First trimester diagnosis of partial mole

Background Partial mole is one of the two distinctive subtypes of hydatidiform mole. It is usually paternally derived triploid conceptions in which embryonal development occurs in association with trophoblastic hyperplasia. The definite diagnosis is confirmed by pathological and cytogenetic studies. Ultrasound might be helpful to diagnose partial mole in the first trimester.Case A 25-year-old woman, gravida 2, para 0-0-1-0, was initially seen for antenatal care at 6 weeks pregnant. Ultrasound was undertaken at 13 weeks pregnancy due to her first fetal anomaly, which demonstrated partial mole and embryonic death. The serum hCG was 190,900 mIU/ml. Suction curettage was performed without complication. Histopathological study confirmed partial mole and cytogenetic study of the placenta revealed an uncommon karyotype, mosaicism of triploid (69,XXX/69,XXY). Serum hCG was declined and negative at 8 weeks. The patient was well and serum hCG remained normal throughout 6 months of follow-up.Conclusion Although the majority of partial mole pregnancies cannot be detected by routine first trimester ultrasound examination, first trimester ultrasound can be helpful in some cases, such as this one. If partial mole is sonographically suspected, it should be confirmed with histopathology and cytogenetic studies. The management is similar to complete mole including prompt evacuation and careful monitoring of hCG.     

Methylation analysis in tongue tissue of BWS patients identifies the (EPI)genetic cause in 3 patients with normal methylation levels in blood

The Beckwith–Wiedemann syndrome is caused by disturbed imprinting of genes at 11p15.5. Routine diagnostic testing for Beckwith–Wiedemann syndrome (BWS) includes methylation analysis of the imprinting centers ICR1 and ICR2 in DNA extracted from lymphocytes. In approximately 15% of BWS patients the diagnosis cannot be molecularly confirmed. In this study we determined the methylation status in resected tongue tissue of 11 BWS patients and compared this to the genetic defects found by routine diagnostic screening of blood lymphocytes. In all three patients with normal methylation levels in blood, aberrant methylation patterns were found in tongue tissue. In two patients a UPD was detected and the third case had hypermethylation of ICR1. This result shows that tissue specific mosaic (epi)genetic changes, not present in blood, is the underlying defect in at least a subset of BWS patients without a molecular diagnosis after standard genetic testing.     

Clinical outcomes after the transfer of blastocysts characterized as mosaic by high resolution Next Generation Sequencing- further insights

ObjectiveTo determine the pregnancy outcome potential of euploid, mosaic and aneuploid embryos.DesignRetrospective study.SettingReference genetics laboratories.Patient(s)2654 PGT-A cycles with euploid characterized embryo transfers, 253 PGT-A cycles with transfer of embryos characterized as mosaic, and 10 PGT-A cycles with fully abnormal embryo transfers.Intervention(s)Blastocysts were assessed by trophectoderm (TE) biopsy followed by PGT-A via array CGH or NGS.Main outcome measure(s)Implantation, miscarriage, ongoing implantation rates (OIR), and karyotype if available, were compared between different embryo groups, and between the two PGT-A techniques.ResultsThe Ongoing Pregnancy Rate (OPR)/transfer was significantly higher for NGS-classified euploid embryos (85%) than for aCGH ones (71%) (p < 0.001), but the OPR/cycle was similar (63% vs 59%). NGS-classified mosaic embryos resulted in 37% OPR/cycle (p < 0.001 compared to euploid). Mosaic aneuploid embryos with <40% abnormal cells in the TE sample had an OIR of 50% compared to 27% for mosaics with 40–80% abnormal cells in the TE, and 9% for complex mosaic embryos. All the karyotyped ongoing pregnancies (n = 29) were euploid. Transfers of embryos classified as aneuploid via aCGH (n = 10) led to one chromosomally abnormal pregnancy.Conclusion(s)NGS-classified euploid embryos yielded higher OIRs but similar OPRs/cycle compared to aCGH. NGS-classified mosaic embryos had reduced potential to reach term, compared to euploid embryos. If they did reach term, those with karyotype results available were euploid. Embryos carrying uniform aneuploidies affecting entire chromosomes were mostly unable to implant after transfer, and the one that implanted ended up in a chromosomally abnormal live birth.     

Hypomelanosis of Ito with Multiple Congenital Anomalies

Hypomelanosis of Ito (HI) is a neurocutaneous disorder, also known as incontinentia pigmenti achromians. HI has been associated with chromosomal abnormalities, especially mosaicism. Herein, we report a case of HI with multiple congenital anomalies. A 2-month-old girl presented with multiple linear and whorling hypopigmentation on the face, trunk, and both extremities and patch alopecia on the scalp. Moreover, she had conical teeth, aniridia of the both eyes, and multiple musculoskeletal problems, including syndactyly and coccyx deviation. Cytogenetic analysis on peripheral blood was normal 46, XX, and no mutation was found in IKBKG gene test.     

