//Human Reproduction

Human Reproduction

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Articles of Interest

Deep sequencing shows that oocytes are not prone to accumulate mtDNA heteroplasmic mutations during ovarian ageing

Journal: Human Reproduction | Year: 2017

Abstract:

STUDY QUESTION
Does ovarian ageing increase the number of heteroplasmic mitochondrial DNA (mtDNA) point mutations in oocytes?

SUMMARY ANSWER
Our results suggest that oocytes are not subject to the accumulation of mtDNA point mutations during ovarian ageing.

WHAT IS KNOWN ALREADY
Ageing is associated with the alteration of mtDNA integrity in various tissues. Primary oocytes, present in the ovary since embryonic life, may accumulate mtDNA mutations during the process of ovarian ageing.

STUDY DESIGN, SIZE, DURATION
This was an observational study of 53 immature oocyte–cumulus complexes retrieved from 35 women undergoing IVF at the University Hospital of Angers, France, from March 2013 to March 2014. The women were classified in two groups, one including 19 women showing signs of ovarian ageing objectified by a diminished ovarian reserve (DOR), and the other, including 16 women with a normal ovarian reserve (NOR), which served as a control group.

PARTICIPANTS/MATERIALS, SETTING, METHODS
mtDNA was extracted from isolated oocytes, and from their corresponding cumulus cells (CCs) considered as a somatic cell compartment. The average mtDNA content of each sample was assessed by using a quantitative real-time PCR technique. Deep sequencing was performed using the Ion Torrent Proton for Next-Generation Sequencing. Signal processing and base calling were done by the embedded pre-processing pipeline and the variants were analyzed using an in-house workflow. The distribution of the different variants between DOR and NOR patients, on one hand, and oocyte and CCs, on the other, was analyzed with the generalized mixed linear model to take into account the cluster of cells belonging to a given mother.

MAIN RESULTS AND THE ROLE OF CHANCE
There were no significant differences between the numbers of mtDNA variants between the DOR and the NOR patients, either in the oocytes (P = 0.867) or in the surrounding CCs (P = 0.154). There were also no differences in terms of variants with potential functional consequences. De-novo mtDNA variants were found in 28% of the oocytes and in 66% of the CCs with the mean number of variants being significantly different (respectively 0.321, SD = 0.547 and 1.075, SD = 1.158) (P < 0.0001). Variants with a potential functional consequence were also overrepresented in CCs compared with oocytes (P = 0.0019). LARGE SCALE DATA N/A. LIMITATIONS, REASONS FOR CAUTION Limitations may be due to the use of immature oocytes discarded during the assisted reproductive technology procedure, the small size of the sample, and the high-throughput sequencing technology that might not have detected heteroplasmy levels lower than 2%. WIDER IMPLICATIONS OF THE FINDINGS The alteration of mtDNA integrity in oocytes during ovarian ageing is a recurring question to which our pilot study suggests a reassuring answer.

Peoples: - | Places: - | Topics: Older mothers and oocytes | DNA Type: mtDNA

Y chromosome microdeletions are not associated with spontaneous recurrent pregnancy loss in a Sinhalese population in Sri Lanka

Journal: Human Reproduction | Year: 2010

Abstract:

Many advances have been made in reproductive medicine, yet the spontaneous loss of a pregnancy remains the most common complication of pregnancy. The aetiology of spontaneous recurrent pregnancy loss (RPL) is multifactorial. Y chromosome microdeletions are found in ?7% of men with low sperm counts and, compared with the general population, a higher frequency of spontaneous pregnancy loss occurs in infertile couples. The current study was designed to examine whether Y chromosome microdeletions were associated with RPL in a Sinhalese population in Sri Lanka.METHODS The subjects were 76 male partners of couples where the female partner had experienced three or more RPLs. One hundred and twenty random males from the general population were also analysed as a control group. DNA extracted from peripheral blood was tested for Y chromosome microdeletions in the azoospermic factor (AZF), AZFa, AZFb, AZFc regions using a multiplex PCR amplification system. Partial deletions within the AZFc region were also tested.RESULTS None of the men (76 with RPL, and the 120 controls) had any microdeletions in the AZFa, AZFb, AZFc regions or partial deletions in the AZFc region.CONCLUSIONS Y chromosome microdeletions do not appear to be important in the aetiology of RPL in this population in Sri Lanka.

Peoples: - | Places: - | Topics: - | DNA Type: Y-DNA

2005-01-01T00:00:00+00:00 January 1st, 2005|