Temporal Relationship Between Increased Nuchal Translucency and Enlarged Jugular Lymphatic Sac

Cardiac defects, nuchal edema and abnormal lymphatic development are not associated with morphological changes in the ductus venosus

BACKGROUND

In human fetuses with cardiac defects and increased nuchal translucency, abnormal ductus venosus flow velocity waveforms are observed. It is unknown whether abnormal ductus venosus flow velocity waveforms in fetuses with increased nuchal translucency are a reflection of altered cardiac function or are caused by local morphological alterations in the ductus venosus.

AIM

The aim of this study was to investigate if the observed increased nuchal translucency, cardiac defects and abnormal lymphatic development in the examined mouse models are associated with local changes in ductus venosus morphology.

STUDY DESIGN

Mouse embryos with anomalous lymphatic development and nuchal edema (Ccbe1(-/-) embryos), mouse embryos with cardiac defects and nuchal edema (Fkbp12(-/-), Tbx1(-/-), Chd7(fl/fl);Mesp1Cre, Jarid2(-/-NE+) embryos) and mouse embryos with cardiac defects without nuchal edema (Tbx2(-/-), Fgf10(-/-), Jarid2(-/-NE-) embryos) were examined. Embryos were analyzed from embryonic day (E) 11.5 to 15.5 using markers for endothelium, smooth muscle actin, nerve tissue and elastic fibers.

RESULTS

All mutant and wild-type mouse embryos showed similar, positive endothelial and smooth muscle cell expression in the ductus venosus at E11.5-15.5. Nerve marker and elastic fiber expression were not identified in the ductus venosus in all investigated mutant and wild-type embryos. Local morphology and expression of the used markers were similar in the ductus venosus in all examined mutant and wild-type embryos.

CONCLUSIONS

Cardiac defects, nuchal edema and abnormal lymphatic development are not associated with morphological changes in the ductus venosus. Ductus venosus flow velocity waveforms most probably reflect intracardiac pressure.

Absence of an anatomical origin for altered ductus venosus flow velocity waveforms in first-trimester human fetuses with increased nuchal translucency

OBJECTIVE

To perform a morphological evaluation of the ductus venosus, heart and jugular lymphatic sac (JLS) in first-trimester human fetuses with normal and abnormal ductus venosus flow velocity waveforms (DV-FVWs) and normal and increased nuchal translucency (NT).

METHOD

Postmortem examination was performed on fetuses with increased NT or structural malformations with previous NT and DV-FVW measurements. Ductus venosus morphology was examined using markers for endothelium, smooth muscle actin (SMA), nerves and elastic fibers. Fetal hearts were studied by microscopy. The nuchal region was analyzed using markers for lymphatic vessels, endothelium, SMA and nerves.

RESULTS

Two trisomy 21 and two trisomy 18 fetuses with increased NT and abnormal DV-FVWs were analyzed. As a control, one euploid anencephalic fetus with normal NT, cardiac anatomy and DV-FVWs was examined. Similar endothelial and SMA expression was observed in the ductus venosus in all fetuses. Nerve and elastic fiber expression were not detected. Three trisomic fetuses showed cardiac defects, one trisomic fetus demonstrated normal cardiac anatomy. The JLS was abnormally enlarged or contained red blood cells in all trisomic fetuses. The control fetus showed a normal JLS.

CONCLUSION

Abnormal DV-FVWs are not justified by alterations in ductus venosus morphology. DV-FVWs most probably reflect intracardiac pressure. © 2016 John Wiley & Sons, Ltd.

New BRAF knockin mice provide a pathogenetic mechanism of developmental defects and a therapeutic approach in cardio-facio-cutaneous syndrome

