June 2018 — Molecular Diagnostics 1
A 33-year-old man presented with a history of infertility. A blood sample was submitted to the laboratory for molecular analysis of Y chromosome microdeletions. Analysis of Y chromosome markers by polymerase chain reaction (PCR) (Fig. 1) produced the results seen in Fig. 2 for the AZFa, AZFb, and AZFc regions. Subsequent chromosome analysis was performed, and a representative karyogram is shown in Fig. 3.
Figure 1. Overview of Y chromosome markers assessed in the microdeletion test. Pool 1 is composed of markers SY254, SY86 and SY127 (green boxes). Pool 2 is composed of markers SY84, SY134 and SY255 (blue boxes).
Figure 2.A) PCR reaction with Pool 1 markers. B.) PCR reaction with Pool 2 markers. Corresponding AZF regions are pointed out by arrows. Hemoglobin subunit gamma 2 (HGB2) was used as the housekeeping control gene. Analyzed samples in this run include 10 individuals, marked P1-P10. The case referred to in this discussion corresponds to P6*. Normal control corresponds to the sample of a normal fertile man. Positive control corresponds to a DNA sample of a normal female. Negative control corresponds to a no-template reaction. Ladder used is pGem ® from Promega.
Figure 3. Representative karyogram of P6*. ISCN nomenclature is omitted from this picture to allow trainees to practice identification of chromosome rearrangements. See the answers section to find out the identified chromosome abnormalities. A zoomed-in picture of the Y chromosome is shown to facilitate structure analysis.
Cinthya Zepeda Mendoza, Ph.D.
Fellow, Laboratory Genetics and Genomics
Kandelaria Rumilla, M.D.
Consultant, Laboratory Genetics and Genomics
Assistant Professor of Laboratory Medicine and Pathology
Mayo Clinic College of Medicine