Preimplantation genetic testing for mitochondrial DNA mutation: ovarian response to stimulation, outcomes and follow-up.

RESEARCH QUESTION: How do carriers of pathogenic mitochondrial DNA (mtDNA) respond to ovarian stimulation? DESIGN: A single-centre, retrospective study conducted between January 2006 and July 2021 in France. Ovarian reserve markers and ovarian stimulation cycle outcomes were compared for couples undergoing preimplantation genetic testing (PGT) for maternally inherited mtDNA disease (n = 18) (mtDNA-PGT group) with a matched-control group of patients undergoing PGT for male indications (n = 96). The PGT outcomes for the mtDNA-PGT group and the follow-up of these patients in case of unsuccessful PGT was also reported. RESULTS: For carriers of pathogenic mtDNA, parameters of ovarian response to FSH and ovarian stimulation cycle outcomes were not different from those of matched-control ovarian stimulation cycles. The carriers of pathogenic mtDNA needed a longer ovarian stimulation and higher dose of gonadotrophins. Three patients (16.7%) obtained a live birth after the PGT process, and eight patients (44.4%) achieved parenthood through alternative methods: oocyte donation (n = 4), natural conception with prenatal diagnosis (n = 2) and adoption (n = 2). CONCLUSION: To the best of our knowledge, this is the first study of women carrying a mtDNA variant who have undergone a PGT for monogenic (single gene defects) procedure. It is one of the possible options to obtain a healthy baby without observing an impairment in ovarian response to stimulation.

Reproductive functions and fertility preservation in transgender women: a French case series.

RESEARCH QUESTION: The reproductive potential of transgender people may be impaired by gender-affirming hormone treatment (GAHT) and is obviously suppressed by gender-affirming surgery involving bilateral orchiectomy. The evolution of medical support for transgender people has made fertility preservation strategies possible. Fertility preservation in transgender women mainly relies on sperm cryopreservation. There are few studies on this subject, and the sample sizes are small, and so it difficult to know whether fertility preservation procedures are feasible and effective in trans women. DESIGN: This retrospective study reports the management of fertility preservation in transgender women referred to the study centre for sperm cryopreservation, and the semen parameters of trans women were compared with those of sperm donors. RESULTS: Ninety-six per cent of transgender women who had not started treatment benefitted from sperm cryopreservation, compared with 80% of those who attempted a therapeutic window and 50% of those receiving hormonal treatment at the time of sperm collection. No major impairment of semen parameters was observed in transgender women who had not started GAHT compared with sperm donors. However, even though the frequency of oligozoospermia was no different, two transgender women presented azoospermia. Some transgender women who had started GAHT could benefit from sperm freezing. None of them were treated with gonadotrophin-releasing hormone (GnRH) analogues. CONCLUSIONS: Parenthood strategies for transgender people have long been ignored, but this is an important issue to consider, especially because medical treatments and surgeries may be undertaken in adolescents or very young adults. Fertility preservation should ideally be offered prior to initiation of GAHT.

Hypophosphatasia: a genetic-based nosology and new insights in genotype-phenotype correlation.

Hypophosphatasia (HPP) is caused by pathogenic variants in the ALPL gene. There is a large continuum in the severity, ranging from a lethal perinatal form to dental issues. We analyzed a cohort of 424 HPP patients from European geographic origin or ancestry. Using 3D modeling and results of functional tests we classified ALPL pathogenic variants according to their dominant negative effect (DNE) and their severity. The cohort was described by the genotypes resulting from alleles s (severe recessive), Sd (severe dominant), and m (moderate). Many recurrent variants showed a regional anchor pointing out founder effects rather than multiple mutational events. Homozygosity was an aggravating factor of the severity and moderate alleles were rare both in number and frequency. Pathogenic variants with DNE were found in both recessive and dominant HPP. Sixty percent of the adults tested were heterozygous for a variant showing no DNE, suggesting another mechanism of dominance like haploinsufficiency. Adults with dominant HPP without DNE were found statistically less severely affected than adults with DNE variants. Adults with dominant HPP without DNE represent a new clinical entity mostly diagnosed from 2010s, characterized by nonspecific signs of HPP and low alkaline phosphatase, and for which a high prevalence is expected. In conclusion, the genetic composition of our cohort suggests a nosology with 3 clinical forms: severe HPP is recessive and rare, moderate HPP is recessive or dominant and more common, and mild HPP, characterized by low alkaline phosphatase and unspecific clinical signs, is dominantly inherited and very common.