Deletion of b1/b3 shows risk for expanse of Yq microdeletion in male offspring: Case report of novel Y chromosome variations

Abstract

Rationale: This study aimed to report 1 family case with novel Y chromosome structural variations by an established next-generation sequencing (NGS) method using unique STSs.

Patient concerns: The case studied was from a family with a father and son (the proband). G-band staining was used for karyotype analysis. Y chromosome microdeletions were detected by sequence-tagged site (STS)-PCR analysis and a new NGS screening strategy.

Diagnoses: Semen analysis showed that the proband was azoospermic. The patient had an abnormal karyotype (45,X[48%]/46,XY[52%]). His father exhibited a normal karyotype. STS-PCR analysis showed that the proband had a deletion of the AZFb+c region, and his father had no deletion of STS markers examined. The sequencing method revealed that the patient had DNA sequence deletions from nt 20099846 to nt 28365090 (8.3 Mb), including the region from yel4 to the Yq terminal, and his father exhibited a deletion of b1/b3 and duplication of gr/gr.

Interventions: The proband was advised to undergo genetic counseling, and consider the use of sperm from a sperm bank or adoption to become a father.

Outcomes: The proband was azoospermic. AZFc partial deletions may produce a potential risk for large AZFb+c deletions or abnormal karyotypes causing spermatogenic failure in men.

Lessons: The NGS method can be considered a clinical diagnostic tool to detect Y chromosome microdeletions. The partial AZFc deletions and/or duplications can be a risk of extensive deletions in offspring.

Figure 1

STS-PCR results on Y chromosome microdeletions, Note: P means the proband. P-F means the probands father. + means presence of STSs. —means absence of STSs. In gel electrophoresis figures, P represents the patient or his father and C represents positive control.

Figure 2

The sequencing results of the patient and his father, Note: A: Copy number of probe signals of deletions on AZFb+c (yel4 to Yq terminal) in the proband. B: Copy number of probe signals showing deletions of b1/b3 combined with duplications of gr/gr in the probands father.