A case of Bloom syndrome manifesting with therapy-related myelodysplastic syndromes harboring a novel BLM gene variant

Bloom syndrome (BS) is an autosomal recessive genetic disorder caused by variants in the BLM gene. BS is characterized by distinct facial features, elongated limbs, and various dermatological complications including photosensitivity, poikiloderma, and telangiectatic erythema. The BLM gene encodes a RecQ helicase critical for genome maintenance, stability, and repair, and a deficiency in functional BLM protein leads to genomic instability and high predisposition to various types of cancers, particularly hematological and gastrointestinal malignancies. Here, we report a case of BS with a previously unreported variant in the BLM gene. The patient was a 34-year-old woman who presented with short stature, prominent facial features, and a history of malignancies, including lymphoma, breast cancer, and myelodysplastic syndromes (MDS). She was initially treated with azacitidine for MDS and showed transient improvement, but eventually died at age of 35 due to progression of MDS. Genetic screening revealed compound heterozygous variants in the BLM gene, with a recurrent variant previously reported in BS in one allele and a previously unreported variant in the other allele. Based on her characteristic clinical features and the presence of heterozygous variants in the BLM gene, she was diagnosed with BS harboring compound heterozygous BLM variants.

Mitochondrial DNA mutations can influence the post-implantation development of human mosaic embryos

Introduction: Several healthy euploid births have been reported following the transfer of mosaic embryos, including both euploid and aneuploid blastomeres. This has been attributed to a reduced number of aneuploid cells, as previously reported in mice, but remains poorly explored in humans. We hypothesized that mitochondrial function, one of the most critical factors for embryonic development, can influence human post-implantation embryonic development, including a decrease of aneuploid cells in mosaic embryos. Methods: To clarify the role of mitochondrial function, we biopsied multiple parts of each human embryo and observed the remaining embryos under in vitro culture as a model of post-implantation development (n = 27 embryos). Karyotyping, whole mitochondrial DNA (mtDNA) sequencing, and mtDNA copy number assays were performed on all pre- and post-culture samples. Results: The ratio of euploid embryos was significantly enhanced during in vitro culture, whereas the ratio of mosaic embryos was significantly reduced. Furthermore, post-culture euploid and culturable embryos had significantly few mtDNA mutations, although mtDNA copy numbers did not differ. Discussion: Our results indicate that aneuploid cells decrease in human embryos post-implantation, and mtDNA mutations might induce low mitochondrial function and influence the development of post-implantation embryos with not only aneuploidy but also euploidy. Analyzing the whole mtDNA mutation number may be a novel method for selecting a better mosaic embryo for transfer.

Comparative analyses define differences between BHD-associated renal tumour and sporadic chromophobe renal cell carcinoma

BACKGROUND

Birt-Hogg-Dubé (BHD) syndrome, caused by germline alteration of folliculin (FLCN) gene, develops hybrid oncocytic/chromophobe tumour (HOCT) and chromophobe renal cell carcinoma (ChRCC), whereas sporadic ChRCC does not harbor FLCN alteration. To date, molecular characteristics of these similar histological types of tumours have been incompletely elucidated.

METHODS

To elucidate renal tumourigenesis of BHD-associated renal tumours and sporadic renal tumours, we conducted whole genome sequencing (WGS) and RNA-sequencing (RNA-seq) of sixteen BHD-associated renal tumours from nine unrelated BHD patients, twenty-one sporadic ChRCCs and seven sporadic oncocytomas. We then compared somatic mutation profiles with FLCN variants and RNA expression profiles between BHD-associated renal tumours and sporadic renal tumours.

FINDINGS

RNA-seq analysis revealed that BHD-associated renal tumours and sporadic renal tumours have totally different expression profiles. Sporadic ChRCCs were clustered into two distinct clusters characterized by L1CAM and FOXI1 expressions, molecular markers for renal tubule subclasses. Increased mitochondrial DNA (mtDNA) copy number with fewer variants was observed in BHD-associated renal tumours compared to sporadic ChRCCs. Cell-of-origin analysis using WGS data demonstrated that BHD-associated renal tumours and sporadic ChRCCs may arise from different cells of origin and second hit FLCN alterations may occur in early third decade of life in BHD patients.

INTERPRETATION

These data further our understanding of renal tumourigenesis of these two different types of renal tumours with similar histology.

