JBRA Assist. Reprod. 2020;24(4):510-512
CASE REPORT
doi: 10.5935/1518-0557.20200022
Complex Y chromosome anomalies in an infertile male
1Department of Cytogenetics, Lanka Hospitals Diagnostics, Sri Lank
2Faculty of Medicine, University of Kelaniya, Sri Lanka
The authors have no conflict of interest to declare.
ABSTRACT
Y chromosome anomalies are closely associated with non-obstructive azoospermia
(NOA), a major etiology in male infertility. Klinefelter syndrome (KS) and Y
chromosome microdeletions are some of the well-identified genetic defects in
this regard, while Y chromosome aneuploidies have been reported to be
susceptive. We report the rare case of a patient presenting with three complex
genetic defects: mosaic Y chromosome aneuploidy; loss of the heterochromatin
region in the q arm of the Y chromosome (Yqh-); and azoospermia factor C
subregion (AZFc) microdeletion. The patient reported he had been subfertile for
five years. Semen analysis confirmed total azoospermia along with an unaffected
hormonal profile for serum follicle stimulating hormone (FSH), luteinizing
hormone (LH), and prolactin levels. Since the microdeletion analysis of
azoospermia factor (AZF) region revealed the presence of three microdeletions in
the AZFc region, the patient was offered intracytoplasmic sperm injection (ICSI)
upon the retrieval of sperm by testicular sperm extraction (TESE) as the best
possible assisted reproductive treatment (ART) option. It was further suggested
to carry out pre-implantation genetic screening (PGS) in order to facilitate the
transfer of only female embryos, thus preventing the dissemination of Y
chromosomal anomalies.
Keywords: male infertility, Y chromosome anomalies, azoospermia, AZF microdeletion
INTRODUCTION
Infertility is a global problem in which males account for 20-70% of affected
partners. Though etiologies for male factor subfertility are multiple and
multifactorial, genetic causes have increasingly been recognized as one of the main
causes recently (Tournaye et al.,
2017). Male infertility is closely associated with Y chromosome anomalies
resulting in defective gonadal development and spermatogenesis (Küçükaslan et al., 2013).
Non-obstructive azoospermia (NOA) has been defined as “absent sperms in the
ejaculate due to failure of spermatogenesis” and thought to be closely associated
with genetic anomalies (Fogle et
al., 2006). In addition, the higher prevalence of abnormal
karyotypes among patients with azoospermia or severe oligospermia justifies the need
for extensive genetic profiling of such affected patients (Chiba et al., 2016). Management of these
patients is entirely based on ART and has very little scope unless they are coupled
with ICSI and TESE (Chan et al., 2001). Therefore, male factor subfertility needs to be properly
investigated with the objective of fleshing out the exact etiology, so that the best
ART option can be offered. This paper reports the case of a patient with
non-obstructive azoospermia and three genetic defects: mosaic Y chromosome
aneuploidy; Y qh- deletion; and AZFc microdeletion, one of the rarest defects.
CASE DESCRIPTION
A 37-year-old male came to the subfertility clinic claiming he had been subfertile
for five years. The patient gave a vague account in which he stated he had mumps at
the age of 11 and reached spermarche in his early teens. There was no significant
family history of subfertility and his own brother was married and had two healthy
children. Physical examination findings indicate he was a healthy adult with a body
mass index (BMI) of 23.5 kg/m2 without evidence of gynecomastia. He had a normal
phallus and bilaterally descended testes graded as Tanner V. There was no evidence
of varicocele or hydrocele. The patient underwent detailed hormonal, genetic, and
seminal fluid analysis.
Hormone assays
Complete analysis of hypothalamic-pituitary axis was performed based on serum
FSH, LH, and prolactin levels. The patient had a marginally elevated serum FSH
level [11.31mIu/ml (0.7-11.1)] along with normal prolactin [367.71mIU/L
(70-410)] and LH [4.11mIu/ml] levels.
Semen analysis
Comprehensive semen analysis carried out twice showed the patient had azoospermia
with normal macroscopic appearance and insignificant amount of other cellular
components.
Cytogenetic analysis
Peripheral blood lymphocytes were cultured and harvested as per the original
protocol described by Moorhead et
al. (1960). A total of 20 metaphases with GTG banded
chromosomes were analyzed and karyotypes were reported in accordance with the
guidelines of the International System for Cytogenomic Nomenclature (ISCN) 2016.
