Molecular Genetics Platelet Disorders Panel

Inherited platelet disorders are a group of genetic conditions that cause excessive and uncontrollable bleeding. These life-threatening conditions cause complications following surgery, childbirth, trauma or internal hemorrhages. Pathogenic variants in genes encoding cytoskeletal proteins, platelet adhesions and signaling pathways triggering coagulation are analyzed in this next-generation sequencing-based panel test. The test also includes genes associated with Bernard-Soulier syndrome, Scott syndrome, Glanzmann’s thrombasthenia, Thromboxane A2 receptor deficiency, GP6 collagen receptor deficiency, and Hermansky-Pudlak syndrome. The mode of inheritance for platelet disorders is autosomal recessive or autosomal dominant. The overall incidence for inherited platelet disorders is estimated to be ~1:10,000. 

Reasons for Referral:

• Abnormal bleeding or bruising
• Uncontrollable bleeding
• Positive family history for bleeding disorders (targeted testing is available if familial mutation is known.)
• Carrier testing.

Next generation sequencing will analyze the exons or coding regions of 71 associated genes with platelet disorders using Illumina NextSeq 500/550 technology. Samples are prepared using hybridization probes to enrich exonic regions.  This assay does not assess regions of insufficient coverage, introns and promoter regions; pseudogenes; where the reference genome is inaccurate or contains gaps and insertions; and regions of high GC or polynucleotide repeats, but may contain variants that impact gene function.

Exon-level deletion/duplication analysis is performed by running the NGS data through the Genome Analysis Toolkit (GATK) Germline Copy Number Variation best practices pipeline from GATK, version 4.1.4.1. A Bayesian model was validated clinically in our lab. The model can detect copy changes at a resolution of three (3) or more probe targets (exons) for deletions and duplications in genes that do not have pseudogenes, and is not designed to detect low-level mosaicism or balanced alterations.

Coding region coverage for the Platelet Disorders panel genes

Coding regions below 95% may be covered upon request if further assessment of a gene is necessary (some exceptions may apply). Please contact Knight Diagnostic Laboratories for more information.

*VWF Exon 26 (NM_000552.3), a region with high homology is assessed via long-range PCR & Sanger sequencing

Blood:  EDTA or ACD (Solution A or B):

• Adult: 5 mL
• Child: 5 mL
• Infant: 2-3 mL

Saliva: 2 ORAgene™ Saliva Collection Kits (OGR-500) used according to manufacturer instructions.  Please contact KDL Client Services for a Saliva Collection Kit for patients that cannot provide a blood sample.

Assisted Saliva: 4 ORAgene™ Assisted Saliva Collection Kits (OGR-575) used according to manufacturer instructions.  Please contact KDL Client Services for an Assisted Saliva Collection Kit for patients that cannot provide a blood sample.

Skin Fibroblast: Punch Biopsy (Cell cultures will be prepared at KDL and used for testing), or 2 T-25 confluent flasks.

DNA: 5-10µg at a minimum of 60-100ng/µL (DNA must be extracted in a CLIA-certified laboratory or a laboratory meeting equivalent requirements as determined by the CAP and/or CMS).

Prenatal:

• Direct Amniotic Fluid (10-20mL)
• Direct CVS
• Direct POC
• Cultured Amniocytes (2 T-25 flasks)
• Cultured CVS (2 T-25 flasks)
• Cultured Fetal Tissue: Product of Conception (2 T-25 flasks)
• Cord Blood (1-2mL)

Notice Regarding Molecular Genetic Testing Prenatal Specimens:

Weekly

6-8 weeks

• Package and ship specimen to remain cold, but not frozen. 
• Ship via overnight express, using the FedEx priority overnight label provided. 
• Contact Client Services for shipping kits and instructions at (855) 535-1522.

1. Am J Hematol. 2010 Mar, 85(3):175-180
2. Hematology Am Soc Hematol Educ Program. 2011;2011:377-383
3. Hematology Am Soc Hematol Educ Program. 2005:396-402