Congenital anaemia associated with loss-of-function variants in DNA polymerase epsilon 1.

DNA polymerase epsilon (Pol ε), a component of the core replisome, is involved in DNA replication. Although genetic defects of Pol ε have been reported to cause immunodeficiency syndromes, its role in haematopoiesis remains unknown. Here, we identified compound heterozygous variants (p.[Asp1131fs];[Thr1891del]) in POLE, encoding Pol ε catalytic subunit A (POLE1), in siblings with a syndromic form of severe congenital transfusion-dependent anaemia. In contrast to Diamond-Blackfan anaemia, marked reticulocytopenia or marked erythroid hypoplasia was not found. Their bone marrow aspirates during infancy revealed erythroid dysplasia with strongly positive TP53 in immunostaining. Repetitive examinations demonstrated trilineage myelodysplasia within 2 years from birth. They had short stature and facial dysmorphism. HEK293 cell-based expression experiments and analyses of patient-derived induced pluripotent stem cells (iPSCs) disclosed a reduced mRNA level of Asp1131fs-POLE1 and defective nuclear translocation of Thr1891del-POLE1. Analysis of iPSCs showed compensatory mRNA upregulation of the other replisome components and increase of the TP53 protein, both suggesting dysfunction of the replisome. We created Pole-knockout medaka fish and found that heterozygous fishes were viable, but with decreased RBCs. Our observations expand the phenotypic spectrum of the Pol ε defect in humans, additionally providing unique evidence linking Pol ε to haematopoiesis.

A novel FLNA variant in a fetus with skeletal dysplasia.

Otopalatodigital spectrum disorder (OPDSD) is characterized by variable phenotypes, including skeletal dysplasia, and is caused by pathogenic variants in filamin A-encoding FLNA. FLNA variants associated with lethal OPDSD primarily alter the CH2 subdomain of the ABD of FLNA. Herein, we report a novel FLNA mutation in a fetus with severe skeletal dysplasia in a pregnant multigravida female with a history of repeated miscarriages and terminations.

Novel missense COL2A1 variant in a fetus with achondrogenesis type II.

Achondrogenesis type II (ACG2) is a lethal skeletal disorder caused by pathogenic variants in COL2A1. We present a fetus with cystic hygroma and severe shortening of the limbs at 14 weeks of gestation. We performed postnatal genetic analysis of the parents and fetus to diagnose the disease. A novel missense variant of COL2A1 [NM_001844.5: c.2987G>A, (p. Gly996Asp)] was identified, which led to the ACG2 diagnosis.

Monochorionic diamniotic twins of discordant external genitalia with 45,X/46,XY mosaicism.

BACKGROUND: Monozygotic twins with 45,X/46,XY mosaicism, discordant for phenotypic sex, are extremely rare. METHODS: This report describes the clinical findings of a rare case of 45,X/46,XY mosaicism in monozygotic twins with different external genitalia. Single nucleotide polymorphism (SNP) array analysis, performed by collecting DNA from each umbilical cord, showed identical SNPs in the autosomal chromosomes of both fetuses. RESULTS: Chorionic villus sampling of a 37-year-old primigravida carrying monozygotic twins revealed a 45,X/46,XY karyotype. Autopsy of the aborted fetuses revealed a penis and testes on one fetus and a vagina, uterus, and ovaries in the other fetus--which also had severe cystic hygroma. Cell counting using fluorescence in situ hybridization with XY probes (XY-FISH) showed 20% and 80% abundance of 45,X cells in the internal genitalia, liver, heart, lung, adrenal gland, bone marrow, and spine of the male and female fetuses, respectively. CONCLUSION: These results indicated that the fetuses were genetically monozygotic twins and their different degrees of mosaicism may have resulted in different genital phenotypes.

Epitranscriptomic profiling in human placenta: N6-methyladenosine modification at the 5'-untranslated region is related to fetal growth and preeclampsia.