Chromosome analysis of 20 metaphases from cultured peripheral blood using GTG
banding revealed a karyotype of 45,X[7]/46,XYqh-[13] (Figure 1).
Figure 1. GTG analysis of metaphases showing loss of Y or Monosomy X, i.e.
45,X (left) and a loss of the heterochromatin region in the q arm of
the Y chromosome, i.e. 46,X,Yqh- (right).
Fluorescence in situ hybridization (FISH)
Cultured peripheral lymphocytes were harvested, mounted, and fixed on previously
coded slides. FISH was performed using a MetaSystems XCyting Centromere
Enumeration Probe for Chromosome X and Y on cultured interphase nuclei. A total
number of 200 cells were analyzed by two observers and the presence of Y
chromosome mosaicism was confirmed in 35% of the cell population having 45X
chromosome complement (Figure 2).
Figure 2. FISH analysis of interphase nuclei with specific centromeric
probes for chromosome X (green) and Y (red), showing loss of Y or
Monosomy X (left) and a normal signal male pattern (right).
Detection of AZFa, b, and c subregion microdeletion
Presence of Yqh- in the karyotype drove Y chromosome microdeletion analysis.
Molecular genetic analysis was carried out using a multiplex polymerase chain
reaction (PCR) method targeting the following sequence-tagged sites (STS): AZFa:
sY81, sY84s, Y86, sY182; AZFb: sY114, sY121, sY124, sY127, sY128, sY129, sY130,
sY133, sY134, sY143, sYPR3, RBMY1; and AZFc: sY149, sY153, sY157, sY158, sY208,
sY242, sY254, sY255, sY145, SY147, sY152. The test found microdeletions in the
AZFc subregion (sY254, sY157, sY145) associated with varying phenotypes.
DISCUSSION
More than 30 million men worldwide are estimated to suffer from infertility with
significant genetic predispositions affecting both spermatogenesis and androgenesis
(Tournaye et al., 2017).
Sex chromosome anomalies such as KS, and certain autosomal abnormalities are
reportedly important in this regard. In the present case, we observed a karyotype of
mosaic Y chromosome aneuploidy along with a polymorphic variant in the long (q) arm
of the Y chromosome 45,X[7]/46,X,Yqh-[13]. Results of FISH also confirmed the
presence of Y chromosome aneuploidy in 35% of the analyzed cell population. Mosaic Y
chromosome aneuploidy 45,X/ 46,XY is a rare chromosomal abnormality which gives rise
to varying phenotypic features of gonadal development such as expression of a female
phenotype, indefinite genitals, or a male with hypospadias or azoospermia (Chiba et al., 2016). The extent
of Y chromosome mosaicism observed in this patient gave rise to an apparently normal
male phenotype with azoospermia.
The 46,XYqh- karyotype is a common polymorphic variant that occurs in the general
population with no significant clinical implications (Gao et al., 2017). Most of these polymorphic variants
represent either loss or gain in heterochromatin regions of the same chromosome that
is genetically silent. The sex determining gene (SRY) and the AZF-a, b and c
subregions, which respectively reside in the p and q arms of chromosome Y, are
involved in male gonadal development and spermatogenesis (Liu et al., 2016). Reports have cited loss of
the heterochromatin region in the q arm of the Y chromosome and speculated around
the involvement of the AZF region, which directed microdeletion analysis to the AZF
region.
The AZF region in the q arm of the Y chromosome plays an important role in
spermatogenesis and differentiation (Samli et
al., 2006). The presence of five recombination hotspots in
the q arm of the Y chromosome and their unusual molecular arrangement has made this
particular region more prone to deletion. Three clinically recognizable
submicroscopic deletions have been identified in the AZFa, AZFb, and AZFc subregions
(Tournaye et al., 2017; Zorrilla & Yatsenko, 2013). Complete
or partial deletion of these subregions has been clearly associated with azoospermia
or severe oligozoospermia unrelated to the testicular phenotype (Tournaye et al., 2017).
Identification of these submicroscopic deletions has great diagnostic and prognostic
value. Men with complete AZFa, and AZFb deletions do not have spermatozoa during a
TESE procedure, whereas men with AZFc deletion - although they have virtually zero
spermatozoa in the ejaculate - may have some spermatozoa in testicular tissues
(Zhang et al., 2013).
