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Alpha thalassaemia-mental retardation, X linked
1MRC Molecular Haematology Unit, Weatherall Institute of Molecular Medicine, John Radcliffe Hospital, University of Oxford, Headington, OX3 9DS Oxford, UK. richard.gibbons@imm.ox.ac.uk
Orphanet Journal of Rare Diseases
|May 26, 2006
Summary
X-linked alpha thalassaemia mental retardation (ATR-X) syndrome causes developmental delay and physical abnormalities in males due to ATRX gene mutations. Diagnosis involves genetic and protein studies, with multidisciplinary management crucial for affected individuals.
Area of Science:
- Genetics
- Pediatrics
- Neurology
Background:
- X-linked alpha thalassaemia mental retardation (ATR-X) syndrome affects males, presenting with severe developmental delay, distinctive facial features, genital abnormalities, and alpha thalassaemia.
- Female carriers are typically asymptomatic, while affected males exhibit limited language, seizures in about one-third of cases, and variable social behaviors, including autistic-like traits.
- Genital abnormalities are prevalent, occurring in 80% of affected children, ranging from undescended testes to ambiguous genitalia.
Purpose of the Study:
- To summarize the clinical presentation, genetic basis, diagnostic approaches, and management strategies for ATR-X syndrome.
- To highlight the role of ATRX gene mutations in the syndrome's pathophysiology and clinical phenotype.
- To provide an overview of the current understanding of ATR-X syndrome for healthcare professionals and families.
Main Methods:
- Review of reported cases and existing literature on ATR-X syndrome.
- Analysis of clinical features, including developmental delay, facial dysmorphism, genital abnormalities, and associated conditions like alpha thalassaemia and seizures.
- Genetic and molecular studies, including ATRX gene mutation detection, ATRX protein analysis, and X-inactivation studies.
Main Results:
- ATR-X syndrome is caused by mutations in the ATRX gene, encoding the ATRX protein, which influences DNA methylation patterns.
- Clinical manifestations are diverse, with profound developmental delay, hypotonia, characteristic facial features, and significant genital abnormalities being common.
- Alpha thalassaemia is not a universal feature, and the precise link between ATRX mutations, DNA methylation changes, and the clinical phenotype remains under investigation.
Conclusions:
- Diagnosis of ATR-X syndrome can be confirmed through a combination of clinical findings, alpha thalassaemia screening, and molecular genetic testing of the ATRX gene.
- Multidisciplinary management is essential, with careful monitoring for complications such as gastro-oesophageal reflux, which can be life-threatening in young children.
- Genetic counseling is recommended for families, and while the syndrome causes significant challenges, some individuals can live into their 30s and 40s.
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