FUNDING

This study was supported by JSPS KAKENHI Grants, RIKEN internal grant, and the Intramural Research Program of the National Institutes of Health (NIH), National Cancer Institute (NCI), Center for Cancer Research.

Periodic paralysis due to cumulative effects of rare variants in SCN4A with small functional alterations

INTRODUCTION/AIMS

Mutations in the SCN4A gene encoding a voltage-gated sodium channel (Nav1.4) cause hyperkalemic periodic paralysis (HyperPP) and hypokalemic periodic paralysis (HypoPP). Typically, both HyperPP and HypoPP are considered as monogenic disorders caused by a missense mutation with a large functional effect. However, a few cases with atypical periodic paralysis phenotype have been caused by multiple mutations in ion-channel genes expressed in skeletal muscles. In this study we investigated the underlying pathogenic mechanisms in such cases.

METHODS

We clinically assessed two families: proband 1 with HyperPP and proband 2 with atypical periodic paralysis with hypokalemia. Genetic analyses were performed by next-generation sequencing and conventional Sanger sequencing, followed by electrophysiological analyses of the mutant Nav1.4 channels expressed in human embryonic kidney 293T (HEK293T) cells using the whole-cell patch-clamp technique.

RESULTS

In proband 1, K880del was identified in the SCN4A gene. In proband 2, K880del and a novel mutation, R1639H, were identified in the same allele of the SCN4A gene. Functional analyses revealed that the K880del in SCN4A has a weak functional effect on hNav1.4, increasing the excitability of the sarcolemma, which could represent a potential pathogenic factor. Although R1639H alone did not reveal functional changes strong enough to be pathogenic, Nav1.4 with both K880del and R1639H showed enhanced activation compared with K880del alone, indicating that R1639H may modify the hNav1.4 channel function.

DISCUSSION

A cumulative effect of variants with small functional alterations may be considered as the underpinning oligogenic pathogenic mechanisms for the unusual phenotype of periodic paralysis.

Changes in the number of babies born with Down syndrome in Japan

AIM

The number of babies born with Down syndrome has changed in recent years because of widespread availability of prenatal screening and advanced maternal age at delivery. In Japan, which has no public institutions that record data on babies born with chromosomal abnormalities (including Down syndrome), the accurate number remains unknown.

METHODS

The Japan Association of Obstetricians and Gynecologists Birth Defects Monitoring Program (hereafter the JAOG Program) is the only national survey of congenital anomalies in Japan. Using data from this survey and vital statistics, we investigated the changes in the number of babies born with Down syndrome in Japan from 2006 to 2019.

RESULTS

On performing linear regression analysis with the proportion of babies born with Down syndrome as the response variable, and the proportion of mothers giving birth at the age of 35 years or older as the explanatory variable, the regression coefficient was 0.0054 (p < 0.001). The proportion of mothers giving birth at the age of 35 years or older was useful for predicting the proportion of babies born with Down syndrome. This proportion has increased since 2006 but has remained almost unchanged since 2015. In 2019, it was 1/734.

CONCLUSIONS

This study revealed that the proportion of mothers giving birth at the age of 35 years or older strongly affected the proportion of babies born with Down syndrome. We assume that the proportion of babies is slightly affected by the increased number of pregnant women currently undergoing prenatal screening after the introduction of noninvasive prenatal genetic testing in 2013.

P–572 Purifying selection for aneuploidy cells in mosaicism embryo at post-implantation stage

Study question

Why low ratio mosaicism embryos develop to normal karyotype babies?

Summary answer

Our in vitro implantation assay clarified purifying selection for aneuploid cells in post implantation embryos.

What is known already

There are some reports about healthy live birth after transfer of mosaic embryos, which was reported for the first time from Italy in 2015. It is also reported that the abnormal cell is screened with the mouse in the embryo development, and only a normal cell contributes to the development. But it has not been examined in human.

Study design, size, duration

To clarify the change of aneuploid cells and mitochondrial activity in human embryo, we biopsied several parts from one blastocyst and examined karyotype. After in vitro implantation assay for biopsied embryos, we compared the karyotype of biopsy sample with that of cultured cell mass.

Participants/materials, setting, methods

Under the ethical review of Yokohama City University and informed consent with patients, we collected human surplus blastocysts those are donated after successful clinical treatment or discarded because of poor development grade. We biopsied multiple parts from one blastocyst and cultured the biopsied embryos, and extracted whole DNA from the biopsy samples and cultured embryos. Karyotyping by next generation sequencing were performed.

