AN INSIGHT INTO - HEMIFACIAL MICROSOMIA

Hemifacial microsomia is a common birth defect involving first and second branchial arch derivatives. The phenotype is highly variable. In addition to craniofacial anomalies, there may be cardiac, vertebral, and central nervous system defects. Most cases are sporadic, but there are rare familial cases that exhibit autosomal dominant inheritance.

The Assessment of the Usefulness of Prenatal Magnetic Resonance Imaging in the Diagnosis of Central Nervous System Defects

Central nervous system (CNS) abnormalities cause about 40% of infant deaths in the first year of life. In case of the detection of abnormalities by ultrasound, a pregnant woman should be offered prenatal magnetic resonance imaging (pMRI). The aims of our study were: (1) to evaluate the effectiveness of pMRI in the diagnosis of selected fetal CNS defects; and (2) to assess the possibility of replacing postnatal tests with prenatal magnetic resonance. The prospective and observational study was conducted between 2014 and 2017 at the University Hospital in Krakow. Patients with suspected CNS defects of the fetus were qualified for pMRI in the third trimester of pregnancy. Sixty patients were included in the study group. Prenatal MRI was characterized by low accuracy in the diagnosis of complex brain defects. Cohen’s kappa coefficient κ = 0.21 (95% CI 0.00–0.46). No evidence was found suggesting the replacement of postnatal tests with pMRI. MRI was characterized by low consistency of diagnoses in the case of complex brain defects. The possibility of replacing postnatal studies with pMRI was not supported.

Novel Pathogenic Variants in LHX3, LHX4 and GLI2 Identified in Pediatric Patients With Congenital Hypopituitarism: From Variant Calling To Variant Testing

Congenital hypopituitarism (CH), septo-optic dysplasia (SOD), and holoprosencephaly (HPE) constitute an important group of structural birth defects that cause significant morbidity and life-long consequences for quality of life and care. The genetic causes are highly overlapping. As such, these disorders can be considered as a spectrum of related disorders. Improved insight into genetic causes would be valuable for patients, families, and medical geneticists. Very few systematic genetic screens have been carried out for patients with CH. We implemented genetic screening using single-molecule molecular inversion probes sequencing to identify causative mutations in a set of 67 genes previously reported in CH patients and the spectrum encompassing SOD and HPE. We captured genomic DNA from 170 Argentinean pediatric patients with CH, and 54% of the patients in this cohort have craniofacial, ophthalmologic, and/or central nervous system defects. We found candidate pathogenic, likely pathogenic and variants uncertain significance (VUS) in 23% of the cases. In order to evaluate the functional consequences of VUS in LHX3, LHX4, and GLI2, we performed in-vitro functional assays to study the activity of the mutated proteins. To test LHX3/4 variants we co-transfected HEK293T cells with wild type (WT) or mutated LHX3/4 variant plasmids and luciferase reporter genes driven by the ɑGSU promoter or GH1 promoter and assayed for luciferase activity. For GLI2 functional analysis we used the cell line NIH/3T3-CG, stably transfected to express GFP under the presence of GLI2 activated form. Endogenous Gli2 was knocked out by CRISPR-Cas9 and clones were selected for absence of GFP expression upon activation of the sonic hedgehog pathway. We tested the ability of transfected WT or mutated GLI2 expression plasmids to restore GFP fluorescence. We concluded that variants LHX3:p.Pro187Ser LHX4:p.Arg84His, p.Gln100His and p.Trp204Leu and GLI2:p.1404Lfs impair activation of the reporter gene, while the LHX3:p.Leu220Met and GLI2:p.L761P have WT activity on their respective assays. Identification of disease-causing variants in CH is complicated by phenotypic variation, incomplete penetrance, and VUS. Functional testing of potentially pathogenic variants is critical to arrive at a definitive molecular diagnosis. A full catalogue of variant effects in known causative genes would be invaluable for clinicians in order to simplify the interpretation of novel variants and reduce the diagnostic odyssey that families often experience.

Hypoglossal Nerve Abnormalities as Biomarkers for Central Nervous System Defects in Mouse Lines Producing Embryonically Lethal Offspring

An essential step in researching human central nervous system (CNS) disorders is the search for appropriate mouse models that can be used to investigate both genetic and environmental factors underlying the etiology of such conditions. Identification of murine models relies upon detailed pre- and post-natal phenotyping since profound defects are not only the result of gross malformations but can be the result of small or subtle morphological abnormalities. The difficulties in identifying such defects are compounded by the finding that many mouse lines show quite a variable penetrance of phenotypes. As a result, without analysis of large numbers, such phenotypes are easily missed. Indeed for null mutations, around one-third have proved to be pre- or perinatally lethal, their analysis resting entirely upon phenotyping of accessible embryonic stages.To simplify the identification of potentially useful mouse mutants, we have conducted three-dimensional phenotype analysis of approximately 500 homozygous null mutant embryos, produced from targeting a variety of mouse genes and harvested at embryonic day 14.5 as part of the “Deciphering the Mechanisms of Developmental Disorders” www.dmdd.org.uk program. We have searched for anatomical features that have the potential to serve as biomarkers for CNS defects in such genetically modified lines. Our analysis identified two promising biomarker candidates. Hypoglossal nerve (HGN) abnormalities (absent, thin, and abnormal topology) and abnormal morphology or topology of head arteries are both frequently associated with the full spectrum of morphological CNS defects, ranging from exencephaly to more subtle defects such as abnormal nerve cell migration. Statistical analysis confirmed that HGN abnormalities (especially those scored absent or thin) indeed showed a significant correlation with CNS defect phenotypes. These results demonstrate that null mutant lines showing HGN abnormalities are also highly likely to produce CNS defects whose identification may be difficult as a result of morphological subtlety or low genetic penetrance.

