Sorted By Test Name - Mayo Medical Laboratories

LY27B
9648
HMBSS
61216
histocompatibility gene cluster and is inherited tightly linked to the HLA-B*5701 allele. See Abacavir
Hypersensitivity Testing and Initial Patient Management Algorithm in Special Instructions.
Useful For: Predicting likelihood of hypersensitivity reactions to abacavir in HIV-infected patients,
based on the presence of the HLA-B*5701 allele Excluding HIV-infected patients from receiving abacavir
therapy Aiding in differentiating between true hypersensitivity to abacavir versus other underlying causes
(eg, concomitant infection, reaction to other drugs, or inflammatory disease)
Interpretation: Positivity for HLA-B*5701 confers high risk for hypersensitivity to abacavir. See
Abacavir Hypersensitivity Testing and Initial Patient Management Algorithm in Special Instructions.
Reference Values:
An interpretive report will be provided.
Clinical References: 1. Mallal S, Nolan D, C Witt, et al: Association between presence of
HLA-B*5701, HLA-DR7, and HLA-DQ3 and hypersensitivity to HIV-1 reverse-transcriptase inhibitor
abacavir. Lancet 2002;359:727-732 2. Faruki H, Heine U, Brown T, et al: HLA-B*5701 clinical testing:
early experience in the United States. Pharmacogenet Genom 2007;17:857-860 3. Sun HY, Hung CC, Lin
PH, et al: Incidence of abacavir hypersensitivity and its relationship with HLA-B*5701 in HIV-infected
patients in Taiwan. J. Antimicrob Chemother 2007;60:599-604 4. Mallal S, Phillips E, Carosi G, et al:
HLA-B*5701 screening for hypersensitivity to abacavir. N.Engl J Med 2008;358:568-579 5. Saag M,
Balu R, Brachman P, et al: High sensitivity of HLA-B*5701 in whites and blacks in
immunologically-confirmed cases of abacavir hypersensitivity. 4th IAS Conference on HIV Pathogenesis,
Treatment, and Prevention. July 22-25, 2007. Sydney. Abstract WEAB305)
HLA-B27, Blood
Clinical Information: This major histocompatibility coded class I antigen is associated with
ankylosing spondylitis, juvenile rheumatoid arthritis, and Reiterâ€s syndrome. The mechanism of the
association is not understood but probably is that of linkage disequilibrium. There is an increased
prevalence of HLA-B27 in certain rheumatic diseases, particularly ankylosing spondylitis.
Useful For: Assisting in the diagnostic process of ankylosing spondylitis, juvenile rheumatoid arthritis,
and Reiterâ€s syndrome
Interpretation: Approximately 8% of the normal population carries the HLA-B27 antigen. HLA-B27
is present in approximately 89% of patients with ankylosing spondylitis, 79% of patients with Reiter's
syndrome, and 42% of patients with juvenile rheumatoid arthritis. However, lacking other data, it is not
diagnostic for these disorders.
Reference Values:
An interpretive report will be provided.
Clinical References: 1. Brewerton DA, Hart FD, Nicholls A, et al: Ankylosing spondylitis and
HLA-27. Lancet 1973;1:904-907 2. Albrecht J, Muller HA: HLA-B27 typing by use of flow
cytofluorometry. Clin Chem 1987;33:1619-1623
HMBS Gene, Full Gene Analysis
Clinical Information: Hydroxymethylbilane synthase (HMBS) deficiency is an autosomal dominant
disorder with incomplete penetrance that can present as acute intermittent porphyria (AIP). The most
common clinical presentation of AIP is abdominal pain. Acute attacks can include vomiting, diarrhea,
constipation, urinary retention, acute episodes of neuropathic symptoms, psychiatric symptoms, seizures,
respiratory paralysis, tachycardia, and hypertension. Respiratory paralysis can progress to coma and
death. HMBS deficiency can also be without clinical or biochemical manifestations. Acute attacks may be
prevented by avoiding both endogenous and exogenous triggers. These triggers include porphyrogenic
drugs, hormonal contraceptives, fasting, alcohol, tobacco and cannabis. The measurement of
porphobilinogen deaminase (PBG-D) enzyme activity in erythrocytes facilitates detection of AIP during
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