Table 1.

Details of included studies. NOA = non-obstructive azoospermia, obstructive azoospermia = OA, RT-PCR = real-time PCR, not mentioned = NM, upregulation = ↑, downregulation = ↓

Author year	Origin	Age	miRNA measurement technique	Sample type	Studied patients	Identified miRNAs/conclusion	REF
Lian et al. 2009	China	22–30	Microarray assay validation = RT-PCR	Testicular tissue	NOA = 3 Control = 2	Microarray = 19 ↑–154↓ Confirmed with RT-PCR= hsa-hsa-miR-302a, hsa-miR-491-3p, hsa-miR-520d-3p, hsa-miR-383	[21]
Wu et al. 2013	China	Case = 28.20 ± 4.02 Controls = 29.25 ± 3.03	TaqMan low density array validation = qRT–PCR	Sperm cell	NOA = 100 Control = 100	Hsa-miR-141↑, hsa-miR-429↑, hsa-miR-7-1-3p↑	[22]
Khosravi Mashizy et al. 2019	Iran	NM	RT-PCR	Testicular tissue	NOA = 40 Control = 40	let7↑	[45]
Abu-Halima et al. 2014	Germany	25.7 ± 3.6	Microarray assay validation = RT-PCR	Testicular tissue (compared with difference in histological pattern)	AZ = 56	hsa-mir-34b*, hsa-mir-34b, hsa-mir-34c-5p, hsa-mir-449a, and hsa-mir-449b	[39]
Abu-Halima et al. 2014	Germany	NM	RT-PCR	Testicular tissue	NOA = 40Control = 16	(hsa-miR-429) ↑ (hsa-miR-34b*, hsa-miR-34b, hsa-miR-34c-5p, hsa-miR-122) ↓	[40]
Zhou et al. 2019	China	Case = 26.40 ± 3.98 Control = 28.20 ± 3.56	RT-PCR	Sperm cell	AZ = 30 Control = 30	Hsa-miR-525-3p ↓	[23]
Tang et al. 2016	China	18–41	RT-PCR	Testicular tissue	NOA = 19 Control (OA) = 6	Hsa-miR-210 ↑	[24]
Zhang et al. 2019	China	Validation group: NOA = 31.000 ± 4.621 Control = 32.531 ± 5.858	Microarray assay validation = RT-PCR	Testicular tissue	Validation group: NOA = 32 Control = 32	Hsa- miR-10b-3p ↑ Hsa- miR-34b-5p ↓	[25]
Fang et al. 2018	China	22–45	Microarray assay validation = RT-PCR	Testicular tissue	SSR = 5 USR = 5 (All were from NOA patients)	miRNAs related to sperm function in both groups were identified.	[26]
Tang et al. 2018	China	post-cryptorchidopexy NOA = 23, 26, 28 post-cryptorchidopexy OA = 24, 25, 36	Next-generation sequencing (NGS) Validation = RT-PCR	Testicular tissue	Post-cryptorchidopexy NOA = 3 post-cryptorchidopexy OA = 3	152 miRNAs ↑ 297 miRNAs ↓	[27]
Barceló et al. 2018	Spain	21–45	Real-time PCR profiling Validation = RT-qPCR	Semen exosomes	AZ (spermatogenic failure) = 14 OA = 13 Control = 9	hsa-miR-539-5p and hsa-miR-941	[48]
Song et al. 2016	China	NM	RT-PCR	Testicular tissue	AZ = 16 Control = 8	Hsa-miR-188-3p	[28]
Yao et al. 2017	China	25–40	RNA deep sequencing Validation = RT-qPCR	Human spermatogonia, pachytene spermatocytes, round spermatids	OA = 20 NOA = 60	378 microRNAs were differentially expressed in human round spermatids between OA patients and NOA patients	[29]
Mostafa et al. 2016	Egypt	23–39	RT-PCR	Sperm cell	Normozoospermic = 52 Fertile normozoospermic Men with Vx = 43 Infertile OAT men without Vx = 62 Infertile OAT men with Vx = 63	hsa-miRNA-122, hsa-miRNA-181a, and hsa-miRNA-34c5 were positively correlated with sperm concentration, sperm motility, sperm morphology	[51]
Radtke et al. 2019	Germany	Case: 29.5 (11.5) Control: 36.5 (8.25) Median (IQR)	RT-PCR	Seminal plasma	Patient = 38 Control = 30	hsa-miR-371-a-3p is correlated with sperm concentration	[41]
