Yu-Li Su

Clinical utility of array comparative genomic hybridisation for prenatal diagnosis: a cohort study of 3171 pregnancies

Sir, We read with great interest your recent publication by Lee et al. on the use of array comparative genomic hybridisation (CGH) for prenatal diagnosis: a cohort study of 3171 pregnancies. Such a large cohort is an important contribution to the existing literature. It is important then to compare and contrast the results of Lee’s study with those of other recently published cohorts. The abstract states that when array CGH is performed for a fetus with a congenital anomaly apparent on prenatal ultrasound, the test was effective in identifying submicroscopic genomic imbalances (i.e. that are unidentifiable by conventional G-band karyotyping) in 33 of 194 (17%) cases. However, on reviewing data within table 2 (and later on in the abstract) this rate is recorded as 16/194 (8.2%). We attempted to extract data on submicroscopic copy number changes from table 2, but there appeared to have been formatting errors (e.g. in the row ‘pathogenic karyotyping reports’ the columns appear to be shifted a space to the right). It is unclear within the table how the calculated total of pathogenic karyotype and array CGH reports are constructed. We assume that pathogenic karyotype reports would be made up of those with numerical abnormality plus those with large chromosomal deletions and duplications, whereas pathogenic array reports would be made up of the former plus microscopic chromosomal deletions and duplications, plus variants of unknown significance. This, however, is not made clear. It is not certain whether there may have been instances where the array CGH test failed to identify a chromosomal anomaly detected by conventional karyotyping, and indeed whether both types of karyotype testing were performed for all fetuses included in the study. The authors state within the discussion that ‘when array CGH was performed alone no significantly pathological results were missed’, but without a reference test how could one be sure? Two array CGH platforms were used within this study: a 1-Mb bacterial artificial chromosome (BAC) and a 60-kb oligonucleotide array. It appears that there was a switch to the higher resolution 60-kb array towards the end of the cohort study. However, table 3 is not transparent to which array was used to detect which abnormal result. When extrapolating using the coordinates of the oligonucleotide probes in comparison with those of BAC probes aligned to the reference genome in ensembl, and in BlueGnome’s bluefuse multi database software, we predict that only one of the abnormal results detected by the higher resolution 60-kb array within Lee et al.’s cohort would have been missed by the 1-Mb BAC. This point should be commented on, as the lower resolution BAC would be predicted to produce less variants of unknown significance (VOUS), an important point to consider when using this technology on prenatal samples. The authors did not however state which array contributed to the five VOUS recorded. Finally, the authors conclude that there is a 0.52% baseline risk of submicroscopic genomic imbalance, even in women with an uneventful prenatal ultrasound examination. The authors conclude that prenatal array CGH is a recommended additional test in pregnant women undergoing invasive testing, but do not comment on the additional VOUS results that such testing could reveal, and the problems of interpretation and counselling of these variants in the prenatal setting. Before we can think about using this technology, even as an adjunct to conventional karyotypic testing, this issue must be addressed and the additional costs to overall pregnancy health care must be considered. j

A whole genome methylation analysis of systemic lupus erythematosus: hypomethylation of the IL10 and IL1R2 promoters is associated with disease activity

The etiology of systemic lupus erythematosus (SLE) involves a complex interaction of genetic and environmental factors. Investigations have shown that environmentally driven epigenetic changes contribute to the etiology of SLE. Here, we hypothesize that aberrant DNA methylation may contribute to the activation of the immune machinery and trigger lupus disease activity. A whole genome methylation array was applied to investigate the DNA methylation changes between 12 pairs of active SLE patients and healthy controls. The results were further confirmed in 66 SLE patients, 102 healthy controls. The methylation statuses of the IL10 and IL1R2 genes were significantly reduced in the SLE patient samples relative to the healthy controls (age-adjusted odds ratios, 64.2 and 16.9, respectively, P<0.0001). There was a trend toward SLE patients having hypomethylated IL10 and IL1R2 genes accompanied by greater disease activity. We observed that the methylation degree of IL10 and IL1R2 genes were reduced in the rheumatoid arthritis (RA) patients as well but the hypomethylation change was more significant in IL1R2 genes than in the IL10 genes in RA patients. This study demonstrated that DNA hypomethylation might be associated with SLE. Hypomethylated IL10 and IL1R2 genes may provide potential epigenetic markers as clinical predictors for autoimmune diseases.

Connective tissue growth factor linked to the E7 tumor antigen generates potent antitumor immune responses mediated by an antiapoptotic mechanism

A novel method for generating an antigen-specific cancer vaccine and immunotherapy has emerged using a DNA vaccine. However, antigen-presenting cells (APCs) have a limited life span, which hinders their long-term ability to prime antigen-specific T cells. Connective tissue growth factor (CTGF) has a role in cell survival. This study explored the intradermal administration of DNA encoding CTGF with a model tumor antigen, human papilloma virus type 16 E7. Mice vaccinated with CTGF/E7 DNA exhibited a dramatic increase in E7-specific CD4+ and CD8+ T-cell precursors. They also showed an impressive antitumor effect against E7-expressing tumors compared with mice vaccinated with the wild-type E7 DNA. The delivery of DNA encoding CTGF and E7 or CTGF alone could prolong the survival of transduced dendritic cells (DCs) in vivo. In addition, CTGF/E7-transduced DCs could enhance a higher number of E7-specific CD8+ T cells than E7-transduced DCs. By prolonging the survival of APCs, DNA vaccine encoding CTGF linked to a tumor antigen represents an innovative approach to enhance DNA vaccine potency and holds promise for cancer prophylaxis and immunotherapy.

Resolution of high uterine artery pulsatility index and notching following sildenafil citrate treatment in a growth‐restricted pregnancy

Fetal growth restriction (FGR) and pre-eclampsia remain the major causes of neonatal and maternal morbidity and mortality1. These two conditions have been shown to result from abnormal trophoblast invasion, which compromises uteroplacental circulation2. Uterine artery Doppler ultrasonography and a variety of proteins and hormones have been studied as potential early biomarkers of FGR or pre-eclampsia3. However, after identifying high-risk patients, management strategies are limited to increasing frequency of surveillance. Recent studies have demonstrated that sildenafil citrate significantly enhances vasodilation of myometrial small arteries and is also associated with fetal weight gain4–6, which offers a potential therapeutic possibility for FGR. We report here a case demonstrating improvement of uterine artery Doppler ultrasonography following sildenafil citrate treatment in a 26-week pregnancy with FGR.