Main results and the role of chance

We analyzed 34 samples from 11 embryos, including 25 biopsy sample from 11 embryos and 9 cell mass from 7 cultured embryos. In the karyotype tracking results, even though biopsy sample analysis before the culture were uniformed aneuploid or chromosome mosaic, the developing embryo cell mass had normal karyotype. In one embryo as an example, among the three biopsied extra trophectoderm samples from that, two of them were mosaic, and one of them had uniformed chromosome 21 trisomy and chromosome 16 mosaic monosomy. But the embryo formed multiple cell mass in implantation assay. We examined karyotype of three cell mass, and the result from all were normal karyotype. We suggested that the chromosome aberration cells were screened in the human embryo development, and when the function was not carried out the embryo stopped the development.

Limitations, reasons for caution

Because of small number of samples available, we need more samples for a more accurate evaluation. Furthermore, we cannot evaluate the absolute mechanism that cells with chromosome aberration decreases.

Wider implications of the findings: Conventional PGT-A techniques are based on uniformed embryos developing hypothesized past time. As showed in some clinical reports, PGT-A can reduce of spontaneous abortion and chance of embryo transfer. Thinking about aneuploid cell purifying system in embryo development, effectiveness of PGT-A should be more questionable for infertility treatment.

Trial registration number

A200326004

Evaluation of the clinical performance of noninvasive prenatal testing at a Japanese laboratory

AIM

We aimed to evaluate the sensitivity, specificity, positive predictive value (PPV), and negative predictive value (NPV) of noninvasive prenatal testing (NIPT) in high-risk pregnant women.

METHODS

Pregnant women who underwent GeneTech NIPT, the most commonly used NIPT in Japan, between January 2015 and March 2019, at Japan NIPT Consortium medical sites were recruited for this study. The exclusion criteria were as follows: pregnant women with missing survey items, multiple pregnancy/vanishing twins, chromosomal abnormalities in the fetus other than the NIPT target disease, and nonreportable NIPT results. Sensitivity and specificity were calculated from the obtained data, and maternal age-specific PPV and NPV were estimated.

RESULTS

Of the 45 504 cases, 44 263 cases fulfilling the study criteria were included. The mean maternal age and gestational weeks at the time of procedure were 38.5 years and 13.1 weeks, respectively. Sensitivities were 99.78% (95% confidence interval [95% CI]: 98.78-99.96), 99.12% (95% CI: 96.83-99.76), and 100% (95% CI: 88.30-100) for trisomies 21, 18, and 13, respectively. Specificities were more than 99.9% for trisomies 21, 18, and 13, respectively. Maternal age-specific PPVs were more than 93%, 77%, and 43% at the age of 35 years for trisomies 21, 18, and 13, respectively.

CONCLUSION

The GeneTech NIPT data showed high sensitivity and specificity in the detection of fetal trisomies 21, 18, and 13 in high-risk pregnant women, and maternal age-specific PPVs were obtained. These results could provide more accurate and improved information regarding NIPT for genetic counseling in Japan.

Diverse Pathological Findings of Interstitial Lung Disease in a Patient with Dyskeratosis Congenita

A 42-year-old man with a history of surgery for tongue cancer was referred to our hospital due to an abnormal chest shadow. High-resolution computed tomography showed lower lobe reticulation. A physical examination revealed nail dystrophy, oral leukoplakia, and reticulated hypopigmentation. Lung biopsy revealed subpleural and perilobular fibrosis, suggestive of usual interstitial pneumonia. However, multiple pathological findings, including homogenous fibrosis and cell infiltration in the centrilobular region, which were compatible with nonspecific interstitial pneumonia, and bronchiolitis were also seen. Genetic testing showed a hemizygous missense mutation in the DKC1 gene, and the patient was diagnosed with dyskeratosis congenita. Although anti-fibrotic therapy was initiated, the patient's respiratory function has continued to decrease.

Retrospective details of false-positive and false-negative results in non-invasive prenatal testing for fetal trisomies 21, 18 and 13

OBJECTIVE

Maternal characteristics and neonatal outcomes associated with cell-free DNA (cfDNA) results were analysed retrospectively to assess the details of false-positive and false-negative results after initial blood sampling in non-invasive prenatal testing (NIPT).

