Retrospective UK multicentre study of the pregnancy outcomes of women with a Fontan repair.

BACKGROUND: The population of women of childbearing age palliated with a Fontan repair is increasing. The aim of this study was to describe the progress of pregnancy and its outcome in a cohort of patients with a Fontan circulation in the UK. METHODS: A retrospective study of women with a Fontan circulation delivering between January 2005 and November 2016 in 10 specialist adult congenital heart disease centres in the UK. RESULTS: 50 women had 124 pregnancies, resulting in 68 (54.8%) miscarriages, 2 terminations of pregnancy, 1 intrauterine death (at 30 weeks), 53 (42.7%) live births and 4 neonatal deaths. Cardiac complications in pregnancies with a live birth included heart failure (n=7, 13.5%), arrhythmia (n=6, 11.3%) and pulmonary embolism (n=1, 1.9%). Very low baseline maternal oxygen saturations at first obstetric review were associated with miscarriage. All eight women with saturations of less than 85% miscarried, compared with 60 of 116 (51.7%) who had baseline saturations of ≥85% (p=0.008). Obstetric and neonatal complications were common: preterm delivery (n=39, 72.2%), small for gestational age (<10th percentile, n=30, 55.6%; <5th centile, n=19, 35.2%) and postpartum haemorrhage (n=23, 42.6%). There were no maternal deaths in the study period. CONCLUSION: Women with a Fontan circulation have a high rate of miscarriage and, even if pregnancy progresses to a viable gestational age, a high rate of obstetric and neonatal complications.

Sequence variation in promoter of Ica1 gene, which encodes protein implicated in type 1 diabetes, causes transcription factor autoimmune regulator (AIRE) to increase its binding and down-regulate expression.

ICA69 (islet cell autoantigen 69 kDa) is a protein implicated in type 1 diabetes mellitus in both the non-obese diabetic (NOD) mouse model and humans. ICA69 is encoded by the Ica1 gene on mouse chromosome 6 A1-A2. We previously reported reduced ICA69 expression in the thymus of NOD mice compared with thymus of several non-diabetic mouse strains. We propose that reduced thymic ICA69 expression could result from variations in transcriptional regulation of the gene and that polymorphisms within the Ica1 core promoter may partially determine this transcriptional variability. We characterized the functional promoter of Ica1 in NOD mice and compared it with the corresponding portions of Ica1 in non-diabetic C57BL/6 mice. Luciferase reporter constructs demonstrated that the NOD Ica1 promoter region exhibited markedly reduced luciferase expression in transiently transfected medullary thymus epithelial (mTEC(+)) and B-cell (M12)-derived cell lines. However, in a non-diabetic strain, C57BL/6, the Ica1 promoter region was transcriptionally active when transiently transfected into the same cell lines. We concomitantly identified five single nucleotide polymorphisms within the NOD Ica1 promoter. One of these single nucleotide polymorphisms increases the binding affinity for the transcription factor AIRE (autoimmune regulator), which is highly expressed in thymic epithelial cells, where it is known to play a key role regulating self-antigen expression. We conclude that polymorphisms within the NOD Ica1 core promoter may determine AIRE-mediated down-regulation of ICA69 expression in medullary thymic epithelial cells, thus providing a novel mechanistic explanation for the loss of immunologic tolerance to this self-antigen in autoimmunity.