Diamond-Blackfan Anemia
Diamond-Blackfan Anemia (DBA) is an inherited bone marrow
failure syndrome with hematological abnormalities typically presenting in the first year of life.
PrintDiamond-Blackfan Anemia (DBA) is an inherited bone marrow
failure syndrome with hematological abnormalities typically presenting in the first year of life.
Congenital anomalies affect 35-50% of patients and include craniofacial abnormalities, hypoplastic or malformed thumbs, and anomalies of the heart and genitourinary system. Patients are predisposed to malignancies including acute leukemias and sarcomas.
Up to 45% of cases are familial with autosomal dominant inheritance. Due to the wide clinical variability, disease state may not be obvious and at-risk family members should be evaluated for non-classical DBA. Mutations are detectable in approximately 53% of patients with Diamond-Blackfan Anemia by sequencing nine genes.
The Ambry SEQUENCE: Diamond-Blackfan Anemia is a testing pathway for Gene Sequence Analysis of nine genes which are known to cause DBA. Testing is arranged into three steps for maximum yield and minimum cost. For patients who have had previous RPS19 testing, Ambry SEQUENCE™: DBA may be started at Step 2 or tests may be ordered individually by gene.
Diamond-Blackfan Anemia (DBA) is an inherited bone marrow failure syndrome affecting approximately 1/150,000 children. The primary feature is red cell aplasia with normochromic macrocytic anemia and absent or insufficient erythroid precursors, typically presenting in the first year of life. Congenital anomalies affect 35-50% of patients and include craniofacial abnormalities, hypoplastic or malformed thumbs, and anomalies of the heart and genitourinary system. Common laboratory findings are increased mean corpuscular volume (MCV), elevated erythrocyte adenosine deaminase activity (eADA) and increased hemoglobin F. DBA is treated with steroids, transfusions, and hematopoietic stem cell transplantation. Patients are predisposed to malignancies including acute leukemias and sarcomas.1,2,3
Mutations are detectable in approximately 53% of patients with DBA by sequencing the nine genes demonstrated so far to harbor disease-causing mutations. All the genes encode proteins of the ribosome, which is itself the complex cellular structure that assembles proteins from amino acids. Testing for two additional genes that encode ribosomal proteins, RPL19 and RPL26, is also available. The genes and the approximate proportion of DBA cases attributable to mutations in these genes follow:
| Gene | Percentage | Description |
| RPS19 | 25%2 | Approximately 10% of RPS19 mutation-carrying patients, or 2-3% of all patients with DBA, have chromosomal rearrangements or large gene deletions which are not detectable by sequencing alone.4 Patients with RPS19 mutations are less sensitive to steroids and more likely to become transfusion-dependent or require stem cell transplant than other patients with DBA.2 |
| RPL5 | 7% | Mutations in this gene are associated with thumb, heart and craniofacial anomalies including cleft lip and palate.3,5 |
| RPL11 | 5% | Mutations in this gene are associated with thumb and heart anomalies.3,5 |
| RPL35A | 3%3 | |
| RPS26 | 6%9 | |
| RPS24 | 2%7 | |
| RPS17 | 1%8 | |
| RPS7 | 1%3 | |
| RPS10 | 3%9 | |
| RPL19 | unknown | |
| RPL26 | unknown |
Up to 45% of cases are familial with autosomal dominant inheritance. Due to the wide clinical variability, disease state may not be obvious and at-risk family members should be evaluated for non-classical DBA.
Genetic testing for Diamond-Blackfan Anemia is useful for diagnostic confirmation in patients with a known or suspected clinical diagnosis of DBA, for determining appropriate surveillance for at-risk relatives, and for prenatal diagnosis.
The Ambry SEQUENCE: Diamond-Blackfan Anemia is a testing pathway to sequentially analyze up to seven genes causing DBA. Testing can be performed concurrently, or it can be performed in three steps for maximum yield and minimum cost. Step 1 is sequence analysis of RPS19, if negative reflex to Step 2 which is concurrent sequence analysis of RPL5, RPL11, RPL35A and RPS26, if negative reflex to Step 3 which is concurrent sequence analysis of RPS24, RPS7, RPS17, RPS10.
For patients who have had previous RPS19 testing, the SEQUENCE may be started at Step 2 or tests may be ordered individually by gene. Specific mutation analysis for familial mutations in any gene is also available. Each test in the SEQUENCE is a gene sequence analysis performed by PCR-based double-stranded automated sequencing for the regions specified plus at least 20 bases into the 5’ and 3’ ends of all the introns. RPS19: 5’UTR and exons 2-6. RPL5: exons 1-8. RPL11: exons 1-6. RPL35A: exons 2-5. RPS26; exons 1-4. RPS24: exons 1-6. RPS17: exons 1-5. RPS7: exons 2-7. RPS10: exons 2-6 All are sequenced bidirectionally with the exception of the 3’ portion of RPL5 exon 7, which is sequenced in the sense direction only.
Gene sequence analysis of the RPL19 and RPL26 genes may be ordered separately. RPL26 exons 2-4, RPL19 exons 1-6 and at least 20 bp into the 5’ and 3’ ends of all the intronic regions are analyzed with the exception of RPL26 exon 4 which has no -20bp read.
| SEQUENCE Steps | Description | Detection Rate | TAT in days |
| Complete | Step 1, if negative then Step 2, if negative then Step 3 | ~45% | 21-42 |
| 1 | Gene sequence analysis of RPS19 | ~25% | 10-21 |
| 2 | Concurrent sequence analysis of RPL5, RPL11, RPL35A, RPS26 |
RPL5: ~7% |
14-28 |
| 3 | Concurrent sequence analysis of RPS24, RPS7, RPS17, RPS10 | RPS24: ~2% RPS17: ~1% RPS7: ~1% RPS10: ~3% |
14-28 |
Ambry SEQUENCE: Diamond-Blackfan Anemia identifies mutations in approximately 53% of DBA patients (clinical sensitivity). Chromosome rearrangements and large deletions of the RPS19 gene, which account for 2-3% of all DBA and about 10% of RPS19-related DBA, are not detected. Approximately 99% of described mutations in the analyzed regions are detectable for six of the seven genes; for RPS19 the analytic sensitivity is approximately 90%. DBA causing mutations have not been described in RPL26 and RPL19 genes to date.
