Fetal Dysmorphology-Still an Essential Art. Analysis of the Limitations of Microarray in a Fetal Population and a Look Toward the Genome Sequencing Era

Cytogenomic microarray allows assessment of the genome at higher resolutions than traditional karyotyping. The objective of this study is to evaluate the utility of microarray in a routine fetal autopsy setting before the advent of routine fetal exome/genome sequencing and the issues these technologies may generate. A systematic review of fetal postmortems at 12-24 weeks gestation between January 2011 and December 2014 was undertaken. Cases where there was no consent for audit, research, or genetic testing were excluded as were cases referred to the Procurator Fiscal, stillbirths, and neonatal deaths. Copy number variations were detected in 16 cases. In addition, there was 1 case of uniparental disomy; not all of these were related to the phenotype. There were a number of cases with phenotypic abnormalities and normal array results. Five of these underwent directed mutation analysis-3 were positive. Genetic laboratory investigations such as microarray and Quantitative Fluorescent-Polymerase Chain Reaction may increase the diagnostic yield in the assessment of fetal dysmorphology. However, this study shows that genetic results not only require careful review given the potential uncertain significance but also require phenotypic assessment of the fetus by a competent fetal dysmorphologist to determine the likely causative effect of any detected anomaly. This best practice will also extend to next generation sequencing and interpretation of variants of unknown significance. Fetal medicine teams should ideally include specialists well versed in assessment of fetal anomaly to provide families with the best possible information about the cause of their pregnancy loss and their options for future pregnancies.

Short report: Hyperammonaemia in critically ill septic infants

Three infants with subphrenic abscess, pyonephrosis, and obstructive ureterocoele respectively had grossly increased concentrations of plasma ammonia. This was considered to be a result of infections with urea splitting organisms. All died in spite of intensive care support, including specific measures to reduce plasma ammonia.

Demonstration of insulin production and storage in insulinomas by in situ hybridization and immunocytochemistry

Twelve cases of insulinoma were studied to assess the amount of hormone synthesis and hormone storage by the tumour and to see what effect a hormone-producing tumour has on the adjacent normal islets. This was investigated by performing in situ hybridization, which detects hormone messenger RNA, thus giving an indication of the degree of hormone synthesis by the tumour, and immunocytochemistry, which detects the hormone itself, thus giving an indication of the amount of hormone stored in the tumour cells. It was found that in most cases there was less hormone stored within the tumour cells than in adjacent islet cells. In a minority of cases, this decrease in stored hormone was associated with reduced hormone synthesis, but the majority of cases showed either equivalent or increased levels of hormone mRNA in the tumour cells compared with adjacent islets. In addition, it was noted that, unlike some other endocrine organs, the presence of a hormone-producing tumour within the pancreas did not appear to inhibit hormone synthesis in the adjacent normal tissue.

Is beta-APP a marker of axonal damage in short-surviving head injury?

beta-Amyloid precursor protein (beta-APP), a normal constituent of neurons which is conveyed by fast axonal transport, has been found to be a useful marker for axonal damage in cases of fatal head injury. Immunocytochemistry for beta-APP is a more sensitive technique for identifying axonal injury than conventional silver impregnation. This study was designed to determine how quickly evidence of axonal damage and bulb formation appears. Using this method a variety of brain areas were studied from 55 patients who died within 24 h of a head injury. Immunocytochemical evidence of axonal injury was first detected after 2 h survival, axonal bulbs were first identified after 3 h survival, and the amount of axonal damage and axonal bulb formation increased the longer the survival time.

Demonstration of renin gene expression in nephroblastoma by in situ hybridization

Most patients with nephroblastoma have high levels of plasma renin and some are hypertensive. Blood pressure falls after removal of the affected kidney, suggesting that nephroblastoma is associated with renin production either by the tumour or by the kidney. In this study, direct evidence was sought of renin gene expression in nephroblastoma using in situ hybridization. Digoxigenin-labelled riboprobes and an immunoperoxidase technique were used to detect cells containing renin mRNA: this showed renin gene expression in 9 out of 12 cases. There were positive cells within metanephric blastema and in occasional neoplastic glomeruloid structures, confirming that in seven cases nephroblastoma tumour cells expressed the renin gene. However, renin gene expression was also demonstrated in perivascular cells of uncertain lineage in seven cases; in five cases there was evidence of renin gene expression in both tumour cells and perivascular cells. The latter finding raises the possibility that some of the cells expressing the renin gene could be stromal cells. It is concluded that nephroblastomas contain cells that express the renin gene and that some are tumour cells, while other perivascular cells may be stromal cells.

Expression of carcinoembryonic antigen, T-antigen, and oncogene products as markers of neoplastic and preneoplastic colonic mucosa

Several crypt abnormalities have been demonstrated in the mucosa of neoplastic and preneoplastic lesions of the large intestine. In addition, certain tumor markers are expressed in large intestinal carcinoma but not in normal mucosa. To determine whether any correlation exists between tumor marker expression and crypt abnormalities and at what stage markers are expressed, we studied specimens of large intestinal mucosa from 13 patients with preneoplastic conditions (adenomatous polyp, familial polyposis, Crohn's disease, and ulcerative colitis). The tumor markers examined include carcinoembryonic antigen (CEA), the ras gene products p21 and p21ser (mutated form), and beta-D-galactosyl-(1----3)-alpha-N-acetyl-D-galactosamine (gal--gal NAc, also known as T-antigen). Results were compared to those of five cases of adenocarcinoma of colon and three control cases of colonic mucosa obtained at immediate autopsy. All four markers were expressed in three of the five cases of adenocarcinoma, but none were expressed in the control cases. Variable expression of each marker was demonstrated in the dilated, distorted crypts of preneoplastic lesions. CEA and gal--gal NAc appeared to be expressed most frequently, suggesting that these are common markers or are expressed at an earlier stage in the neoplastic process than p21 or p21ser. Demonstration of such markers in preneoplastic conditions may be of use in determining the malignant potential and in monitoring these lesions.