STUDY DESIGN

A multicentre retrospective study was performed for women undergoing NIPT who received discordant cfDNA results between April 2013 and March 2018. The NIPT data obtained using massive parallel sequencing were studied in terms of maternal background, fetal fraction, z-scores, invasive procedure results and neonatal outcomes after birth.

RESULTS

Of the 56,545 women who participated in this study, 54 false-positive (0.095 %) and three false-negative (0.006 %) cases were found. Seven of the 54 false-positive cases (13.0 %) had vanishing twin on ultrasonography. Among the 18 false-positive cases of trisomy 18, confined placental mosaicism (CPM) was confirmed in three cases (16.7 %), while CPM was present in one of the three false-negative cases of trisomy 21.

CONCLUSION

These data suggest that the incidence of women with false-positive or false-negative results is relatively low, that such false results can often be explained, and that vanishing twin and CPM are potential causes of NIPT failure. Genetic counselling with regard to false results is important for clients prior to undergoing NIPT.

Attitudes toward and current status of disclosure of secondary findings from next-generation sequencing: a nation-wide survey of clinical genetics professionals in Japan

The management of secondary findings (SFs), which are beyond the intended purpose of the analysis, from clinical comprehensive genomic analysis using next generation sequencing (NGS) presents challenges. Policy statements regarding their clinical management have been announced in Japan and other countries. In Japan, however, the current status of and attitudes of clinical genetics professionals toward reporting them are unclear. We conducted a questionnaire survey of clinical genetics professionals at two time points (2013 and 2019) to determine the enforcement of the SF management policy in cases of comprehensive genetic analysis of intractable diseases and clinical cancer genome profiling testing. According to the survey findings, 40% and 70% of the respondents stated in the 2013 and 2019 surveys, respectively, that they had an SF policy in the field of intractable diseases, indicating that SF policy awareness in Japan has changed significantly in recent years. Furthermore, a total of 80% of respondents stated that their facility had established a policy for clinical cancer genome profiling testing in the 2019 survey. In both surveys, the policies included the selection criteria for genes to be disclosed and the procedure to return SFs, followed by recommendations and proposals regarding SFs in Japan and other countries. To create a better list of the genes to be disclosed, further examination is needed considering the characteristics of each analysis.

Qualitative investigation of the factors that generate ambivalent feelings in women who give birth after receiving negative results from non-invasive prenatal testing

Background

Women who receive negative results from non-invasive prenatal genetic testing (NIPT) may find that they later have mixed or ambivalent feelings, for example, feelings of accepting NIPT and regretting undergoing the test. This study aimed to investigate the factors generating ambivalent feelings among women who gave birth after having received negative results from NIPT.

Methods

A questionnaire was sent to women who received a negative NIPT result, and a contents analysis was conducted focusing on ambivalent expressions for those 1562 women who responded the questionnaire. The qualitative data gathered from the questionnaire were analyzed using the N-Vivo software package.

Results

Environmental factors, genetic counseling-related factors, and increased anticipatory anxiety, affected the feeling of ambivalence among pregnant women. Furthermore, pregnant women desired more information regarding the detailed prognosis for individuals with Down syndrome and living with them and/or termination, assuming the possibility that they were positive.

Conclusions

Three major interrelated factors affected the feeling of ambivalence in women. Highlighting and discussing such factors during genetic counseling may resolve some of these ambivalences, thereby enhancing the quality of decisions made by pregnant women.

Multicenter experience with large panel next-generation sequencing in patients with advanced solid cancers in Japan

Background

Application of next-generation DNA sequencing (NGS) has recently become increasingly common in the field of clinical oncology in several countries around the world. In Japan also, a system for applying NGS to routine clinical practice is gradually being established. During this process, we introduced in Japan the tumor-profiling MSK-IMPACT (Memorial Sloan Kettering-Integrated Mutation Profiling of Actionable Cancer Targets) assay.

Methods

We present here our initial experience with the use of MSK-IMPACT in 68 patients selected from two institutions in Japan between June 2016 and October 2017.

