Objective To derive a longitudinal gestational reference range for amniotic fluid index and to compare it with the established cross‐sectional reference range. Design Longitudinal prospective study. Setting Liverpool Maternity Hospital and Mill Road Maternity Hospital, both teaching hospitals in central Liverpool. Subjects One hundred and fifteen pregnant women, in whom the expected date by the last menstrual period and ultrasound scan at 18 to 19 weeks were in agreement by seven days, were recruited. They were divided into two groups and scanned at four weekly intervals as follows: Group A: scanned at 20, 24, 28, 32, 36, 40; and Group B: scanned at 22, 26, 30, 34, 38, 42. Results Amniotic fluid index varies with gestation, rising from early gestation to peak at 30 weeks and then falling from 36 to 42 weeks. Comparison of our reference range with that of Moore and Cayle (1990) shows obvious differences at the lower limit. Conclusion We have established a normal longitudinal reference range for the amniotic fluid index. Our ranges, derived from longitudinal data, would seem a more appropriate reference than the established reference ranges derived from cross‐sectional data. In particular, the differences at the lower limits may have considerable clinical implication in the use of amniotic fluid index in the prediction of fetal compromise.
qPCR was not found to be an effective tool for RHD genotyping in suboptimal samples (<2% cffDNA). However, when testing the same suboptimal samples on the same day by dPCR, 100% sensitivity was achieved for both fetal sex determination and RHD genotyping. Use of dPCR for identification of fetal specific markers can reduce the occurrence of false-negative and inconclusive results, particularly when samples express high levels of background maternal cell-free DNA.
We report what we believe is the first percutaneous transvenous intracardiac cardiac pacing of a fetus. The case is important because it demonstrates that transvenous fetal cardiac pacing is technically possible and provides a basis for development of the technology.
Transient receptor potential vanilloid 6 (TRPV6) functions in tetramer form for calcium transport. Until now, TRPV6 has not been linked with skeletal development disorders. An infant with antenatal onset thoracic insufficiency required significant ventilatory support. Skeletal survey showed generalized marked undermineralization, hypoplastic fractured ribs, metaphyseal fractures, and extensive periosteal reaction along femoral, tibial, and humeral diaphyses. Parathyroid hormone (PTH) elevation (53.4-101 pmol/L) initially suggested PTH signaling disorders. Progressively, biochemical normalization with radiological mineralization suggested recovery from in utero pathophysiology. Genomic testing was undertaken and in silico protein modeling of variants. No abnormalities in antenatal CGH array or UPD14 testing. Postnatal molecular genetic analysis found no causative variants in CASR, GNA11, APS21, or a 336 gene skeletal dysplasia panel investigated by whole exome sequencing. Trio exome analysis identified compound heterozygous TRPV6 likely pathogenic variants: novel maternally inherited missense variant, c.1978G > C p.(Gly660Arg), and paternally inherited nonsense variant, c.1528C > T p.(Arg510Ter), confirming recessive inheritance. p.(Gly660Arg) generates a large side chain protruding from the C-terminal hook into the interface with the adjacent TRPV6 subunit. In silico protein modeling suggests steric clashes between interface residues, decreased C-terminal hook, and TRPV6 tetramer stability. The p.(Gly660Arg) variant is predicted to result in profound loss of TRPV6 activity. This first case of a novel dysplasia features severe but improving perinatal abnormalities. The TRPV6 compound heterozygous variants appear likely to interfere with fetoplacental calcium transfer crucial for in utero skeletal development. Astute clinical interpretation of evolving perinatal abnormalities remains valuable in complex calcium and bone pathophysiology and informs exome sequencing interpretation.
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