Intracellular mRNA levels are not always proportional to their respective protein levels, especially in the placenta. This discrepancy may be attributed to various factors including post-transcriptional regulation, such as mRNA methylation (N6-methyladenosine: m6A). Here, we conducted a comprehensive m6A analysis of human placental tissue from neonates with various birth weights to clarify the involvement of m6A in placental biology. The augmented m6A levels at the 5'-untranslated region (UTR) in mRNAs of small-for-date placenta samples were dominant compared to reduction of m6A levels, whereas a decrease in m6A in the vicinity of stop codons was common in heavy-for-date placenta samples. Notably, most of these genes showed similar expression levels between the different birth weight categories. In particular, preeclampsia placenta samples showed consistently upregulated SMPD1 protein levels and increased m6A at 5'-UTR but did not show increased mRNA levels. Mutagenesis of adenosines at 5'-UTR of SMPD1 mRNAs actually decreased protein levels in luciferase assay. Collectively, our findings suggest that m6A both at the 5'-UTR and in the vicinity of stop codon in placental mRNA may play important roles in fetal growth and disease.

Essential Role of Lysophosphatidylcholine Acyltransferase 3 in the Induction of Macrophage Polarization in PMA-Treated U937 Cells.

Lysophospholipid acyltransferases (LPLATs) regulate the diversification of fatty acid composition in biological membranes. Lysophosphatidylcholine acyltransferases (LPCATs) are members of the LPLATs that play a role in inflammatory responses. M1 macrophages differentiate in response to lipopolysaccharide (LPS) and are pro-inflammatory, whereas M2 macrophages, which differentiate in response to interleukin-4 (IL-4), are anti-inflammatory and involved in homeostasis and wound healing. In the present study, we showed that LPCATs play an important role in M1/M2-macrophage polarization. LPS changed the shape of PMA-treated U937 cells from rounded to spindle shaped and upregulated the mRNA and protein expression of the M1 macrophage markers CXCL10, TNF-α, and IL-1ß. IL-4 had no effect on the shape of PMA-treated U937 cells and upregulated the M2 macrophage markers CD206, IL-1ra, and TGF-ß in PMA-treated U937 cells. These results suggest that LPS and IL-4 promote the differentiation of PMA-treated U937 cells into M1- and M2-polarized macrophages, respectively. LPS significantly downregulated the mRNA expression of LPCAT3, one of four LPCAT isoforms, and suppressed its enzymatic activity toward linoleoyl-CoA and arachidonoyl-CoA in PMA-treated U937 cells. LPCAT3 knockdown induced a spindle-shaped morphology typical of M1-polarized macrophages, and increased the secretion of CXCL10 and decreased the levels of CD206 in IL-4-activated U937 cells. This indicates that knockdown of LPCAT3 shifts the differentiation of PMA-treated U937 cells to M1-polarized macrophages. Our findings suggest that LPCAT3 plays an important role in M1/M2-macrophage polarization, providing novel potential therapeutic targets for the regulation of immune and inflammatory disorders.

Twin anemia-polycythemia sequence after laser surgery for twin-twin transfusion syndrome and maternal morbidity.

Twin anemia-polycythemia sequence (TAPS) is characterized by large inter-twin hemoglobin value differences without inter-twin amniotic fluid discordance. The management of post-laser TAPS remains controversial. Hence, more studies on TAPS, together with the associated maternal complications and outcome of the fetuses and infants are needed. Between 2003 and 2012, we performed 287 cases of fetoscopic laser photocoagulation for twin-twin transfusion syndrome. Among the 114 who were placed under our care until delivery, three cases of TAPS occurred. In one case, we conducted intrauterine intravenous transfusion, while in the other two cases, we adopted expectant management. We performed an emergency caesarean section at 27-30 weeks of gestation in all cases due to a severe condition of anemia in the TAPS donor. Two cases with antenatal TAPS stage 4 had severe maternal complications; one had minute pulmonary embolism, while the other had Mirror syndrome. All three pairs of infants survived. One TAPS donor and one TAPS recipient had neurodevelopmental impairment; bilateral deafness at 9.5 years old and spastic paralysis at 2 years old, respectively. In conclusion, post-laser TAPS in a higher stage can cause severe maternal complications. Close observations for both fetuses and mothers are required for such cases.