Somatic variants in autosomal dominant genes are a rare cause of sporadic Alzheimer's disease

Introduction

A minority of patients with sporadic early-onset Alzheimer's disease (AD) exhibit de novo germ line mutations in the autosomal dominant genes such as APP, PSEN1, or PSEN2. We hypothesized that negatively screened patients may harbor somatic variants in these genes.

CLONAL ORIGIN OF γ-GLUTAMYL TRANSPEPTIDASE-POSITIVE HEPATIC LESIONS INDUCED BY INITIATION-PROMOTION IN ORNITHINE CARBAMOYLTRANSFERASE MOSAIC MICE

Since the deficiency of ornithine carbamoyl-transferase (OCT) is inherited as an X-linked dominant trait in sparse-fur with abnormal skin and hair (Spf-ash) mice, the livers of heterozygous Spf-ash females show mosaicism in regard to OCT. We induced enzyme-altered foci and nodules, presumptive preneoplastic lesions for hepatocellular carcinomas, in the livers of OCT mosaic mice (Spf-ash × C3H F1), and investigated the clonality of the lesions. Simultaneous histochemical staining for OCT and γ -glutamyl transpeptidase (GGT) demonstrated that all GGT-positive lesions (ranging in size from 3 cells to a few millimeters in diameter) were either positive or negative for OCT, and no mosaic lesions were detectable. The results indicate that individual enzyme-altered hepatocytic lesions are the result of clonal proliferation.     

产前诊断中胎儿性染色体嵌合体的发生率及其妊娠结局

目的：分析妊娠中期产前诊断中胎儿性染色体嵌合体的发生率及其妊娠结局。方法：回顾性分析我院2016年1月-2017年12月10 341例羊水染色体核型分析的结果,进而分析35例性染色体嵌合体的临床结局。结果：妊娠中期通过羊水染色体核型分析的产前诊断病例中,性染色体嵌合体发生率为0.34%（35/10 341）,主要涉及3种嵌合类型：45,X/46,XX嵌合（17例）、45,X/46,XY嵌合（8例）和45,X与其他异常核型嵌合（10例）。在35例性染色体嵌合体中,产前诊断指征涉及无创提示性染色体数目异常、唐筛高风险、B型超声（B超）指标异常以及高龄,其终止妊娠率分别为86%（12/14）、83%（5/6）、75%（6/8）和29%（2/7）。结论：当产前诊断检出胎儿性染色体嵌合体时,建议结合染色体微阵列技术、荧光原位杂交检测技术、胎儿脐血核型检测以及B超等结果进行综合分析,从而为产前的遗传学咨询提供更加科学准确的信息和依据。     

Mosaic 15q13.3 deletion including CHRNA7 gene in monozygotic twins

Deletions in 15q13.3 belong to the most frequently identified recurrent CNVs, and lead to mental retardation, seizures and minor dysmorphism. We report on two monozygotic twin boys with a mosaic 1.5 Mb deletion in 15q13.3, including CHRNA7. The growth parameters were in the normal range for both twins. Both had language delay with hyperactivity, temper tantrums and poor social interaction but attended regular school. The percentage of abnormal cells was 40% on lymphocytes, and 25 and 35% on buccal smear in the first and second twins, respectively. The mosaicism for the 15q13.3 deletion can explain the milder phenotype observed in these two boys.     

Mosaic trisomy 18 at amniocentesis associated with a favorable fetal outcome in a pregnancy

