No evidence for mutations in NLRP7, NLRP2 or KHDC3L in women with unexplained recurrent pregnancy loss or infertility.
OBJECTIVE
Are mutations in NLRP2/7 (NACHT, LRR and PYD domains-containing protein 2/7) or KHDC3L (KH Domain Containing 3 Like) associated with recurrent pregnancy loss (RPL) or infertility?


CONCLUSIONS
We found no evidence for mutations in NLRP2/7 or KHDC3L in unexplained RPL or infertility.


BACKGROUND
Mutations in NLRP7 and KHDC3L are known to cause biparental hydatidiform moles (BiHMs), a rare form of pregnancy loss. NLRP2, while not associated with the BiHM pathology, is known to cause recurrent Beckwith Weidemann Syndrome (BWS).


METHODS
Ninety-four patients with well characterized, unexplained infertility were recruited over a 9-year period from three IVF clinics in Sweden. Blood samples from 24 patients with 3 or more consecutive miscarriages of unknown etiology were provided by the Recurrent Miscarriage Clinic at St Mary's Hospital, London, UK.


METHODS
Patients were recruited into both cohorts following extensive clinical studies. Genomic DNA was isolated from peripheral blood and subject to Sanger sequencing of NLRP2, NLRP7 and KHDC3L. Sequence electropherograms were analyzed by Sequencher v5.0 software and variants compared with those observed in the 1000 Genomes, single nucleotide polymorphism database (dbSNP) and HapMap databases. Functional effects of non-synonymous variants were predicted using Polyphen-2 and sorting intolerant from tolerant (SIFT).


RESULTS
No disease-causing mutations were identified in NLRP2, NLRP7 and KHDC3L in our cohorts of unexplained infertility and RPL.


CONCLUSIONS
Due to the limited patient size, it is difficult to conclude if the low frequency single nucleotide polymorphisms observed in the present study are causative of the phenotype. The design of the present study therefore is only capable of detecting highly penetrant mutations.


CONCLUSIONS
The present study supports the hypothesis that mutations in NLRP7 and KHDC3L are specific for the BiHM phenotype and do not play a role in other adverse reproductive outcomes. Furthermore, to date, mutations in NLRP2 have only been associated with the imprinting disorder BWS in offspring and there is no evidence for a role in molar pregnancies, RPL or unexplained infertility.


BACKGROUND
This study was funded by the following sources: Estonian Ministry of Education and Research (Grant SF0180044s09), Enterprise Estonia (Grant EU30020); Mentored Resident research project (Department of Obstetrics and Gynecology, Baylor College of Medicine); Imperial NIHR Biomedical Research Centre; Grant Number C06RR029965 from the National Center for Research Resources (NCCR; NIH). No competing interests declared.
Department of Obstetrics, Gynecology and Reproductive Sciences, University of California San Francisco, San Francisco, CA 94143, USA.
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Aghajanova
Interdepartmental Program in Translational Biology and Molecular Medicine, Baylor College of Medicine, Houston, TX 77030, USA Department of Obstetrics and Gynecology, One Baylor Plaza, Mailstop BCM610, Baylor College of Medicine, Houston, TX 77030, USA Jan and Dan Duncan Neurological Research Institute at Texas Children's Hospital, Houston, TX 77030, USA.
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Mahadevan
Competence Centre on Reproductive Medicine and Biology, Tartu 50410, Estonia.
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Altmäe
Department of Women's and Children's Health, Uppsala University, Uppsala 75105, Sweden.
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Stavreus-Evers
Department of Obstetrics and Gynaecology, St Mary's Campus, Imperial College London, London W2 1PG, UK.
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Regan
Paediatric and Developmental Pathology, Institute of Child Health/Great Ormond Street Hospital, London WC1N 1EH, UK.
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Sebire
Division of Women's Health, King's College London, Guy's Campus, London SE1 1UL, UK.
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Dixon
Trophoblastic Tumour Screening and Treatment Centre, Charing Cross Campus, Imperial College London, London W6 8RF, UK.
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Fisher
Interdepartmental Program in Translational Biology and Molecular Medicine, Baylor College of Medicine, Houston, TX 77030, USA Department of Obstetrics and Gynecology, One Baylor Plaza, Mailstop BCM610, Baylor College of Medicine, Houston, TX 77030, USA Jan and Dan Duncan Neurological Research Institute at Texas Children's Hospital, Houston, TX 77030, USA Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, TX 77030, USA iveyver@bcm.edu.
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Van den Veyver
D000026:Abortion, Habitual / Q000235:genetics*; D048868:Adaptor Proteins, Signal Transducing / Q000235:genetics*; D051017:Apoptosis Regulatory Proteins; D015331:Cohort Studies; D004252:DNA Mutational Analysis; D005260:Female; D006801:Humans; D007247:Infertility, Female / Q000235:genetics*; D009154:Mutation; D011247:Pregnancy; D011506:Proteins / Q000235:genetics*
D048868:Adaptor Proteins, Signal Transducing; D051017:Apoptosis Regulatory Proteins; C568062:KHDC3L protein, human; C495732:NLRP2 protein, human; C502448:NLRP7 protein, human; D011506:Proteins
KHDC3L; NLRP2; NLRP7; recurrent pregnancy loss; unexplained infertility