Increased sperm mitochondrial DNA content in male infertility

ISSN： 1460-2350

Source： Human Reproduction, Vol.18, Iss.3, 2003-03, pp. : 550-556

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Abstract

BACKGROUND: There is increasing evidence that mitochondrial DNA (mtDNA) anomalies in sperm may lead to infertility. Point mutations, deletions and the presence of a specific mtDNA haplogroup have been associated with poor sperm quality, but little attention has been paid to the role of mtDNA content. METHODS: Using density gradient separation and swim‐up methods, we selected motile sperm from 32 normal and 35 abnormal sperm samples. The mtDNA/‐globin gene ratio was determined by real‐time quantitative PCR. RESULTS: The average mtDNA/‐globin ratio of sperm collected from 100% density layers was 1.4 for normal sperm, 6.1 for sperm samples presenting at least one abnormal criterion [among the three criteria established by World Health Organization (1999), i.e. sperm count, motility and morphology], and 9.1 for sperm samples presenting two or more of these abnormal criteria. These differences are very highly significant (P < 0.0001).="" the="" mtdna="" numbers="" were="" also="" much="" greater="" in="" sperm="" collected="" from="" the="" 40%="" density="" gradient="" layers="" (mean:="" 17.1,="">P < 0.001),="" known="" to="" contain="" the="" most="" abnormal="" sperm="" of="" the="" sperm="" samples,="" than="" in="" those="" collected="" from="" the="" 100%="" layers="" known="" to="" contain="" sperm="" with="" the="" best="" fertilizing="" ability.="" conclusion:="" our="" results="" showed="" significant="" mtdna="" amplification="" in="" sperm="" collected="" from="" abnormal="" sperm="" samples.="">