Results

MSK-IMPACT sequencing was successful and yielded results in specimens obtained from 64 of the 68 patients, representing an overall assay success rate of 94.1%. The top three cancer types tested were endometrial cancer (17.2%), pancreatic cancer (15.6%) and colorectal cancer (12.5%). Evaluation of the clinical actionability of the genetic alterations revealed that 25.0% of patients (n = 16) harbored at least one actionable alteration. However, enrolling the patients in a genomically matched clinical trial was difficult, mainly because most clinical trials are limited to tumors arising from a specific organ/site. One patient with microsatellite instability-high status, as determined by MSK-IMPACT, was treated with pembrolizumab and showed partial response.

Conclusions

Although tumor profiling by NGS and administration of genomically matched therapy is a promising strategy, because of its high cost, we need to consider how we can fit it into the Japanese medical system. Towards this end, we believe that it is important to share our initial experience for furthering precision medicine in Japan.

Classification of factors involved in nonreportable results of noninvasive prenatal testing (NIPT) and prediction of success rate of second NIPT

OBJECTIVE

To evaluate the reasons for nonreportable cell-free DNA (cfDNA) results in noninvasive prenatal testing (NIPT), we retrospectively studied maternal characteristics and other details associated with the results.

METHODS

A multicenter retrospective cohort study in pregnant women undergoing NIPT by massively parallel sequencing (MPS) with failed cfDNA tests was performed between April 2013 and March 2017. The women's data and MPS results were analyzed in terms of maternal characteristics, test performance, fetal fraction (FF), z scores, anticoagulation therapy, and other details of the nonreportable cases.

RESULTS

Overall, 110 (0.32%) of 34 626 pregnant women had nonreportable cfDNA test results after an initial blood sampling; 22 (20.0%) cases had a low FF (<4%), and 18 (16.4%) cases including those with a maternal malignancy, were found to have altered genomic profile. Approximately half of the cases with nonreportable results had borderline z score. Among the women with nonreportable results because of altered genomic profile, the success rate of retesting using a second blood sampling was relatively low (25.0%-33.3%). Thirteen (11.8%) of the women with nonreportable results had required hypodermic heparin injection.

CONCLUSIONS

The classification of nonreportable results using cfDNA analysis is important to provide women with precise information and to reduce anxiety during pregnancy.

Distribution of PAPP-A and total hCG between 11 and 13 weeks of gestation in Japanese pregnant women

Objectives: To establish the reference values for PAPP-A and total hCG between 11 and 13 weeks of gestation for the use of risk assessment of fetal aneuploidy in Japanese pregnant women.Methods: A multicenter prospective study was conducted. The subjects included only Japanese pregnant women with viable singleton who requested the first trimester combined (nuchal translucency and maternal serum marker) screening for fetal aneuploidy. Reference values of PAPP-A and total hCG in Japanese population were made and compared with them in Caucasian.Results: Overall 1,751 Japanese pregnant women were analyzed. Median vales of maternal serum concentration in Japanese pregnant women from 11 + 0-13 + 6 weeks' gestation were ranged from 3.01 to 9.51 mIU/mL for PAPP-A and from 70.2 to 58.3 IU/mL for total-hCG, respectively. Regression curve of median maternal serum PAPP-A and total-hCG concentration against gestational days are significantly higher in Japanese comparing with Caucasian. At most distant values, Japanese serum concentration indicated 1.45 MoM for total-hCG and 1.70 MoM for PAPP-A based on Caucasian regression curves.Conclusion: A modification of the equations by specific reference values is necessary for Japanese pregnant women at the risk assessment of chromosomal abnormalities using the first trimester maternal serum marker.

A case of a rare variant of Klinefelter syndrome, 47,XY,i(X)(q10)

Klinefelter syndrome is a condition in which a male patient has one Y chromosome and one or more extra X chromosomes. It is the most common sex chromosome disorder. Klinefelter syndrome is distinguished by many clinical features, such as infertility, high gonadotropin and low testosterone levels, increased height, and sparse body and facial hair. We report the case of a 32-year-old man who visited our hospital complaining of male infertility. Semen analysis showed azoospermia, and chromosomal analysis revealed a 47,XY,i(X)(q10) karyotype, which is a rare variant of Klinefelter syndrome. No spermatozoon was found on microdissection testicular sperm extraction, and the testis biopsy histology showed only Sertoli cells and hyalinised seminiferous tubules. 47,XY, i(X)(q10) has an additional isochromosome made of the long arm of the X chromosome, which shares some features of classical Klinefelter syndrome in many aspects, but patients are usually shorter than average height and have normal intelligence. In addition, to the best of our knowledge, no successful sperm extractions from 47,XY, i(X)(q10) patients were reported in the literature. The reports of patients who have undergone microdissection testicular sperm extraction are very rare. Further reports and studies of this chromosomal abnormality are needed.

