Novel biallelic mutations in PADI6 in patients with early embryonic arrest.

Peptidyl arginine deiminase, type VI (PADI6) is a member of the subcortical maternal complex (SCMC), which plays vital roles in mammalian embryogenesis. Most mutations in SCMC members have been reported to cause human embryonic arrest, and a total of 15 mutations in PADI6 have been shown to be responsible for early embryonic arrest according to previous studies. However, the genetic factors behind this phenotype remain to be understood in further detail. Here, we identified 13 novel mutations and 4 previously reported mutations of PADI6 in 14 patients who were diagnosed with abnormal embryonic development caused by early arrest, embryonic fragmentation, and recurrent implantation failure. Most of the mutations were predicted by in silico analysis to be deleterious or damaging to the function of PADI6. In addition, the total and East Asian population frequencies of the mutations were low or absent in the gnomAD database. Our study expands the mutational spectrum in PADI6 and will provide precise targets for genetic counseling in the future.

Next-generation sequencing analysis of each blastomere in good-quality embryos: insights into the origins and mechanisms of embryonic aneuploidy in cleavage-stage embryos.

PURPOSE: To explore the whole-chromosome status, origins, and mechanisms of chromosomal abnormalities in good-quality cleavage embryos using multiple annealing and looping-based amplification cycle (MALBAC) sequencing. METHODS: The embryos studied came from7 patients (maternal aged 26-35) who had healthy birth from the same IVF cycles. These 21 frozen day 3 good-quality embryos were thawed and disaggregated into individual blastomere. Each blastomere was collected and analyzed by MALBAC sequencing. RESULTS: Conclusive results were obtained from a high percentage of blastomeres (95.3%). A total of 46.6% of blastomeres were diploid, 53.4% were abnormal, and 28.0% had complex aneuploidy. Out of 21 embryos, 3 (14.3%) were normal and 18 (85.7%) were mosaics, showing the occurrence of mitotic errors; aneuploidy was confirmed in all cells of 4 of the 18 embryos, which showed the coexistence of meiotic errors. Conclusive results were obtained from all blastomeres of 15 embryos (71.4%, 15/21), which enabled us to reconstruct the cell lineage on the basis of the chromosomal content of the blastomeres in each division. There were 9 mitotic errors (8.7%, 9/103): nondisjunction accounted for 88.9% (8/9), and endoreplication accounted for 11.1% (1/9). CONCLUSIONS: In good-quality embryos, there was a high rate and diverse array of chromosomal abnormalities. Morphological evaluation does not appear to assist in the reduction in meiotic errors from parental origins. Mitotic errors were common, and nondisjunction was found to be the main mechanism causing malsegregation during the cleavage divisions.

[Analysis of chromosomal mosaicism in good quality cleavage embryos].

OBJECTIVE: To apply single cell sequencing based on multiple annealing and looping amplification cycles (MALBAC) for the determination of the rate and type of mosaicisms of high-quality embryos at cleavage stage. METHODS: After thawing and removing of zona pellucida by enzymatic digestion, blastomeres were collected the high-quality embryos donated by couples whom had given birth to healthy offspring by intracytoplasmic sperm injection and embryo transfer. The whole genome of single cell was amplified and subjected to next generation sequencing. RESULTS: From a total of 23 embryos, 184 blastomeres were collected. 175 (95.1%) of the blastomeres were successfully sequenced, of which 100 (57.1%) were found to harbor chromosomal aneuploidies. Among the 23 embryos, 3 (13.0%) were diploid, 20 (87.0%) were mosaicisms, which included 5 (21.7%) aneuploid mosaicisms, 7 (30.4%) diploid-aneuploid mosaicisms, 5 (21.7%) abnormal mosaicisms, and 3 (13.0%) irregular segregations. CONCLUSION: There is a high rate of chromosomal mosaicisms in high-quality cleavage embryos. Mosaicisms of complex chromosomal abnormality or with high proportion of abnormal cells may be an important factor affecting the potential of embryonic development.

[Clinical and genetic features of 45,X maleness: A case report and review of the literature].

