In a Genomic Era, Placental Pathology Still Holds the Key in the Nondysmorphic Stillbirth.

Objective To explore the relative utility of genetic testing in contrast to placental pathology in explaining causation of death in the structurally normal stillborn population. Methods A retrospective review of a structurally normal stillborn infant cohort in South East Scotland between 2011 and 2015, defined by death at or after 24 weeks of gestation. We reviewed pathology reports and collected demographic data on cases. This information was collated with genetic test results (quantitative fluorescent polymerase chain reaction and microarray analysis) and placental pathology to create a database for analysis. Primary Results Within the structurally normal population (n = 131), there were 125 genetic tests performed and 11 abnormal results. Sixty-six microarray analyses were performed, and 2 (3%) of the results were thought likely to reflect cause of stillbirth (1 case of incomplete trisomy 4 and 1 case of deletion of chromosome Xp in a female). Analysis was significantly limited in 2 cases as parental samples were not available. The placental pathology was available in a total of 129 cases; significant findings were identified in 100 cases; 79 (61%) showed changes that were considered to have caused death (including cord "accidents"), and a further 21 (16%) showed findings likely to influence the management of subsequent pregnancies. Conclusions We reaffirm the utility of placental examination in the investigation of stillbirth. In cases of nondysmorphic stillbirth where placental pathology does not explain the cause of stillbirth, microarray analysis of fetal DNA can add further diagnostic information in 3% of cases but can add further diagnostic confusion, and it is important that parental bloods are taken to minimize this risk.

An Internet-based external quality assessment in cytogenetics that audits a laboratory's analytical and interpretative performance.

A novel approach to external quality assessment (EQA) using the Internet mimics the diagnostic situation so that multiple tests can be requested and EQA cases can be 'tailor made' to address a specific chromosome syndrome, disease, or clinical dilemma. The web-based EQA system was trialled on a large UK EQA scheme, UK NEQAS for Clinical Cytogenetics. It has also been used to implement a new Cytogenetics European Quality Assessment scheme, CEQA, set up with the intention of providing laboratories in countries without access to a local EQA scheme the opportunity of participation in EQA. Overall, Internet-based EQA allows for a varied EQA programme. Poor performance was detected in both CEQA and UK NEQAS constitutional EQA schemes and also in the UK NEQAS oncology EQA scheme. The Internet-based EQA overcomes submission delays due to international surface mail. There is also a reduction in administration and assessors' time compared to a retrospective EQA involving the submission of unique cases for EQA assessment, as participants analyse the same three Internet-based EQA cases simultaneously. Many EU27 (EU member states) laboratories still do not participate in their national EQA schemes, so until EQA participation becomes mandatory as a component of compulsory laboratory accreditation, the quality of laboratory diagnostic service is unpredictable.

Diagnosing idiopathic learning disability: a cost-effectiveness analysis of microarray technology in the National Health Service of the United Kingdom.

Array based comparative genomic hybridisation (aCGH) is a powerful technique for detecting clinically relevant genome imbalance and can offer 40 to > 1000 times the resolution of karyotyping. Indeed, idiopathic learning disability (ILD) studies suggest that a genome-wide aCGH approach makes 10-15% more diagnoses involving genome imbalance than karyotyping. Despite this, aCGH has yet to be implemented as a routine NHS service. One significant obstacle is the perception that the technology is prohibitively expensive for most standard NHS clinical cytogenetics laboratories. To address this, we investigated the cost-effectiveness of aCGH versus standard cytogenetic analysis for diagnosing idiopathic learning disability (ILD) in the NHS. Cost data from four participating genetics centres were collected and analysed. In a single test comparison, the average cost of aCGH was pound442 and the average cost of karyotyping was pound117 with array costs contributing most to the cost difference. This difference was not a key barrier when the context of follow up diagnostic tests was considered. Indeed, in a hypothetical cohort of 100 ILD children, aCGH was found to cost less per diagnosis ( pound3,118) than a karyotyping and multi-telomere FISH approach ( pound4,957). We conclude that testing for genomic imbalances in ILD using microarray technology is likely to be cost-effective because long-term savings can be made regardless of a positive (diagnosis) or negative result. Earlier diagnoses save costs of additional diagnostic tests. Negative results are cost-effective in minimising follow-up test choice. The use of aCGH in routine clinical practice warrants serious consideration by healthcare providers.

Using BAC clones to characterize unbalanced chromosome abnormalities in interphase cells.

Carriers of balanced translocations usually carry alterations in gene sequences, which lead to dysfunction during early and late embryogenesis. Related spatial rearrangement causes either cumulative delay in cell cycles and/or anomalies in transcription and translation. This has also an important impact at the time of genomic activation, the longest cell cycle of preimplantation development. Carrier patients may be affected either with primary infertility or by repeated miscarriages [Hum. Reprod. 12 (1997) 2019.]. Assuming that a fraction of the germ cells is karyotypically normal, these patients would greatly benefit from efficient procedures for generation and use of breakpoint-specific DNA hybridisation probes in preconception and preimplantation genetic diagnosis (PGD) after polar body or blastomere biopsy of the embryos. The objective of this research was to design an approach of patient-specific probes for preimplantation diagnosis of chromosome translocations and which could be used eventually to select chromosomally normal embryos from balanced or unbalanced interphase cells prior to their transfer to the mother's womb. This approach was used for a couple, where the female partner was a carrier of a balanced translocation 46,XX,t(4;12)(p16.1;q24.31). First, BAC/PAC clones were chosen from specific chromosome bands from the genome sequence that hybridise adjacent to the chromosomal breakpoints or span them. Then, the probes and hybridisation conditions were optimised using unrelated normal amniocytes, lymphoblastoid cells and lymphocytes from the carrier to increase hybridisation signal intensity and decrease background. Finally, the probes were tested on target cells before they were used for mimicking preconception or preimplantation genetic diagnosis. Three slides were analysed blindly from a normal karyotype, an unbalanced and a balanced translocation. A total of 78 cells were analysed of which in the slide A 19/22 (86%) were found to be unbalanced, in slide B 25/31 (81%) were normal and in slide C 21/25 (84%) were balanced. Thus, it was demonstrated that cells with known structural abnormalities could be detected, based on hybridisation of breakpoint spanning bacterial artificial chromosome (BAC) DNA probes in interphase cells.

3q29 microdeletion syndrome: clinical and molecular characterization of a new syndrome.

We report the identification of six patients with 3q29 microdeletion syndrome. The clinical phenotype is variable despite an almost identical deletion size. The phenotype includes mild-to-moderate mental retardation, with only slightly dysmorphic facial features that are similar in most patients: a long and narrow face, short philtrum, and high nasal bridge. Autism, gait ataxia, chest-wall deformity, and long and tapering fingers were noted in at least two of six patients. Additional features--including microcephaly, cleft lip and palate, horseshoe kidney and hypospadias, ligamentous laxity, recurrent middle ear infections, and abnormal pigmentation--were observed, but each feature was only found once, in a single patient. The microdeletion is approximately 1.5 Mb in length, with molecular boundaries mapping within the same or adjacent bacterial artificial chromosome (BAC) clones at either end of the deletion in all patients. The deletion encompasses 22 genes, including PAK2 and DLG1, which are autosomal homologues of two known X-linked mental retardation genes, PAK3 and DLG3. The presence of two nearly identical low-copy repeat sequences in BAC clones on each side of the deletion breakpoint suggests that nonallelic homologous recombination is the likely mechanism of disease causation in this syndrome.