An infertile patient with Y chromosome b1/b3 deletion presenting with congenital bilateral absence of the vas deferens with normal spermatogenesis

We report the case of a 46-year-old Chinese male patient who visited our clinic complaining of infertility. Semen analysis revealed azoospermia, and azoospermia factor c region partial deletion (b1/b3) was detected using Y chromosome microdeletion analysis. Testicular sperm extraction was performed after genetic counseling. The bilateral ductus deferens and a portion of the epididymis were absent, whereas the remaining epididymis was expanded. Motile intratesticular spermatozoa were successfully extracted from the seminiferous tubule. On histopathology, nearly complete spermatogenesis was confirmed in almost every seminiferous tubule. To our knowledge, this is the first case report of b1/b3 deletion with a congenital bilateral absence of the vas deferens and almost normal spermatogenesis.

Current status of non-invasive prenatal testing in Japan

AIM

The purpose of this study was to report the 3-year experience of a nationwide demonstration project to introduce non-invasive prenatal testing (NIPT) of maternal plasma for aneuploidy, and review the current status of NIPT in Japan.

METHODS

Tests were conducted to detect aneuploidy in high-risk pregnant women, and adequate genetic counseling was provided. The clinical data, test results, and pregnancy outcomes were recorded. We discuss the problems of NIPT on the basis of published reports and meta-analyses.

RESULTS

From April 2013 to March 2016, 30 613 tests were conducted at 55 medical sites participating in a multicenter clinical study. Among the 30 613 women tested, 554 were positive (1.81%) and 30 021 were negative (98.1%) for aneuploidy. Of the 289, 128, and 44 women who tested positive for trisomies 21, 18, and 13, respectively, and underwent definitive testing, 279 (96.5%), 106 (82.8%), and 28 (63.6%) were determined to have a true-positive result. For the 13 481 women with negative result and whose progress could be traced, two had a false-negative result (0.02%). The tests were performed on the condition that a standard level of genetic counseling be provided at hospitals.

CONCLUSION

Here, we report on the 3-year nationwide experience with NIPT in Japan. It is important to establish a genetic counseling system to enable women to make informed decisions regarding prenatal testing. Moreover, a welfare system is warranted to support women who decide to give birth to and raise children with chromosomal diseases.

Peran Mutasi Gen CRELD1 pada Defek Septum Ventrikel dan Hubungannya dengan Manifestasi Klinis

Latar belakang. Defek septum ventrikel (DSV) merupakan salah satu jenis penyakit jantung bawaan (PJB) yang paling sering ditemukan. Etiologi DSV berhubungan dengan faktor genetik, nongenetik, atau interaksi antara faktor genetik dan nongenetik. Gen CRELD1 adalah suatu gen yang terletak pada kromosom 3p25. Mutasi gen CRELD1 akan menyebabkan gangguan pada pembentukan septum interventrikular.Tujuan. Mengetahui peran mutasi gen CRELD1 pada DSV dan hubungannya dengan manifestasi klinis.Metode. Subjek penelitian adalah 61 pasien DSV dan 110 pasien kontrol tanpa PJB yang memenuhi kriteria inklusi. Deteksi mutasi gen CRELD1 dilakukan dengan pemeriksaan sekuensing terhadap isolasi DNA.Hasil. Ditemukan satu anak dengan mutasi CRELD1, mutasi yang terjadi adalah missense mutations dan tempat mutasi terletak pada ekson 10 c.1136T>C (p. Met379Thr). Mutasi tersebut tidak ditemukan pada kontrol. Mutasi gen CRELD1 terjadi pada anak dengan DSV inlet besar dan disertai hipertensi pulmonal. Ditemukan empat tempat mutasi SNPs, tiga di antaranya telah dilaporkan ke gene Bank sebagai SNPs, dan satu tempat mutasi belum pernah dilaporkan.Kesimpulan. Didapatkan mutasi gen CRELD1 pada DSV inlet besar dan hipertensi pulmonal, sehingga perlu segera dilakukan penutupan defek ventrikel. Maka adanya mutasi gen CRELD1 dapat digunakan sebagai deteksi dini dan tata laksana yang lebih baik terhadap DSV.