Blood: Collect 3-5 cc from adult or 2 cc minimum from child into EDTA purple-top tube (first choice) or ACD yellow-top tube (second choice). Store at room temperature or refrigerate. Ship at room temperature.
Blood Spot: Call for availability.
Saliva: Collect 2 ml into Oragene™ DNA Self-Collection container. Store and ship at room temperature.
DNA: Minimum DNA Amount of 5μg of DNA at a concentration of ~100ng/μl in 50μl TE (10mM Tris-Cl pH 8.0, 1mM EDTA); preferred 20μg. Store frozen and ship on ice or dry ice.
Prenatal: Prenatal testing is available. Please call an Ambry Genetic Counselor to discuss your case.
| Test Code | Technique |
|---|---|
| 2560 | RPS19 Related DBA (Step 1) |
| 8542 | DBA Step1 Only |
| 2460 | RPL5 Related DBA (Step 2) |
| 2480 | RPL11 Related DBA (Step 2) |
| 2500 | RPL35A Related DBA (Step 2) |
| 2588 | RPS26 Related DBA (Step 2) |
| 8544 | DBA Step 2 Only RPL5, RPL11, RPL35A, RPS26 |
| 2520 | RPS7 Related DBA (Step 3) |
| 2540 | RPS17 Related DBA (Step 3) |
| 2580 | RPS24 Related DBA (Step 3) |
| 2584 | RPS10 Related DBA (Step 3) |
| 8545 | DBA Step 1 and 2 Only RPS19, RPL5, RPL11, RPL35A, RPS26 |
| 8547 | DBA Step 2 and 3 Only RPL5, RPL11, RPL35A, RPS24, RPS17, RPS7, RPS26, RPS10 |
| 8540 | DBA Reflex Option All Genes, Steps 1 - 3 |
| 8548 | DBA All Genes, Steps 1 - 3 |
| 5080 | RPL19 Related DBA |
| 5100 | RP2L6 Related DBA |
| Technique | Days |
|---|---|
| RPS19 Related DBA (Step 1) | 7-14 |
| DBA Step1 Only | 7-14 |
| RPL5 Related DBA (Step 2) | 7-14 |
| RPL11 Related DBA (Step 2) | 7-14 |
| RPL35A Related DBA (Step 2) | 7-14 |
| RPS26 Related DBA (Step 2) | 7-14 |
| DBA Step 2 Only RPL5, RPL11, RPL35A, RPS26 | 14-28 |
| RPS7 Related DBA (Step 3) | 7-14 |
| RPS17 Related DBA (Step 3) | 7-14 |
| RPS24 Related DBA (Step 3) | 7-14 |
| RPS10 Related DBA (Step 3) | 7-14 |
| DBA Step 1 and 2 Only RPS19, RPL5, RPL11, RPL35A, RPS26 | 14-28 |
| DBA Step 2 and 3 Only RPL5, RPL11, RPL35A, RPS24, RPS17, RPS7, RPS26, RPS10 | 14-28 |
| DBA Reflex Option All Genes, Steps 1 - 3 | 21-42 |
| DBA All Genes, Steps 1 - 3 | 14-28 |
| RPL19 Related DBA | 7-14 |
| RPL26 Related DBA | 7-14 |
1. Vlachos A et al. Diagnosing and treating Diamond Blackfan anaemia: results of an international clinical consensus conference. Br J Haematol. 2008;142(6):859-876. [PMID: 18671700]
2. Campagnoli MF et al. RPS19 mutations in patients with Diamond-Blackfan anemia. Hum Mutat. 2008;29(7):911-920. [PMID: 18412286]
3. Gazda HT et al. Ribosomal protein L5 and L11 mutations are associated with cleft palate and abnormal thumbs in Diamond-Blackfan anemia patients. Am J Hum Genet. 2008;83:769-780. [PMID: 19061985]
4. Quarello P et al. Multiplex ligation-dependent probe amplification enhances molecular diagnosis of Diamond-Blackfan anemia due to RPS19 deficiency. Haematologica. 2008;93(11):1748-1750. [PMID: 18835835]
5. Cmejla R et al. Identification of mutations in the ribosomal protein L5 (RPL5) and ribosomal protein L11 (RPL11) genes in Czech patients with Diamond-Blackfan anemia. Hum Mutat. 2009:30:321-327. [PMID: 19191325]
6. Farrar JE et al. Abnormalities of the large ribosomal subunit protein, Rpl35a, in Diamond-Blackfan anemia. Blood. 2008;112(5):1582-1591. [PMID: 18535205]
7. Gazda HT et al. Ribosomal protein S24 gene is mutated in Diamond-Blackfan anemia. Am J Hum Genet. 2006;79:1110-1118. [PMID: 17186470]
8. Cmejla R et al. Ribosomal protein S17 gene (RPS17) is mutated in Diamond-Blackfan anemia. Hum Mutat. 2007;28(12):1178-1182. [PMID: 17647292]
9. Doherty L et al. Ribosomal protein genes RPS10 and RPS26 are commonly mutated in Diamond-Blackfan anemia. Am J Hum Genet. 2010;86:222–228. [PMID: 20116044]