The proband in this reported case had AZFc deletion and might be a candidate for in
vitro fertilization (IVF) and PGS after TESE (Zorilla & Yatsenko, 2013). This would enable the
couple to transfer only female embryos rather than an embryo with the 46,XYqh-
anomaly, thus preventing the transmission of the Y chromosome microdeletion.
Therefore, AZF microdeletion analysis should be carried out when a loss of q arm
heterochromatin region in Y chromosome is detected.
Therefore, genetic testing is mandatory whenever a patient presents with azoospermia.
Baseline karyotyping is essential in order to rule out sex chromosome aneuploidies.
Understanding the nature of Y chromosome microdeletions may optimize patient
management and enable the choice of the best possible method of ART.
ACKNOWLEDGEMENTS
The authors acknowledge the support of Lanka Hospitals Diagnostics in carrying out
this study.
REFERENCES
Chan PT, Palermo GD, Veeck LL, Rosenwaks Z, Schlegel PN. Testicular
sperm extraction combined with intracytoplasmic sperm injection in the treatment
of men with persistent azoospermia postchemotherapy. Cancer. 2001;92:1632-7.
PMID: 11745242 DOI:
10.1002/1097-0142(20010915)92:6<1632::AID-CNCR1489>3.0.CO;2-I
Medline Crossref
Chiba K, Enatsu N, Fujisawa M. Management of non-obstructive
azoospermia. Reprod Med Biol. 2016;15:165-73. PMID: 29259433 DOI:
10.1007/s12522-016-0234-z
Medline Crossref
Fogle RH, Steiner AZ, Marshall FE, Sokol RZ. Etiology of azoospermia
in a large nonreferral inner-city population. Fertil Steril. 2006;86:197-9.
PMID: 16753159 DOI: 10.1016/j.fertnstert.2005.12.047
Medline Crossref
Gao M, Pang H, Zhao YH, Hua J, Tong D, Zhao H, Liu Y, Zhao Y, Zhang
M, Yan XJ, Chen H, Ma HP, Jin TY, Dong SL. Karyotype analysis in large sample
cases from Shenyang Women’s and Children’s hospital: a study of 16,294 male
infertility patients. Andrologia. 2017;49:e12649. PMID: 27397756 DOI:
10.1111/and.12649
Medline Crossref
Küçükaslan AŞ, Çetintaş VB, Altıntaş R,
Vardarlı AT, Mutlu Z, Ulukuş M, Semerci B, Eroğlu Z.
Identification of Y chromosome microdeletions in infertile Turkish men. Turk J
Urol. 2013;39:170-4. PMID: 26328103 DOI: 10.5152/tud.2013.035
Medline Crossref
Liu XG, Hu HY, Guo YH, Sun YP. Correlation between Y chromosome
microdeletion and male infertility. Genet Mol Res. 2016;15:gmr8426. PMID:
27323142 DOI: 10.4238/gmr.15028426
Medline Crossref
Moorhead PS, Nowell PC, Mellman WJ, Battips DT, Hungerford DA.
Chromosome preparations of leukocytes cultured from human peripheral blood. Exp
Cell Res. 1960;20:613-6. PMID: 13772379 DOI:
10.1016/0014-4827(60)90138-5
Medline Crossref
Samli H, Samli MM, Azgoz A, Solak M. Y chromosome microdeletion in a
case with Klinefelter’s Syndrome. Arch Androl. 2006;52:427-31. DOI:
10.1080/01485010600840780
Crossref
Tournaye H, Krausz C, Oates RD. Novel concepts in the aetiology of
male reproductive impairment. Lancet Diabetes Endocrinol. 2017;5:544-53. PMID:
27395771 DOI: 10.1016/S2213-8587(16)30040-7
Medline Crossref
Zhang F, Li L, Wang L, Yang L, Liang Z, Li J, Jin F, Tian Y.
Clinical characteristics and treatment of azoospermia and severe oligospermia
patients with Y-chromosome microdeletions. Mol Reprod Dev. 2013;80:908-15. PMID:
24002933 DOI: 10.1002/mrd.22226
Medline Crossref
Zorrilla M, Yatsenko AN. The Genetics of Infertility: Current Status
of the Field. Curr Genet Med Rep. 2013;1:247-60. PMID: 24416713 DOI:
10.1007/s40142-013-0027-1
Medline Crossref