A Role of Microtubules in Oligodendrocyte Differentiation

Oligodendrocytes are specialized cells that myelinate axons in the central nervous system. Defects in oligodendrocyte function and failure to form or maintain myelin sheaths can cause a number of neurological disorders. Oligodendrocytes are differentiated from oligodendrocyte progenitor cells (OPCs), which extend several processes that contact, elaborate, and eventually wrap axonal segments to form multilayered myelin sheaths. These processes require extensive changes in the cytoarchitecture and must be regulated by reorganization of the cytoskeleton. Here, we established a simple protocol to isolate and differentiate mouse OPCs, and by using this method, we investigated a role of microtubules (MTs) in oligodendrocyte differentiation. Oligodendrocytes developed a complex network of MTs during differentiation, and treatment of differentiating oligodendrocytes with nanomolar concentrations of MT-targeting agents (MTAs) markedly affected oligodendrocyte survival and differentiation. We found that acute exposure to vincristine and nocodazole at early stages of oligodendrocyte differentiation markedly increased MT arborization and enhanced differentiation, whereas taxol and epothilone B treatment produced opposing outcomes. Furthermore, treatment of myelinating co-cultures of oligodendrocytes and neurons with nanomolar concentrations of MTAs at late stages of oligodendrocyte differentiation induced dysmyelination. Together, these results suggest that MTs play an important role in the survival, differentiation, and myelination of oligodendrocytes.

Inflammatory Bowel Disease and Risk of Birth Defects in Offspring

Background and Aims The relationship between inflammatory bowel disease in pregnancy and birth defects is not understood. We evaluated whether Crohn’s disease and ulcerative colitis in pregnant women were associated with the risk of birth defects in the offspring. Methods We undertook a retrospective cohort study of 2 184 888 pregnancies in Quebec, Canada, between 1989 and 2016. We calculated risk ratios [RR] and 95% confidence intervals [CI] for the association between inflammatory bowel disease and the risk of birth defects, using generalised estimating equations adjusted for maternal characteristics. We assessed associations in the period before 2000, when immunosuppressive biologic therapy and folic acid food fortification were not yet available, compared with the period after 2000 when these interventions were more widespread. Results This study included 13 099 women with Crohn’s disease and 7798 with ulcerative colitis. Crohn’s disease was associated with 1.90 times [95% CI 1.10–3.28] the risk of abdominal wall defects [gastroschisis, omphalocoele, and diaphragmatic hernia] and ulcerative colitis was associated with 1.53 times [95% CI 1.02–2.30] the risk of central nervous system defects. The association of Crohn’s disease with abdominal wall defects was stronger before 2000 [RR 3.62, 95% CI 1.71–7.67] than after 2000 [RR 1.23, 95% CI 0.55–2.75]. Ulcerative colitis was associated with central nervous system defects regardless of time period. Conclusions These findings suggest that inflammatory bowel disease is associated with the risk of abdominal wall and central nervous system defects, and that introduction of immunobiologic medications is unlikely to be associated with added risk. Podcast This article has an associated podcast which can be accessed at https://academic.oup.com/ecco-jcc/pages/podcast

Markers of the pathological course of perinatal period in children with echogenic intracardiac focus

Aim: to describe the course of perinatal period in children with echogenic intracardiac focus (EIF) diagnosed in the antenatal period.Patients and Methods: in this case-control study, the groups were similar in age, obstetric history, and somatic status of mothers. Group 1 included 214 pregnant women whose fetus (newborn later) was diagnosed with EIF. Inclusion criteria were an echoic focus within the fetal heart (by prenatal ultrasound) as well as pregnancy follow-up and childbirth in the Perinatal Center of Tyumen city. Group 2 included 107 pregnant women whose fetus (newborn later) had no this sonographic sign. Retrospective analysis of the course of antenatal and intranatal periods of newborns with EIF was performed. The course of early neonatal period was described. Placental histology (n = 69) and autopsies of perinatal losses (n=12) were discussed.Results: it was demonstrated that EIFs identified for the first time after 20 weeks of gestation persist after delivery much more common (p<0.01) when associated with impaired fetoplacental circulation. More than 50% of mothers (p>0.01) whose fetuses were diagnosed with EIF had patho-logical pregnancy. During the delivery, clinical signs of chronic hypoxia in newborns with EIF were identified twice as common as in newborns without EIF (p=0.029). Moreover, none of the children had typical signs of Down syndrome while the number of preterm newborns was simi-lar (p>0.05). Only newborns with EIF were diagnosed with different types of birth defects (7.94%) and generalized cytomegalovirus infection (1.46%). Hypoxic cardiopathy (that illustrates cardiovascular deadaptation) was 3.2 times more common in newborns with EIF (p=0.005) Conclusion: combination of EIF (2.67±0.9 mm) localized in the left or right ventricle and other sonographic signs, central nervous system defects and/or cardiovascular abnormalities require screening for perinatal infections as well as uterine and umbilical artery Doppler to minimize the risk of perinatal events.Keywords: perinatal period, echogenic intracardiac focus, newborns, perinatal losses, congenital anomaly, hypoxic cardiopathy, sonographic sign.For citation: Malinina E.I., Rychkova O.A., Chernysheva T.V. Markers of the pathological course of perinatal period in children with echogenic intracardiac focus. Russian Journal of Woman and Child Health. 2020;3(2):132–135. DOI: 10.32364/2618-8430-2020-3-2-132-135.