Cardio-facio-cutaneous (CFC) syndrome is one of the 'RASopathies', a group of phenotypically overlapping syndromes caused by germline mutations that encode components of the RAS-MAPK pathway. Germline mutations in BRAF cause CFC syndrome, which is characterized by heart defects, distinctive facial features and ectodermal abnormalities. To define the pathogenesis and to develop a potential therapeutic approach in CFC syndrome, we here generated new knockin mice (here Braf(Q241R/+)) expressing the Braf Q241R mutation, which corresponds to the most frequent mutation in CFC syndrome, Q257R. Braf(Q241R/+) mice manifested embryonic/neonatal lethality, showing liver necrosis, edema and craniofacial abnormalities. Histological analysis revealed multiple heart defects, including cardiomegaly, enlarged cardiac valves, ventricular noncompaction and ventricular septal defects. Braf(Q241R/+) embryos also showed massively distended jugular lymphatic sacs and subcutaneous lymphatic vessels, demonstrating lymphatic defects in RASopathy knockin mice for the first time. Prenatal treatment with a MEK inhibitor, PD0325901, rescued the embryonic lethality with amelioration of craniofacial abnormalities and edema in Braf(Q241R/+) embryos. Unexpectedly, one surviving pup was obtained after treatment with a histone 3 demethylase inhibitor, GSK-J4, or NCDM-32b. Combination treatment with PD0325901 and GSK-J4 further increased the rescue from embryonic lethality, ameliorating enlarged cardiac valves. These results suggest that our new Braf knockin mice recapitulate major features of RASopathies and that epigenetic modulation as well as the inhibition of the ERK pathway will be a potential therapeutic strategy for the treatment of CFC syndrome.

Abnormal ductus venosus flow in first-trimester fetuses with increased nuchal translucency: relationship with the type of cardiac defect?

OBJECTIVE

The purpose of this study was to evaluate ductus venosus flow velocities and a possible relationship with the type of cardiac defect in fetuses with increased nuchal translucency (NT).

METHODS

Seventy-two fetuses with normal NT and 137 fetuses with increased NT (>95th percentile) were evaluated. The ductus venosus pulsatility index for veins (PIV), late diastolic velocity (velocity during atrial contraction [a-V]), and intracardiac velocities were evaluated. In cases of pregnancy termination, a postmortem examination was performed. Cardiac defects were grouped into septal defects, left and right inflow obstruction, left and right outflow obstruction, and other defects. Data were evaluated by multilevel analysis.

RESULTS

A cardiac defect was found in 45 fetuses with increased NT. Fetuses with increased NT showed a higher ductus venosus PIV and a lower a-V compared to fetuses with normal NT (P < .05). Within the group of fetuses with increased NT, a higher PIV and a lower a-V were found in cases with a cardiac defect compared to cases with a normal heart (P < .001). No differences in PIV and a-V were found between the types of cardiac defects. Intracardiac velocities showed no differences between fetuses with normal and increased NT, irrespective of the presence of a cardiac defect.

CONCLUSIONS

Ductus venosus flow velocities in fetuses with increased NT are not related to a certain type of cardiac defect. This indicates that the altered ductus venosus flow velocities found in fetuses with increased NT cannot be explained by cardiac failure due to a specific altered cardiac anatomy.

Altered jugular vein and ductus venosus flow velocities in fetuses with increased nuchal translucency and distended jugular lymphatic sacs

OBJECTIVE

We sought to assess blood flow in relation to jugular lymphatic distension in fetuses with increased and normal nuchal translucency (NT).

STUDY DESIGN

In all, 72 fetuses with normal NT and 71 fetuses with NT >95th percentile were evaluated. NT size, jugular lymphatic sacs (JLS), jugular vein and ductus venosus pulsatility index for veins (PIV), and intracardiac velocities were measured.

RESULTS

JLS were visualized in 22/72 fetuses with normal and in 55/71 fetuses with increased NT. Jugular vein and ductus venosus PIV was higher in fetuses with increased NT compared to normal NT (P < .01). Visibility of JLS was associated with a higher ductus venous PIV (P < .05), but not with a higher jugular vein PIV. Larger NT and larger JLS volumes were associated with higher jugular vein and ductus venosus PIV (P < .05).

CONCLUSION

This study shows a relation among increased NT, jugular lymphatic distension, and altered blood flow in jugular vein and ductus venosus.

