Test Directory

• SRY, Yp11.31
• DYZ1, Yq12
• Xcen, DXZ1, Xp11.1-q11.1

Fluorescence in situ hybridization (FISH) with the SRY (sex reversal Y) probe detects deletion in Yp11.3, that may be related to gonadal dysgenesis or sex reversal.

Males typically have one X chromosome and one Y chromosome in each diploid cell of their bodies. Females typically have two X chromosomes. XX males that are SRY-positive have two X chromosomes, with one of them containing genetic material (the SRY gene) from the Y chromosome; this gene causes them to develop a male phenotype despite having chromosomes more typical of females. Some XX males, however, do not have the SRY gene (SRY-negative) and the male phenotype may be caused by another gene on one of the autosomes. The SRY gene, normally found on the Y chromosome, plays an important role in sex determination by initiating testicular development. In about 80 percent of XX males, the SRY gene is present on one of the X chromosomes. About 20 percent of those with 46 XX testicular disorder of sex development do not have the SRY gene. This form of the condition is called SRY-negative 46,XX testicular disorder of sex development.

Specimen: Peripheral Blood

Collection Container: Green Top (Sodium Heparin)

Desired Specimen Volume: 2 - 5 mL

Minimum Acceptable Volume: 1 mL

• Lithium heparin is not acceptable.
• Specimens must be collected in a sterile collection container.

Each specimen must be accompanied by a requisition form, script, electronic order or physician note. Each order must indicate the reason for testing (diagnosis).

• Transport to the laboratory at room temperature.
• Store specimen as whole blood, in original tube, at room temperature and deliver to lab within 24 hours.
• If specimen cannot be delivered within 24 hours, store in refrigerator. Do not freeze specimen.
• Specimens collected on the weekends must be refrigerated upon arrival at HNL Lab Medicine.

• Specimen frozen
• Specimen arriving without any form of patient identification (unlabeled)
• Specimen with attached needles
• Specimen arriving with broken or leaking collection tube
• Unfixed specimen treated with fixative

In a normal male cell , the expected signal pattern will be one aqua signal (X centomere), one green signal (Yq12), and one red signal (SRY). In a normal female cell, the expected signal pattern will be two aqua signals (X centromere). Individuals with a microdeletion will show one copy of the internal control aqua signal (X centromere), one copy of the Yq12 green signal, and no copy of the SRY red signal.

• FISH SRY
• Yp11.31
• Sex Reversal Y
• Sex-Determining Region

Slides are prepared per standard protocols. 20 metaphase cells are scored per probe. This FISH test is used as a supplement to standard G-banded chromosome analysis.

A standard karyotype can be completed to cytogenetically determine that an individual with a partial or complete male phenotype has an XX genotype.

The presence and location of the SRY gene can by determined using fluorescence in situ hybridization (FISH).

Deleted or Not Deleted or Duplicated. Nomenclature given is in accordance to the International System for Human Cytogenomic Nomenclature (ISCN, 2020). Concurrent interphase FISH will detect duplication of that gene of interest.