A survey on awareness of genetic counseling for non-invasive prenatal testing: the first year experience in Japan

The purpose of this study is to summarize the results from a survey on awareness of genetic counseling for pregnant women who wish to receive non-invasive prenatal testing (NIPT) in Japan. As a component of a clinical study by the Japan NIPT Consortium, genetic counseling was conducted for women who wished to receive NIPT, and a questionnaire concerning both NIPT and genetic counseling was given twice: once after pre-test counseling and again when test results were reported. The responses of 7292 women were analyzed. They expressed high satisfaction with the genetic counseling system of the NIPT Consortium (94%). The number of respondents who indicated that genetic counseling is necessary for NIPT increased over time. Furthermore, they highly valued genetic counseling provided by skilled clinicians, such as clinical geneticists or genetic counselors. The vast majority (90%) responded that there was sufficient opportunity to consider the test ahead of time. Meanwhile, women who received positive test results had a poor opinion and expressed a low-degree satisfaction. We confirmed that the pre-test genetic counseling that we conducted creates an opportunity for pregnant women to sufficiently consider prenatal testing, promotes its understanding and has possibilities to effectively facilitate informed decision making after adequate consideration. A more careful and thorough approach is considered to be necessary for women who received positive test results.

[Case of azoospermia patient with a chromosomal abnormality considered a ring Y chromosome]

A 43-year-old man came to our clinic complaining of infertility and semen analysis showed azoospermia. Analysis of chromosomes showed a mosaic 45, XO/46, X, ＋mar1/46, X, ＋mar2 karyotype, and the marker chromosomes were considered to be two kinds of ring Y chromosomes. Y chromosome microdeletion analysis showed partial deletion of Azoospermic Factor (AZF) a, and complete deletion of AZFb and AZFc. The patient gave up having a child because these results indicated that no sperm would be collected even if Testicular Sperm Extraction (TESE) were performed.

Whole-exome sequencing identified a homozygous FNBP4 mutation in a family with a condition similar to microphthalmia with limb anomalies

Microphthalmia with limb anomalies (MLA), also known as Waardenburg anophthalmia syndrome or ophthalmoacromelic syndrome, is a rare autosomal recessive disorder. Recently, we and others successfully identified SMOC1 as the causative gene for MLA. However, there are several MLA families without SMOC1 abnormality, suggesting locus heterogeneity in MLA. We aimed to identify a pathogenic mutation in one Lebanese family having an MLA-like condition without SMOC1 mutation by whole-exome sequencing (WES) combined with homozygosity mapping. A c.683C>T (p.Thr228Met) in FNBP4 was found as a primary candidate, drawing the attention that FNBP4 and SMOC1 may potentially modulate BMP signaling.

Rapid detection of a mutation causing X-linked leucoencephalopathy by exome sequencing

BACKGROUND

Conventional PCR-based direct sequencing of candidate genes for a family with X-linked leucoencephalopathy with unknown aetiology failed to identify any causative mutations.

OBJECTIVE

To carry out exome sequencing of entire transcripts of the whole X chromosome to investigate a family with X linked leucoencephalopathy.

METHODS AND RESULTS

Next-generation sequencing of all the transcripts of the X chromosome, after liquid-based genome partitioning, was performed on one of the two affected male subjects (the proband) and an unaffected male subject (his brother). A nonsense mutation in MCT8 (c.1102A→T (p.R368X)) was identified in the proband. Subsequent PCR-based direct sequencing of other family members confirmed the presence of this mutation, hemizygous in the other affected brother and heterozygous in the proband's mother and maternal grandmother. MCT8 mutations usually cause abnormal thyroid function in addition to neurological abnormalities, but this proband had normal thyroid function.

CONCLUSION

Single-lane exome next-generation sequencing is sufficient to fully analyse all the transcripts of the X chromosome. This method is particularly suitable for mutation screening of X-linked recessive disorders and can avoid biases in candidate gene choice.

