Preimplantation genetic diagnosis in genomic regions with duplications and pseudogenes: long-range PCR in the single-cell assay

State of the Science and Ethical Considerations for Preimplantation Genetic Testing for Monogenic Cystic Kidney Diseases and Ciliopathies

There is a broad phenotypic spectrum of monogenic polycystic kidney diseases (PKDs). These disorders often involve cilia-related genes and lead to the development of fluid-filled cysts and eventual kidney function decline and failure. Preimplantation genetic testing for monogenic (PGT-M) disorders has moved into the clinical realm. It allows prospective parents to avoid passing on heritable diseases to their children, including monogenic PKD. The PGT-M process involves embryo generation through in vitro fertilization, with subsequent testing of embryos and selective transfer of those that do not harbor the specific disease-causing variant(s). There is a growing body of literature supporting the success of PGT-M for autosomal-dominant and autosomal-recessive PKD, although with important technical limitations in some cases. This technology can be applied to many other types of monogenic PKD and ciliopathies despite the lack of existing reports in the literature. PGT-M for monogenic PKD, like other forms of assisted reproductive technology, raises important ethical questions. When considering PGT-M for kidney diseases, as well as the potential to avoid disease in future generations, there are regulatory and ethical considerations. These include limited government regulation and unstandardized consent processes, potential technical errors, high cost and equity concerns, risks associated with pregnancy for mothers with kidney disease, and the impact on all involved in the process, including the children who were made possible with this technology.

Factors influencing the clinical outcome of preimplantation genetic testing for polycystic kidney disease

STUDY QUESTION

What are the factors influencing the success rate for couples undergoing preimplantation genetic testing (PGT) for polycystic kidney disease (PKD)?

SUMMARY ANSWER

In our study cohort, the live birth delivery rate is significantly associated with female age while the male infertility accompanying autosomal dominant PKD (ADPKD) does not substantially affect the clinical outcome.

WHAT IS KNOWN ALREADY

While women with ADPKD have no specific fertility problems, male ADPKD patients may present with reproductive system abnormalities and infertility.

STUDY DESIGN, SIZE, DURATION

This retrospective cohort study involves 91 PGT cycles for PKD for 43 couples (33 couples for PKD1, 2 couples for PKD2 and 8 couples for autosomal recessive PKD (ARPKD)) from January 2005 until December 2016 with follow-up of transfers until end of 2017.

PARTICIPANTS/MATERIALS, SETTING, METHODS

Sixteen single-cell clinical tests for PKD based on multiplex PCR of short tandem repeat markers, with or without a specific mutation were developed and applied for diagnosis of 584 Day 3 cleavage stage embryos. In 18 couples, the male partner was affected with ADPKD (=Group A) and 12 of them had a documented infertility status. Group A underwent 52 cycles to oocyte retrieval. For 18 other couples, the female partner was affected with ADPKD (=Group B) and four male partners from this group had a documented history of infertility. This group underwent 31 cycles to OR.

MAIN RESULTS AND THE ROLE OF CHANCE

Genetic analysis resulted in 545 embryos (93.3%) with a diagnosis, of which 215 (36.8%) were genetically transferable. Transfer of 74 embryos in 53 fresh cycles and of 34 cryopreserved embryos in 33 frozen-warmed embryo transfer cycles resulted in a live birth delivery rate of 38.4% per transfer with 31 singleton live births, two twin live births and one ongoing pregnancy. The observed cumulative delivery rate was 57.8% per couple after five treatment cycles. Thirty cryopreserved embryos still remain available for transfer. The clinical pregnancy rate per transfer (fresh + frozen; 45.9% in group A versus 60.0% in group B, P < 0.05) and the live birth delivery rate per transfer (fresh + frozen; 27.0% in group A versus 42.9% in group B, P < 0.05) was significantly lower for couples with the male partner affected with ADPKD compared with couples with the female partner affected with ADPKD. However, a multivariate logistic regression analysis showed that only female age was associated with live birth delivery rate (odds ratio = 0.87; 95% CI: 0.77-0.99; P = 0.032).

LIMITATIONS, REASONS FOR CAUTION

This study is based on retrospective data from a single centre with Day 3 one-cell and two-cell biopsy. Further analysis of a larger cohort of PKD patients undergoing PGT is required to determine the impact of male infertility associated with ADPKD on the cumulative results.

WIDER IMPLICATIONS OF THE FINDINGS

Knowledge about factors affecting the clinical outcome after PGT can be a valuable tool for physicians to counsel PKD patients about their reproductive options. Males affected with ADPKD who suffer from infertility should be advised to seek treatment in time to improve their chances of conceiving a child.

STUDY FUNDING/COMPETING INTEREST(S)

No funding was obtained. There are no competing interests to declare.

TRIAL REGISTRATION NUMBER

Not applicable.

A novel inhibitor of nuclear factor kappa-B kinase subunit gamma mutation identified in an incontinentia pigmenti patient with syndromic tooth agenesis

OBJECTIVE

To explore the gene mutation in an incontinentia pigmenti (IP) patient with syndromic tooth agenesis.

METHODS

Long-range polymerase chain reaction (PCR) and Sanger sequencing were used to detect inhibitor of nuclear factor kappa-B kinase subunit gamma (IKBKG) mutation in the IP patient. We used the nuclear factor kappa B (NF-κB) reporter gene to assess activation of NF-κB, after transfecting an empty vector, wild-type, or mutant NF-κB essential modulator (NEMO) plasmid into IKBKG-deficient HEK293T cells, respectively. Furthermore, we performed immunoprecipitation and immunoblotting to describe the polyubiquitination of NEMO. Lastly, we detected the interactions between mutant NEMO and I kappa B kinase alpha (IKKα), I kappa B kinase beta (IKKβ), TNF receptor associated factor 6 (TRAF6), HOIL-1-interacting protein (HOIP), hemo-oxidized iron regulatory protein 2 ligase 1 (HOIL-1), and SHANK-associated RH domain interactor (SHARPIN).

RESULTS

A de novo nonsense mutation in IKBKG (c.924C > G; p.Tyr308*) was observed. The Tyr308* mutation inhibited activation of the NF-κB pathway by reducing K63-linked polyubiquitination and linear polyubiquitination. The mutant NEMO was not able to interact with TRAF6, HOIL-1, or SHARPIN.

CONCLUSIONS

We identified a novel nonsense IKBKG mutation (c.924C > G; p.Tyr308*) in an IP patient with syndromic tooth agenesis. This research enriches the mutation spectrum of the IKBKG gene.