Idiopathic male infertility is strongly associated with aberrant DNA methylation of imprinted loci in sperm: a case-control study

Table 1 Characteristics of idiopathic infertile males and fertile controls

Characteristic	Controls (n = 59)^a	Cases
Characteristic	Controls (n = 59)^a	Case 1 (n = 39)^b	Case 2 (n = 45)^c	Case 3 (n = 51)^d	Case all (n = 135)^e
Age (years, mean ± SD)	29.08 ± 3.85	29.85 ± 4.84	28.71 ± 3.91	28.78 ± 4.07	29.07 ± 4.25
BMI (kg/m², mean ± SD)^f	23.93 ± 4.17	22.61 ± 3.54	22.99 ± 2.72	22.92 ± 3.36	22.86 ± 3.20
Smoking status [n (%)]
No	27 (45.8)	21 (53.8)	26 (57.8)	23 (45.1)	70 (51.9)
Yes	32 (54.2)	18 (46.2)	19 (42.2)	28 (54.9)	65 (48.1)
Alcohol drinking [n (%)]
No	46 (78.0)	33 (84.6)	37 (82.2)	41 (80.4)	111 (82.2)
Yes	13 (22.0)	6 (15.4)	8 (17.8)	10 (19.6)	24 (17.8)
Abstinence time [n (%)]
< 4	15 (25.4)	7 (18.3)	10 (23.8)	4 (12.1)	21 (15.6)
4–7	38 (64.4)	41 (68.3)	24 (57.1)	23 (69.7)	88 (65.2)
≥ 7	6 (10.2)	12 (13.3)^g	8 (19.0)	6 (18.2)	26 (19.3)
Ejaculate volume (ml, mean ± SD)	4.29 ± 1.32	2.99 ± 1.21^g	3.30 ± 1.60^g	3.43 ± 1.47^g	3.26 ± 1.45^g
Sperm concentration (10⁶/ml, mean ± SD)	49.52 ± 33.85	76.92 ± 54.36^g	14.62 ± 2.91^g	4.35 ± 2.75^g	28.74 ± 42.58^g
Sperm motility (%, mean ± SD)	57.00 ± 16.05	53.81 ± 26.54	39.59 ± 20.12^g	31.48 ± 14.70^g	40.64 ± 22.27^g

^aControl: fertile men
^bCase 1: idiopathic infertile men with normozoospermia (sperm concentration ≥ 20 × 10⁶/ml)
^cCase 2: idiopathic infertile men with moderate oligozoospermia (sperm concentration 5–20 × 10⁶/ml)
^dCase 3: idiopathic infertile men with severe oligozoospermia (sperm concentration < 5 × 10⁶/ml)
^eCase all: the sum of case 1, case 2, and case 3
^fBMI body mass index
^gP < 0.05 when compared between case and control groups

ISSN: 1868-7083