The Invitae Barth Syndrome Test analyzes the TAZ gene. Pathogenic variants in this gene cause Barth syndrome, an inborn error of lipid metabolism. Genetic testing of this gene may confirm a diagnosis and help guide treatment and management decisions. Identification of a disease-causing variant would also guide testing and diagnosis of at-risk relatives.
The Invitae Organic Acidemias Panel and the Invitae Elevated C5-OH Panel have been designed to provide a broad genetic analysis of this class of disorders. Depending on the individual’s clinical and family history, one of these broader panels may be appropriate. They can be ordered at no additional cost.
Barth syndrome, also known as 3-methylglutaconic aciduria type II, is characterized by cardiomyopathy, neutropenia, skeletal myopathy, growth and/or developmental delay, and distinct facial features in affected males. Cardiomyopathy in males can present as dilated cardiomyopathy (DCM) or left ventricular noncompaction (LVNC), or in some cases as hypertrophic cardiomyopathy (HCM). Carrier females may present with cardiomyopathy—typically DCM without the other features of Barth syndrome—or may remain asymptomatic.
The TAZ gene encodes Tafazzin, an enzyme required for cardiolipin remodelling that maintains the function of mitochondria. Mitochondrial abnormalities in Barth syndrome compromise the development and function of tissues with high energy demand (e.g., heart and skeletal muscles). Biochemically, patients typically present 3-methylglutaconic aciduria, which may be a result of mitochondrial leakage of metabolites from leucine degradation and hypocholesterolaemia; however, disease expressivity and age of onset vary considerably.
TAZ is the only gene whose pathogenic variants are known to cause Barth syndrome.
Barth syndrome is an X-linked genetic condition (a pathogenic variant can be transmitted from mother to son), though the occurrence of de novo pathogenic variants may be relatively high.
The estimated incidence of Barth syndrome is 1 in 300,000–400,000 live births in the US, 1.5 in 1,000,000 live births in France, and 1 in 140,000 live births in England.
Testing for Barth syndrome should be considered for male infants or children with dilated idiopathic cardiomyopathy, neutropenia, 3-methylglutaconic aciduria, abnormal mitochondria within cardiac muscle, and/or idiopathic myopathy association growth retardation.
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Invitae is a College of American Pathologists (CAP)-accredited and Clinical Laboratory Improvement Amendments (CLIA)-certified clinical diagnostic laboratory performing full-gene sequencing and deletion/duplication analysis using next-generation sequencing technology (NGS).
Our sequence analysis covers clinically important regions of each gene, including coding exons, +/- 10 base pairs of adjacent intronic sequence, and select noncoding variants. Our assay provides a Q30 quality-adjusted mean coverage depth of 350x (50x minimum, or supplemented with additional analysis). Variants classified as pathogenic or likely pathogenic are confirmed with orthogonal methods, except individual variants that have high quality scores and previously validated in at least ten unrelated samples.
Our analysis detects most intragenic deletions and duplications at single exon resolution. However, in rare situations, single-exon copy number events may not be analyzed due to inherent sequence properties or isolated reduction in data quality. If you are requesting the detection of a specific single-exon copy number variation, please contact Client Services before placing your order.
|Gene||Transcript reference||Sequencing analysis||Deletion/Duplication analysis|