TAR syndrome is inherited in an autosomal recessive manner and is due to changes in the gene RBM8A (1q21.1). Compound inheritance of one RBM8A null allele and one RBM8A partial loss-of-function allele cause TAR syndrome. For the majority of individuals with TAR syndrome, the null allele is a total RBM8A gene deletion, as part of a recurring deletion of chromosome 1q21.1 that removes RBM8A as well as several other genes. Two partial loss-of-function RBM8A alleles have been described: a c.-21G>A nucleotide change in the 5’UTR and a c.67+32G>C nucleotide change in the first intron. These two nucleotide changes lower RBM8A transcription in vitro.
TAR clinical testing requires a comprehensive strategy to detect large deletions and RBM8A sequence variants. The 1q21.1 TAR deletion is mediated by segmental duplications and varies in size from ~200 kilobases (kb) to more than 2 Megabases (Mb); thus, high-resolution array Comparative Genome Hybridization (aCGH) is the most appropriate method to detect 1q21.1 deletions. RBM8A sequence variants are best detected with Sanger sequencing. The comprehensive TAR Syndrome Panel (Test Code: XM060) includes 1q21.1 deletion/duplication analysis by high-resolution aCGH and RBM8A full gene sequence analysis. Comprehensive TAR testing can provide confirmation of a clinical diagnosis and carrier testing for family members. The two components of the TAR panel may also be ordered as stand-alone tests (1q21.1 deletion/duplication, test code CC061, and RBM8A gene sequencing, test code MS061).
Please note that this test is for the RBM8A gene sequencing only.
- Confirmation of a clinical diagnosis of TAR syndrome
- Carrier testing in adults with a family history of TAR syndrome.
Analytical Sensitivity: ~99%
Submit only 1 of the following specimen types
Preferred specimen type: Whole Blood
Type: Whole Blood
Specimen Requirements:In EDTA (purple top) or ACD (yellow top) tube:
Infants (<2 years): 2-3 ml
Children (>2 years): 3-5 ml
Older Children & Adults: 5-10 ml
Specimen Collection and Shipping: Refrigerate until time of shipment. Ship sample within 5 days of collection at room temperature with overnight delivery.
Specimen Requirements:OrageneTM Saliva Collection kit (available through EGL) used according to manufacturer instructions.
Specimen Collection and Shipping: Store sample at room temperature. Ship sample within 5 days of collection at room temperature with overnight delivery.
- Custom diagnostic mutation analysis (KM) is available to family members for mutations identified by sequencing.
- Deletion testing is available to test for whole RBM8A gene deletions, as part of recurring TAR deletions on chromosome 1q21.1 that range from ~200 kb to 2 Mb (Test Code: CC061).
- TAR Panel - includes RBM8A sequencing and 1q21.1 deletion/duplication testing (Test Code: XM060).