Wu et al. 2012	China	25.42–33.41	RT-PCR	Seminal plasma	NOA = 96 OS = 96 Control = 96	hsa-miR-19b let-7a ↑	[30]
Boellaard et al. 2019	Netherlands	NM	RT-PCR	Sperm cell	Different samples from urogenital tract	hsa-miR-371a-3p related to sperm concentration	[52]
Abu-Halima et al. 2012	Germany	N = 32.78 ± 5.63 AZS = 34.67 ± 7.87 OA = 31.33 ± 3.94	Microarray assay Validation = RT-PCR	Sperm cell	N = 9 AZS = 9 OA = 9	AS = hsa-miR-34b, hsa-miR-122, hsa-miR-1973 OA = hsa-miR-34b, hsa-miR-34b*, hsa-miR-15b, hsa-miR-34c-5p, hsa-miR-122, hsa-miR-449a, hsa-miR-1973, hsa-miR-16, and hsa-miR-19a	[42]
Abhari et al. 2014	Iran	27.5 ± 4.8	RT-PCR	Sperm cell	OS = 43 Control = 43	hsa-miR-21, hsa-miR-22 ↑	[46]
Li et al. 2016	China	OS = 23–37 OA = 25–28	Microarray assay Validation = RT-PCR	Testicular tissue	OS = 3 OA = 3	33 DE-hsa-miRNAs	[31]
Abu-Halima et al. 2019	Germany	20–35	RT-PCR Validation = RT-PCR	Sperm cell	OAS = 33 Control = 33	hsa-miR-23a/b-3p ↑	[43]
Tian et al. 2017	China	20–45	RT-PCR	Sperm cell	AZS = 36 OS = 36 AZ = 36 OSAS = 36	hsa-miR-10a, hsa-miR-10b, hsa-miR-135a, hsa-miR-135b, hsa-miR-888, hsa-miR-891a ↓	[32]
Abu-Halima et al. 2016	Germany	24–39	RT-PCR Validation = RT-PCR	Semen exosomes	OAS = 12 Control = 12	hsa-miR-765 and hsa-miR-1275 ↑ hsa-miR-15a ↓	[44]
Zhou et al. 2015	China	N = 29.00 ± 4.804 AZS = 30.13 ± 5.841	RT-PCR	Sperm cell	ASZ = 48Control = 42	hsa-miR-27b ↓	[33]
Zhou et al. 2015	China	NM	RT-PCR	Seminal plasma	AZS = 50 Control = 50	hsa-miR-101-3p, let-7b-5p ↓ sp-miR-151a-5p ↑	[34]
Wang et al. 2011	China	AZ = 29.07 ± 4.67 AZS = 29.41 ± 4.35 OS = 28.82 ± 5.31 Control = 28.63 ± 4.40	RT-PCR	Seminal plasma	AZ = 73 AZS = 79 OS = 34 Control = 68	AZ = hsa-miR-34c-5p, hsa-miR-122, hsa-miR-146b-5p, hsa-miR-181a, hsa-miR-374b, hsa-miR-509–5p, and hsa-miR-513a-5p ↓ AZS = hsa-miR-34c-5p, hsa-miR-122, hsa-miR-146b-5p, hsa-miR-181a, hsa-miR-374b, hsa-miR-509–5p, and hsa-miR-513a-5p ↑	[35]
Qing et al. 2017	China	AZS = 33.73 ± 6.63 N = 33.00 ± 7.22	RT-PCR	Seminal plasma	AZS = 22 N = 22	hsa-miR-891b, hsa-miR-892b, hsa-miR-892a, hsa-miR-888, hsa-miR-890	[36]
Zhou et al. 2018	China	NM	TaqMan low-density array Validation = RT-PCR	Seminal plasma	AZS = 50 N = 50	let-7b-5p ↓	[37]
Heidary et al. 2018	Iran	AZS = 36.7 ± 6.87 Control = 35.7 ± 5.05	Illumina high-throughput sequencing Validation = RT-PCR	Sperm cell	AS = 39 Control = 35	Hsa-miR-888-3p ↑	[47]
Salas-Huetos et al. 2014	Spain	NM	TaqMan array	Sperm cell	10 males with normal seminogram	None of the miRNAs correlated with sperm motility, morphology or concentration	[53]
Zhou et al. 2017	China	AZS = 33.30 ± 1.46 Control = 29.60 ± 1.05	RT-PCR	Sperm cell	AZS = 20 Control = 20	hsa-miR-27a ↑	[38]
Salas-Huetos et al. 2015	Spain	19–50	RT-PCR	Sperm cell	AZS = 10 TS = 10 OS = 10	AZS = 32 DE-miRNAs TS = 19 DE-miRNAs OS = 18 DE-miRNAs	[49]
Corral-Vazquez et al. 2019	Spain	NM	RT-PCR	Sperm cell	AZS = 10 TS = 10 OS = 10	AZS = hsa-miR-942-5p/hsa-miR-1208 TS = hsa-miR-296-5p/hsa-miR-328-3p OS = hsa-miR-139-5p/hsa-miR-1260a	[50]