Mayo Test Catalog, (Sorted By Test Name) - Mayo Medical ...

SMA
6284
Deletion/Duplication, FISH
Clinical Information: Smith-Magenis syndrome is associated with a deletion of the proximal short
arm of chromosome 17, including the critical RAI1 gene region. Although the phenotype is variable, the
syndrome can be suspected in patients with failure to thrive, brachycephaly (short head), prominent
forehead, microcephaly (small head), flat and broad midface, broad nasal bridge, strabismus, myopia,
malformed ears, high and cleft palate, prognathism (protruding mandible), short and broad hands and feet,
scoliosis (laterally curved spine), and cryptorchidism (undescended testes). Unusual features of the
syndrome include specific self-destructive behavior, including insertion of foreign objects into bodily
orifices, pulling out fingernails and toenails, and sleep abnormalities (especially disturbed rapid eye
movement sleep). Mental retardation is variable but usually severe with seizures and hyperactivity.
Patients with duplications of this region (Potocki-Lupski syndrome) tend to have a milder but overlapping
phenotype. FISH studies are highly specific and do not exclude other chromosome abnormalities. For this
reason, we recommend that patients suspected of having Smith-Magenis or Potocki-Lupski syndromes
also have conventional chromosome studies (CMS/8696 Chromosome Analysis, for Congenital
Disorders, Blood) performed to rule out other chromosome abnormalities or translocations.
Useful For: Aids in the diagnosis of 17p11.2 deletion (Smith-Magenis) and 17p11.2 duplication
(Potocki-Lupski) syndromes, in conjunction with CMS/8696 Chromosome Analysis, for Congenital
Disorders, Blood Detecting cryptic translocations involving 17p11.2, including the RAI1 critical region,
that are not demonstrated by conventional chromosome studies
Interpretation: Any individual with a normal signal pattern (2 signals for RAI1) in each metaphase is
considered negative for a deletion or duplication in the region tested by this probe. Any patient with a
FISH signal pattern indicating loss of the RAI1 critical region will be reported as having a deletion of the
regions tested by this probe. This is consistent with a diagnosis of 17p11.2 deletion (Smith-Magenis)
syndrome. Any patient with a FISH signal pattern indicating additional critical region signals will be
reported as having a duplication of the regions tested by this probe. This is consistent with a diagnosis of
17p11.2 duplication (Potocki-Lupski) syndrome.
Reference Values:
An interpretive report will be provided.
Clinical References: 1. Van Dyke DL, Wiktor A: Clinical cytogenetics. In Laboratory Medicine.
2nd edition. Edited by K McClatchey. Baltimore, Williams & Wilkins, 2002, Chapter 26 2. Juyal RC,
Greenberg F, Mengden GA, et al: Smith-Magenis syndrome deletion: a case with equivocal cytogenetic
findings resolved by fluorescence in situ hybridization. Am J Med Genet 1995;58:286-291 3. Potocki L,
Chen KS, Park SS, et al: Molecular mechanism for duplication 17p11.2-the homologous recombination
reciprocal of the Smith-Magenis microdeletion. Nat Genet 2000;24:84-87 4. Vlangos CN, Wilson M,
Blancato J, et al: Diagnostic FISH probes for del(17)(p11.2p11.2) associated with Smith-Magenis
syndromes should contain the RAI1 gene. Am J Med Genet 2005;132A:278-282 5. Elsea SH, Girirajan S:
Smith-Magenis Syndrome. Eur J Hum Genet 2008;16:412-421
Smooth Muscle Antibodies, Serum
Clinical Information: Sera from patients with autoimmune chronic active hepatitis contain antibodies
to smooth muscle antigens that are detectable by indirect immunofluorescence on substrates that contain
smooth muscle. The antibodies are predominantly of the IgG isotype. Other diseases in this differential
diagnosis group include primary biliary cirrhosis, chronic viral hepatitis, and alcoholic chronic hepatitis.
Useful For: Evaluating patients with chronic liver disease in whom the diagnosis of chronic active
autoimmune hepatitis is suspected
Interpretation: Antibody titers in the range of 80 to 320 occur commonly in patients with active
chronic hepatitis; lower titers (usually