OBJECTIVE: To explore the relationship between the clinical and genetic features of a short-statured azoospermia male with the karyotype of 45,X. METHODS: Using GTG-banded chromosome analysis, we performed karyotyping for a 150 cm-high infertile male with azoospermia and investigated the presence and location of the genes on the Y chromosome by FISH and PCR. RESULTS: GTG-banded chromosome analysis showed the karyotype of the patient to be 45,X,add(14)(p11). The results of PCR manifested the deletion of AZFa, AZFb, AZFc, and AZFd in the SRY gene. FISH revealed the translocation of the short arm of the Y chromosome to that of chromosome 14 and deletion of most proportions of its long arm, with the disruption site close to the centromere region. The karyotype of the patient was 45,X,der(Y)t(Y;14)(q11;q11.2), 14.ish (SRY+, CEP Y+ , DYZ1－). CONCLUSIONS: The karyotype of the patient was unbalanced Y/14 translocation. The SRY gene is the key to maleness. The deletion of AZFa－ d induces spermatogenic disturbance, and the deletion of the q arm of the Y chromosome may be related with short stature.

Glycerol-3-phosphate acyltransferase 4 gene is involved in mouse spermatogenesis.

Glycerol-3-phosphate acyltransferase (GPAT) catalyzes the first committed step of de novo triacylglycerol synthesis by converting glycerol-3-phosphate to lysophosphatidic acid (LPA). LPA is a mitogen that mediates multiple cellular processes including cell proliferation. Four GPAT isoforms have been cloned to date. GPAT4 is strongly expressed in the mouse testis. Reverse transcription- polymerase chain reaction (PCR), real-time PCR, and in situ hybridization (ISH) were used to analyze the GPAT4 expression and to localize the expressing cell types in the mouse testis during postnatal development. GPAT4 cDNA was inserted into pcDNA4/His to construct a recombinant vector, which was transfected into a mouse spermatogonial cell line (GC-1spg). GPAT4 was first expressed in mice at 2 weeks postnatally. Expression was abundant from the third week, plateaued at week 5-6 and then maintained at a high level in the adult. ISH revealed that GPAT4 gene was expressed abundantly in spermatocytes and around spermatids during meiosis but not in elongated spermatids during later spermiogenesis. GC-1spg cells showed a marked increase in proliferation after transfection with GPAT4; cell cycle analysis showed a decrease in the percentage of cells in the G0/G1 phase and an increase in the S phase. Thus, GPAT4 might play an important role in spermatogenesis, especially in mid-meiosis.

[Mutation of KLHL-10 in idiopathic infertile males with azoospermia, oligospermia or asthenospermia].

OBJECTIVE: To investigate the relationship of the mutation of the spermatogenesis-associated gene KLHL-10 with azoospermia, oligospermia and asthenospermia. METHODS: Genomic DNA was extracted from the peripheral blood samples of 325 patients with idiopathic azoospermia (n = 11), oligozoospermia (n = 196) or asthenospermia (n = 118) and 100 fertile male controls. KLHL-10 mutations were detected for all the DNA specimens by PCR, DHPLC and sequencing techniques. RESULTS: A novel heterozygous mutation (C88 --> A) was identified in exon 1 from 1 oligospermia patient and 3 fertile male controls and another one (C424 --> A) confirmed in exon 2 from 4 fertile controls, 3 oligospermia patients and 1 asthenospermia man. Both of the mutations were synonymous, but neither missense mutation nor microdeletion of the KLHL-10 gene was found. CONCLUSION: The KLHL-10 gene is not a major contributor to azoospermia, oligospermia or asthenospermia in Chinese population. The value of this gene in the diagnosis of male infertility remains to be further investigated.

A newly discovered mutation in PICK1 in a human with globozoospermia.

Globozoospermia is a human infertility syndrome caused by spermatogenesis defects (OMIM 102530). Acrosome plays an important role at the site of sperm-zonapellucida binding during the fertilization process. Thus, malformation of the acrosome is the most prominent feature seen in globozoospermia. Disruption of several mouse genes, including Gopc (Golgi-associated PDZ and coiled-coil motif containing protein), Hrb (HIV-1 Rev binding protein), Csnk2a2 (casein kinase 2, alpha prime polypeptide) and Pick1 (protein interacting with C kinase 1), results in a phenotype similar to globozoospermia in humans, which suggests their potential role in the disease. However, no mutations with a clear link to globozoospermia have been identified in these genes in humans. In this study, we screened the candidate genes mentioned above in three globozoospermia type I patients and discovered a homozygous missense mutation (G198A) in exon 13 of the PICK1 gene in a Chinese family. The family member affected by this homozygous missense mutation showed a complete lack of acrosome. Using the candidate gene screening strategy, our study is the first to identify an autosomal recessive genetic mutation in PICK1 that was responsible for globozoospermia in humans.