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Test ID LBOR0220 Sex-Determining Region Y, Yp11.3 Deletion, FISH and Chromosome Analysis, Congenital

Important Note

Note:  Send completed Sanford Medical Genetics Requisition along with specimen. 

For non-Medicare patients, a separate completed and signed Commercial Insurance Patient Waiver of Liability is required to accompany the specimen.

or patients with Blue Cross Blue Shield of North Dakota Coverage, a separate completed and signed Advance Member Notice is required to accompany the specimen.  

AKA

SRY, Yp11.3, FISH

Specimen Type/Requirements

Dark Green top (Sodium Heparin w/out gel) - Whole Blood

 

Invert several times to mix blood.  Send whole blood specimen in original tube.

Do not aliquot.

 

Specimen Volume

 Preferred Volume     4 mL   
 Minimum Volume     2 mL   

 

Stability/Transport

 Room Temperature     48 - 72 hours     Preferred for transport   
 Refrigerated     48 - 72 hours     
 Frozen     Not Acceptable     

Note:  Samples received after 24 hours may result in compromised specimen integrity.

All specimens will be evaluated at the Sanford Medical Genetics Laboratory for test suitability.

Performed Test Frequency

Monday - Friday

Report Available

7 - 10 days

Additional Information

METHODS:
FISH
Fluorescence in situ hybridization (FISH) analysis was performed using a commercially available probe set, consisting of two probes on the Y chromosome, SRY located at Yq11.31 and DYZ1 located at the hetecrochromatic block at Yq12, as well as the chromosome X centromere probe DXZ1.  Metaphase cells are inspected for the presence of SRY.
Scoring Method: Manual

Chromosome Analysis
Whole blood is cultured with an additive to stimulate cell division. The cells are incubated for 48 hours at 37° Celsius. Cell cultures are synchronized with excess thymidine, arrested in metaphase with Colcemid, harvested, and fixed with methanol and acetic acid. Giemsa stain and trypsin are used to generate a characteristic banding pattern (G-banding) which permits unambiguous identification of individual chromosomes. (Arsham et al., The AGT Cytogenetics Laboratory Manual, Fourth Edition)

Metaphases with an average band-level resolution of 400-700 are routinely examined. Additional metaphases are analyzed in cases of suspected mosaicism. Two or more digital karyograms are prepared and stored using a computer-based imaging system. Chromosome abnormalities are confirmed in at least 2 different cultures. A minimum of 3 metaphases with the same chromosome loss, and a minimum of 2 metaphases with the same chromosome gain or structural abnormality are required to authenticate findings. (ACMG, Technical Standards for Clinical Genetics Laboratories (2021 Revision))

 

LIMITATIONS:
FISH
FISH assays are limited to the region(s) specific to the probe(s) being used.  A normal result does not rule out alterations elsewhere in the genome, small deletions or duplications within the sequence complementary to the probe, or point mutations. Metaphase FISH is not a reliable method for the detection of microduplications. This test’s sensitivity for detecting mosaicism is unknown.

Chromosome Analysis
Chromosomes at the 400-700 band-level of resolution generally have a detection limit of 5-10 megabases in regions where the banding pattern is distinctive. The detection limit may be adversely affected in regions lacking contrasting bands. Smaller genomic abnormalities may not be detected via G-banded chromosome studies (cryptic abnormalities). Some chromosomal anomalies hinder cell growth and may be selected against during routine cell culture processes resulting in underrepresentation or exclusion during final analysis. This test is not appropriate for detecting acquired chromosome abnormalities.

Methodology

Fluorescence in situ Hybridization

Performing Lab

Sanford Medical Genetics Laboratory - Sioux Falls

CPT

88271x2, 88230 AND 88291

and one of the following: 88272 or 88273 or 88274 or 88275

and one of the following: 88261 or 88262 or 88263

and where applicable 88271x1 up to x14

Useful For

For this test fluorescence in situ hybridization (FISH) analysis for the male sex-determining region of the Y chromosome, SRY, is ordered in conjunction with Chromosome Analysis. Chromosome analysis is preformed to rule out abnormalities, including translocations, involving the sex chromosomes or autosomes. While cryptic translocations or deletions involving the Sex Determining Region Y (SRY), not detectable by chromosome analysis, may be detected by FISH.


Sex Determining Region Y (SRY) FISH testing may be used to evaluate for the deletion or addition of SRY in individuals with a 46,XY karyotype and phenotypically normal female external genitalia or a 46,XX karyotype and phenotypically normal male external genitalia, clinical features of Nonsyndromic Disorders of Testicular Development and Nonsyndromic 46,XX Testicular Disorders/Differences of Sex Development, respectively.