SMOC1 is essential for ocular and limb development in humans and mice

Microphthalmia with limb anomalies (MLA) is a rare autosomal-recessive disorder, presenting with anophthalmia or microphthalmia and hand and/or foot malformation. We mapped the MLA locus to 14q24 and successfully identified three homozygous (one nonsense and two splice site) mutations in the SPARC (secreted protein acidic and rich in cysteine)-related modular calcium binding 1 (SMOC1) in three families. Smoc1 is expressed in the developing optic stalk, ventral optic cup, and limbs of mouse embryos. Smoc1 null mice recapitulated MLA phenotypes, including aplasia or hypoplasia of optic nerves, hypoplastic fibula and bowed tibia, and syndactyly in limbs. A thinned and irregular ganglion cell layer and atrophy of the anteroventral part of the retina were also observed. Soft tissue syndactyly, resulting from inhibited apoptosis, was related to disturbed expression of genes involved in BMP signaling in the interdigital mesenchyme. Our findings indicate that SMOC1/Smoc1 is essential for ocular and limb development in both humans and mice.

Disrupted SOX10 regulation of GJC2 transcription causes Pelizaeus-Merzbacher-like disease

Mutations in the gap junction protein gamma-2 gene, GJC2, cause a central hypomyelinating disorder; Pelizaeus-Merzbacher-like disease (PMLD; MIM311601). Using a homozygosity mapping and positional candidate gene approach, we identified a homozygous mutation (c.-167A>G) within the GJC2 promoter at a potent SOX10 binding site in a patient with mild PMLD. Functionally, this mutation completely abolished the SOX10 binding and attenuated GJC2 promoter activity. These findings suggest not only that the SOX10-to-GJC2 transcriptional dysregulation is a cause of PMLD, but also that GJC2 may be in part responsible for the central hypomyelination caused by SOX10 mutations.

A locus for ophthalmo-acromelic syndrome mapped to 10p11.23

Ophthalmo-acromelic syndrome (OAS, OMIM %206920) is a rare autosomal recessive disease, presenting with clinical anophthalmia and limb anomalies. We recruited three OAS families including a Japanese family with two affected patients and two consanguineous Lebanese families each having an affected. Homozygosity mapping was performed using the 50K SNP chip and additional informative markers. A locus for OAS was mapped to the 422-kb region at 10q11.23, based on the results from the two consanguineous families as well as the consistent data from the Japanese non-consanguineous family. The 422-kb region only contained one gene, MPP7. Although we could not detect any pathological mutations in OAS families analyzed, MPP7 could remain a candidate as aberrant changes might exist beyond our mutation detection methods. Further families are needed to confirm this candidate locus.

A -16C>T substitution in the 5' UTR of the puratrophin-1 gene is prevalent in autosomal dominant cerebellar ataxia in Nagano

The molecular bases of autosomal dominant cerebellar ataxia (ADCA) have been increasingly elucidated, but 17-50% of ADCA families still remain genetically undefined in Japan. In this study we investigated 67 genetically undefined ADCA families from the Nagano prefecture, and found that 63 patients from 51 families possessed the -16C>T change in the puratrophin-1 gene, which was recently found to be pathogenic for 16q22-linked ADCA. Most patients shared a common haplotype around the puratrophin-1 gene. All patients with the -16C>T change had pure cerebellar ataxia with middle-aged or later onset. Only one patient in a large, -16C>T positive family did not have this change, but still shared a narrowed haplotype with, and was clinically indistinguishable from, the other affected family members. In Nagano, 16q22-linked ADCA appears to be much more prevalent than either SCA6 or dentatorubral-pallidoluysian atrophy (DRPLA), and may explain the high frequency of spinocerebellar ataxia.

Complete hydatidiform mole and normal live birth following intracytoplasmic sperm injection

A twin pregnancy with complete hydatidiform mole (HM) and preterm birth of a normal female infant after intracytoplasmic sperm injection (ICSI) conception was experienced. ICSI due to severe oligozoospermia was performed on three ova, and three embryos with confirmed two proneclei (2PN) were subsequently transferred to the uterus. At 7 weeks of gestation, molar pregnancy as well as a viable fetus was recognized. At 33 weeks, the pregnancy was terminated due to preterm labor. Dichorionic pregnancy consisting of a normal fetus and placenta in one chorionic membrane and complete HM in the other was recognized. Cytomolecular analysis indicated that the complete HM genome was derived from duplication of a single sperm, and a normal neonate was from biparental genomes. It should be noted that ICSI can avoid incomplete HM (mostly triploid) due to multi-sperm fertilization but might not be able to avoid complete HM (paternal diploid) although such a risk is very low. This is the second report of this condition and is accompanied by the first well-described molecular analysis.