一例 TSC2基因低比例突变嵌合体基因学分析

目的对一例临床表现不典型的结节性硬化症（TSC）患者进行基因突变分析以明确诊断。方法收集一例临床上拟诊TSC的患者及其父母的外周血，通过全外显子组测序技术对先证者 TSC1和 TSC2基因的全部外显子及其侧翼序列进行测序，确定候选致病突变位点，同时对先证者及其父母的外周血DNA进行Sanger测序验证，并用液滴数字PCR技术确定先证者体细胞中该突变嵌合比例。 结果先证者的 TSC2基因第11号外显子存在c.1096G>T（p.E366*）杂合无义突变，为微小突变峰，突变比例未高于其突变阈值，不排除嵌合体的可能。液滴数字PCR结果提示，先证者为c.1096G>T点突变嵌合体，嵌合比例为14%。 结论先证者 TSC2基因发生体细胞镶嵌突变，c.1096G>T可能是该TSC患者的致病原因。液滴数字PCR有助于体细胞镶嵌突变嵌合体的确诊。     

Trophectoderm biopsy protocols may impact the rate of mosaic blastocysts in cycles with pre-implantation genetic testing for aneuploidy

PurposeThis study aimed to analyze the impact of different biopsy protocols on the rate of mosaic blastocysts.MethodsThis is a retrospective cohort study which included 115 cycles with pre-implantation genetic testing for aneuploidy (PGT-A). Two groups were allocated based on the biopsy protocols: method 1 group, the zona pellucida (ZP) was drilled on day 3 embryos followed by trophectoderm (TE) biopsy; and method 2 group, the ZP was opened on day 5 or 6 blastocysts followed by TE biopsy. All biopsy samples were assessed using next-generation sequencing (NGS) at a single reference laboratory. The euploid, aneuploid, and mosaic blastocyst rates and clinical outcomes were compared.ResultsThe mosaicism rate in the method 1 group was 19.58%, significantly higher than the method 2 group (8.12%; P < 0.05). No statistically significant difference was observed in euploid, aneuploid blastocyst rates, and clinical pregnancy rates between the two groups. Logistic regression analysis indicated that the biopsy protocols were independently associated with the mosaicism rates among all the variables.ConclusionsThe present study showed that different biopsy protocols may have an impact on the mosaic blastocyst rate. ZP opening on day 3 combined with TE biopsy might increase the incidence of mosaic blastocysts.     

三个Rb基因突变嵌合体家系分子遗传学分析

目的：遗传型RB是一种单基因疾病，由定位在13q14的Rb基因突变所致。大多数遗传性RB表现出典型的孟德尔常染色体显性遗传特征。作者分析三个遗传性RB家系RB外显不全及表型传递规律变异的原因。 方法：RELPs和VNTRs作单体型分析，SSCP及直接DNA序列分析检测Rb基因点突变。 结果：Rb基因突充嵌合体是造成某些Rb基因突变携带者不发病以及家庭成员中RB表型遗传不符合孟德尔规则的重要原因之一。结论：直接检测致病性的Rb基因突变才能准确判断携带者，估计患病风险。 （中华眼底病杂志，1996，12：37-40）     

A dispermic chimera with mixed field blood group B and mosaic 46,XY/47,XYY karyotype

Chimerism in humans is a rare phenomenon often initially identified in the resolution of an ABO blood type discrepancy. We report a dispermic chimera who presented with mixed field in his B antigen typing that might have been mistaken for the B3 subtype. The propositus is a healthy Korean male blood donor. Neither his clinical history nor initial molecular investigation of his ABO gene explained his mixed field agglutination with murine anti-B. Chimerism was suspected, and 9 short tandem repeat (STR) loci were analyzed on DNA extracted from blood, buccal swabs, and hair from this donor and on DNA isolated from peripheral blood lymphocytes from his parents. The propositus' red blood cells demonstrated mixed field agglutination with anti-B. Exon 6 and 7 and flanking intronic regions of his ABO gene were sequenced and revealed an O01/O02 genotype. B allele haplotype-specific PCR, along with exon 6 and 7 cloning and sequencing demonstrated a third ABO allele, B101. Four STR loci demonstrated a pattern consistent with a double paternal chromosome contribution in the propositus, thus confirming chimerism. His karyotype revealed a mosaic pattern: 32/50 metaphases were 46,XY and 18/50 metaphases demonstrated 47,XYY.