ObjectiveWe present prenatal diagnosis of mosaic trisomy 18 by amniocentesis associated with a favorable fetal outcome in a pregnancy.Case reportA 42-year-old, gravida 4, para 2, woman underwent amniocentesis at 18 weeks of gestation because advanced maternal age. Amniocentesis revealed a karyotype of 47,XX,+18[6]/46,XX[17]. Simultaneous array comparative genomic hybridization (aCGH) on uncultured amniocytes showed the result of 45% mosaicism for trisomy 18. At 25 weeks of gestation, the woman underwent repeat amniocentesis which revealed a karyotype of 47,XX,+18[10]/46,XX[24]. Simultaneous aCGH on uncultured amniocytes showed the result of arr 18p11.32q23 (148,963–78,012,829) × 2.3 [GRCh (hg19)] with a log₂ ratio of 0.2–0.25 compatible with 30–38% mosaicism for trisomy 18. The parental karyotypes were normal. Prenatal ultrasound was unremarkable. Interphase fluorescence in situ hybridization (FISH) on uncultured amniocytes showed 27% (27/100 cells) mosaicism for trisomy 18. Quantitative fluorescent polymerase chain reaction (QF-PCR) on uncultured amniocytes excluded uniparental disomy (UPD) 18. Non-invasive prenatal testing (NIPT) analysis at 34 weeks of gestation revealed a significant gene dosage increase of chromosome 18 (29.95; normal control: ?3.0–3.0). At 39 weeks of gestation, a 2840-g phenotypically normal baby was delivered. The cord blood had a karyotype of 47,XX,+18[8]/46,XX[32]. The placenta was trisomy 18 of maternal origin. The umbilical cord had a karyotype of 47,XX,+18[2]/46,XX[38]. At age 1½ months, the peripheral blood had a karyotype of 47,XX,+18[5]/46,XX[35], and FISH analysis on buccal mucosal cells revealed 2% (2/102 cells) mosaicism for trisomy 18. When follow-up at age seven months, the neonate was phenotypically normal, and the peripheral blood had a karyotype of 47,XX,+18[1]/46,XX[39].ConclusionsMosaic trisomy 18 at amniocentesis without abnormal fetal ultrasound can be associated with a favorable outcome, and the abnormal trisomy 18 cell line may decrease progressively after birth.     

Complex malformation (Ruggieri–Happle) phenotype with “cutis tricolor” in a 10-year-old girl

The term cutis tricolor describes the combination of congenital hyper- and hypo-pigmented skin lesions in close proximity to each other in a background of normal complexion. It is currently regarded as a twin-spotting phenomenon and today is clear that not all cases of cutis tricolor represent one single entity. This phenomenon has been reported so far: (a) as an isolated skin manifestation; (b) as a part of a complex malformation syndrome (Ruggieri–Happle syndrome – RHS); (c) as a distinct phenotype [cutis tricolor parvimaculata]; (d) in association with other (e.g., vascular) skin disturbances. We report a novel case of cutis tricolor in a 10-year-old girl who had dysmorphic facial features [alike those seen in cases with syndromic (RHS) cutis tricolor], overall overgrowth [weight, length, and head circumference were >90th percentile; there was increased bone age], mild cognitive delay (current IQ = 55), behavioural disturbances, febrile seizures and (later) partial complex epilepsy (currently under good control), and skeletal defects [i.e., posterior scalloping of the lumbar vertebrae]. We discuss the main similarities and differences between the various phenotypes in the spectrum of cutis tricolor and with other conditions sharing features with the present case.     

染色体微阵列分析和低深度高通量全基因组测序技术在流产遗传学诊断中的应用

目的 探讨染色体微阵列分析(CMA)和低深度全基因组测序(CNV-seq)技术在流产遗传学病因诊断中的应用价值.方法 收集2018年5月至2019年10月在无锡妇幼保健院计划生育门诊就诊并确诊稽留流产患者的流产样本89例,对所有流产样本分别进行CMA和CNV-seq检测,比较两种方法整体检出率以及各种染色体异常情况的检...     

Experimental approaches to assess melanocytes mosaicism in segmental vitiligo

Vitiligo is an autoimmune disease of the skin that results in localized or disseminated white macules. One common feature of several existing classification protocols is the distribution of the disease into two main subtypes, non-segmental vitiligo (NSV) and segmental vitiligo (SV). SV is characterized by depigmentation spreading within one or more skin segments while NSV is widespread. Several clinical-epidemiological observations suggest that SV has distinct autoimmune pathophysiology compared to NSV. Furthermore, the clinical distribution pattern of SV lesions closely resembles other melanocyte mosaicism diseases. These observations led us to hypothesize that SV is caused by a localized autoimmune reaction targeting epidermal mosaicism melanocytes. Here, we proposed examples of experimental approaches to assess mosaicism in SV patients.