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| Test Includes | This test covers all coding nucleotides of gene BBS1, plus at least two and typically 20 flanking intronic nucleotides upstream and downstream of each coding exon, covering the conserved donor and acceptor splice sites, as well as typically 20 flanking nucleotides in the 5′ and 3′ UTR. |
| Special Instructions | In cases in which a known mutation can be documented, the physician may prefer to order test252753.
Test orders must include an attestation that the provider has the patient’s informed consent for genetic testing. See sample physician office consent form: Consent for Genetic Testing. In the case of family tests (ie, known mutations), please submit the result report of the first patient tested in the family (the index case), if not performed at a LabCorp facility. Other family members are subsequently tested for the specific mutation found in the first patient tested. |
| Specimen | Whole blood; DNA is accepted (Call 800-345-4363 for DNA collection information.) |
| Volume | 2 mL |
| Container | Lavender-top (EDTA) tube |
| Collection | Samples may be stored for brief periods at 4°C. Ship overnight at room temperature. |
| Storage Instructions | Maintain specimen at room temperature. |
| Causes for Rejection | Container broken or leaking; container not labeled or label not legible; improper anticoagulant |
| Reference Interval | Normal equals reference sequence or variants that are known or predicted to be benign; abnormal equals all other variants. |
| Use | Confirm a clinical diagnosis of BBS; detect carriers; allow early diagnosis in family members |
| Limitations | This method does not reliably detect mosaic variants; large deletions; large duplications, inversions, or other rearrangements; or deep intronic variants. It may be affected by allele-dropout, it may not allow determination of the exact numbers of T/A or microsatellite repeats, and it does not allow any conclusion as to whether two heterozygous variants are present on the same or on different chromosome copies.
Results of this test are for investigational purposes only. The performance characteristics of this assay have been determined by LabCorp. The result should not be used as a diagnostic procedure without confirmation of the diagnosis by another medically established diagnostic product or procedure. |
| Methodology | DNA sequencing |
| Additional Information | Bardet-Biedl syndrome (BBS) is a recessively inherited disorder characterized by a range of manifestations, including retinal degeneration, postaxial polydactyly, obesity, anosmia, hypogonadism in males, complex genitourinary malformation in females, and renal abnormalities, which are a major cause of morbidity and early mortality. BBS has been associated with mutations in at least 12 genes. Among the known BBS genes, BBS1 is believed to account for about 23% of all cases. Genetic testing can confirm a clinical diagnosis of BBS and detect mutation carriers within affected families. |
| References | Beales PL, Elcioglu N, Woolf AS, et al. New criteria for improved diagnosis of Bardet-Biedl syndrome: Results of a population survey. J Med Genet. 1999; 36(6):437-446. PubMed 10874630
Katsanis N, Zaghloul NA. Mechanistic insights into Bardet-Biedl syndrome, a model ciliopathy. J Clin Invest. 2009; 119(3):428-437. PubMed 19252258 |
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