosed with TBRS have the disorder as the result of a DNMT3A pathogenic variant inherited from a parent. Each child of an individual with TBRS has a 50% chance of inheriting the DNMT3A pathogenic variant. Once the DNMT3A pathogenic variant has been identified in an affected family member, prenatal and preimplantation genetic testing are possible.
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