Carrier screening or diagnostic testing for Bloom syndrome for individuals of Ashkenazi Jewish descent.
- Patient Preparation
- Lavender (EDTA), pink (K2EDTA), or yellow (ACD Solution A or B).
- Specimen Preparation
- Transport 3 mL whole blood. (Min: 1 mL)
- Storage/Transport Temperature
- Unacceptable Conditions
- Plasma or serum. Specimens collected in sodium heparin or lithium heparin tubes.
- Ambient: 72 hours; Refrigerated: 2 weeks; Frozen: 1 month
Characteristics: Bloom syndrome is characterized by pre-and postnatal growth deficiency, sparse subcutaneous tissue, sun-sensitive telangiectatic hypo-and hyperpigmented skin lesions, chromosome instability causing benign and malignant tumors early in life, and male sterility.
Incidence: 1 in 40,000 in Ashkenazi Jewish individuals.
Inheritance: Autosomal recessive.
Cause: BLM pathogenic variants.
Variant Tested: p.Y736Lfs (c.2207_2212delinsTAGATTC).
Clinical Sensitivity: 97 percent in Ashkenazi Jewish individuals, approximately 3 percent in other ethnicities.
Methodology: Polymerase chain reaction (PCR) and fluorescence monitoring.
Analytical sensitivity and specificity: Greater than 99 percent.
Limitations: Variants other than c.2207_2212delinsTAGATTC will not be detected. Diagnostic errors can occur due to rare sequence variations.
|Component Test Code*||Component Chart Name||LOINC|
|0051435||Bloom Syndrome (BLM), Allele 1|
|0051436||Bloom Syndrome (BLM), Allele 2|
|0051437||Bloom Syndrome (BLM), Interpretation||46991-6|
|2001300||Bloom Syndrome (BLM), Specimen|
- BLM mutation testing