Sorted By Test Name - Mayo Medical Laboratories

WSCR
81163
Class IgE kU/L Interpretation
0 Negative
1 0.35-0.69 Equivocal
2 0.70-3.49 Positive
3 3.50-17.4 Positive
4 17.5-49.9 Strongly positive
5 50.0-99.9 Strongly positive
6 > or =100 Strongly positive Reference values
apply to all ages.
Clinical References: Homburger HA: Allergic diseases. In Clinical Diagnosis and Management by
Laboratory Methods. 21st edition. Edited by RA McPherson, MR Pincus. New York, WB Saunders
Company, 2007, Chapter 53, Part VI, pp 961-971
Williams Syndrome, 7q11.23 Deletion, FISH
Clinical Information: Williams syndrome (WS) is a genetic disorder that occurs in 1/20,000 to
1/50,000 live births. Although WS is typically a sporadic disorder, familial cases have been reported. WS
is characterized by a variable combination of cardiovascular abnormalities, connective tissue
abnormalities, distinct facial features, infantile hypercalcemia, mental retardation, and characteristic social
interactions such as extreme friendliness and attention-deficit hyperactivity disorder. Isolated congenital
narrowing of the ascending aorta is common in WS patients and results in a separate syndrome called
supravalvular aortic stenosis (SVAS). WS is a contiguous gene deletion syndrome, caused by deletion of
several genes on chromosome 7q. One gene that often is deleted in WS is the elastin gene, which causes
SVAS and other cardiovascular disease in these patients. This association was described by Ewart et al
(1993) who identified hemizygosity of the elastin gene in WS and SVAS. The elastin gene, ELN, has
been mapped to 7q11.23 (Williams syndrome chromosome region, and is reportedly hemizygous in up to
96% of patients with WS. The deletion of an elastin gene locus cannot be detected by conventional
high-resolution chromosome analysis in the vast majority of cases due to the small size of this deletion.
Nickerson et al used molecular methods to detect a deletion of the elastin gene in 91% (39/43) of WS
patients.
Useful For: Detecting deletions of the elastin gene at 7q11.23 Diagnosis of Williams syndrome, when
used in combination with high-resolution chromosome studies and clinical evaluation
Interpretation: An interpretive report is provided. The use of high-resolution chromosome studies and
FISH for Williams syndrome chromosome region should diagnose about 96% of Williams syndrome
patients and, at the same time, identify any other chromosome anomalies.
Reference Values:
An interpretive report will be provided.
Clinical References: 1. Ewart AK, Morris CA, Atkinson D, et al: Hemizygosity at the elastin locus
in a developmental disorder, Williams syndrome. Nature Genet 1993;5:11-16 2. Jalal SM, Crifasi PA,
Karnes PS, Michels VV: Cytogenetic testing for Williams syndrome. Mayo Clin Proc 1996;71:67-68 3.
Lowery MC, Morris CA, Ewart AK, et al: Strong correlation of elastin deletions, detected by FISH, with
Williams syndrome, evaluation of 235 patients. Am J Hum Genet 1995;57:49-53 4. Morris CA, Demsey
SA, Leonar CO, et al: Natural history of Williams syndrome. J Pediatr 1988;113:318-326 5. Olson TM,
Michels VV, Lindor NM, et al: Autosomal dominant aortic stenosis: localization to chromosome 7. Hum
Mol Genet 1993;2:869-873
WILL
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