الفهرس 
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Abstract
Reduced male fertility can be the result of congenital and acquired urogenital abnormalities, infections of the genital tract, increased scrotal temperature (varicocele), endocrine disturbances, genetic abnormalities and immunological factors . No causal factor is found in 60-75% of cases (idiopathic male infertility). These men present with no previous history associated with fertility problems and have normal findings on physical examination and endocrine laboratory testing. Semen analysis reveals a decreased number of spermatozoa oligozoospermia), decreased motility (asthenozoospermia) and many abnormal forms on (morphological examination (teratozoospermia). These abnormalities usually occur together and are described as the oligoastheno- teratozoospermia (OAT) syndrome. Unexplained forms of male infertility may be caused by several factors, such as chronic stress, endocrine disruption due to environmental pollution, reactive oxygen species and genetic abnormalities (Crosignani et al., 1993). Methylenetetrahydrofolate reductase (MTHFR) is responsiple for homocysteine metabolism. Single nucleotide polymorphisms (SNPs) of MTHFR gene were implicated in the pathogenesis of DN in many ethnic groups. Two common SNPs of the MTHFR gene have been identified: C677T and A1298C. Subjects included in this case-controlled cross-sectional study constituted 100 cases of men infertility in addition to 90 subjects as healthy controls. They were recruited from Mansoura University, Egypt . After obtaining 3ml peripheral blood was collected from all cases as well as controls in tubes containing EDTA solution as anticoagulant. DNA was extracted from the whole blood using capture column kits extraction and purification kit (Gentra systems, USA). Analysis was carried out for four cytokine gene polymorphisms including, C677T and A1298C polymorphisms using polymerase chain reaction with sequence-specific primers (SSP-PCR). PCR amplification was performed in two SSP-PCR reactions employing C677T and A1298C polymorphisms using polymerase chain reaction. Detection of amplified product was done by loading into a 3% agarose gel containing ethidum bromide. Gels were electrophoresed for 20 minutes at 200v. The gels were then photographed under UV light (320 nm) and scored for the presence or absence of an allele specific band providing a PCR control band was present. This study revealed that male infertility cases had a significantly lower frequency of the heterozygous mutated CT genotype of C677T polymorphism compared to controls (31.0% vs. 55.5%, p =0.0007), while they had a significantly higher frequency of the homozygous mutated TT genotype of C677T polymorphism (33% vs. 0.0%, p=<0.0001). On the other hand they had a significantly lower frequency of heterozygous mutated AC genotype and C allele of A1298C polymorphism compared to controls (33.7% vs. 45.2%, p=0.012 and 22.8% vs. 31.9%, p=0.002, respectively), while they had a significantly higher frequency of wild AA genotype and A allele of A1298C polymorphism compared to controls (60.4% vs. 45.5%, p=0.001 and 77.2% vs. 68.1%, p=0.002, respectively). Regarding to their types as regard their studied genotypes, it is noted that cases had a significant higher frequency of the homozygous mutated TT genotype of C677T polymorphism ( p= <0.0001). On the other hand types of cases had significantly higher frequency of homozygous mutated CC genotype of MTHFR A1298C polymorphism (p=<0.0001). Analyzing studied Egyptian cases for combined genotypes regarding their combined genotypes of C677T and A1298C polymorphisms of MTHFR gene, it is noted that cases had a significantly higher frequency of combined (CC and AA) genotypes compared to controls (p= 0.003). Also, they had a significantly higher frequency of (CC and CC) genotypes compared to controls (p= 0.03).while they had a higher frequency of combined (CT and AA) genotypes ( p= <0.0001). Also, they had a significantly higher frequency of (TT and AC) genotypes compared to controls (p= <0.0001).Also, cases had a significantly higher frequency of combined (TT and AA) genotypes compared to controls (p= 0.01). while they had a higher frequency of combined (TT and CC) genotypes ( p= 0.01).