Lymphatic capillary hypoplasia in the skin of fetuses with increased nuchal translucency and Turner's syndrome: comparison with trisomies and controls

Fetuses with Turner's syndrome or trisomies 21, 18 and 13 show excess of skin, which can be visualized by ultrasonography as increased nuchal translucency at 11-13(+6) weeks' gestation. The objective of this study was to gain insight in the development and distribution of blood vessels, lymphatic capillaries of the cutis and lymphatic collectors of the cutis and subcutis and to study developmental changes with increasing gestation. Immunofluorescence of cryosections with 10 specific antibodies was used to investigate the nuchal skin of three fetuses with Turner syndrome's and to differentiate lymphatics, lymph capillaries (FLT4, PTN 63, LYVE1, PROX1), blood vessels (KDR, CD 31, PDPN), blood clotting activity (von Willebrand factor), basement membranes and big vessels (Laminin, Collagen Type IV). The findings were compared with those in seven fetuses with trisomy 21 and two fetuses each with trisomies 18 or 13, respectively, as well as six normal controls. Immunoreactive receptors for vascular endothelial growth factors (FLT4) were decreased in lymphatic capillaries of the skin of Turner fetuses. Accordingly, LYVE1 was scarce and PROX1 staining was less intense in the dermis of Turner fetuses. Lymphatic collectors were, however, evenly stained. In normal fetuses and in those with trisomies, lymphatic capillaries were evenly distributed. We conclude that lymphatic capillary hypoplasia might be responsible for nuchal cystic hygroma in Turner syndrome. The biological basis for increased nuchal translucency in trisomies may however be different.

Abnormal Shh and FOXC2 expression correlates with aberrant lymphatic development in human fetuses with increased nuchal translucency

OBJECTIVE

Previous research in fetuses with increased nuchal translucency (NT) showed abnormal lymphatic endothelial differentiation characteristics, including increased vascular endothelial growth factor (VEGF)-A expression, and aberrant smooth muscle cells (SMCs) surrounding enlarged jugular lymphatic sacs (JLS). We hypothesized that abnormal Sonic hedgehog (Shh) expression would result in altered VEGF-A signaling in the lymphatic endothelial cells of the JLS and that aberrant acquisition of SMCs could be caused by downregulation of forkhead transcription factor FOXC2 and upregulation of platelet-derived growth factor (PDGF)-B in the lymphatic endothelial cells of the JLS.

METHODS

Five trisomy 21 fetuses and four controls were investigated using immunohistochemistry for Shh, VEGF-A, FOXC2 and PDGF-B expression in the lymphatic endothelial cells of the JLS.

RESULTS

An increased Shh, VEGF-A and PDGF-B expression, and decreased FOXC2 expression were shown in the lymphatic endothelial cells of the JLS of the trisomic fetuses.

CONCLUSIONS

Increased Shh and VEGF-A expression is correlated with an aberrant lymphatic endothelial differentiation in trisomy 21 fetuses. The SMCs surrounding the JLS can possibly be explained by an increase of PDGF-B-induced SMC recruitment and/or differentiation. This underscores earlier findings that indicate the loss of lymphatic identity in trisomy 21 fetuses and a shift towards a blood vessel wall phenotype.

Male gender as a favorable prognostic factor in pregnancies with enlarged nuchal translucency

OBJECTIVE

The aim of this study was to investigate the influence of fetal gender on pregnancy outcome in fetuses with enlarged nuchal translucency (NT).

METHODS

Pregnancy outcomes of all women who underwent an NT measurement at our institution between January 2000 and November 2007 were retrospectively reviewed. Separate analyses were performed for fetuses with normal and with enlarged (>or= 95(th) percentile) NT.

RESULTS

A normal NT was measured in 3637 males (51.4%) and 3435 females (48.6%). Of the fetuses with enlarged NT 365 were males (57.4%) and 271 females (42.6%) (P = 0.001). In this group a normal pregnancy outcome-of those pregnancies for which the outcome was known-was registered for 187/332 (56.3%) of the male fetuses and 98/249 (39.4%) of the female fetuses (P < 0.001; relative risk (RR) for adverse outcome for male gender, 0.72). Eighty percent of the chromosomally normal male fetuses with an enlarged NT had an uneventful pregnancy outcome; this increased to 90% when only the male fetuses with NT measurements >or= 95(th) percentile and < 99(th) percentile and normal karyotype were considered (RR for adverse outcome for male gender, 0.47).

CONCLUSION

In a population of fetuses with enlarged NT there are significantly more males. Male fetuses with enlarged NT and normal chromosomes have an almost two-fold greater chance of a favorable outcome than females. We believe that a minimal degree of NT enlargement in male fetuses without genetic or structural anomalies may be interpreted as a feature of accelerated growth or, alternatively, as a maturational delay of the cardiovascular system more common in males, leading to moderately increased nuchal fluid accumulation.

Jugular lymphatic sacs in first-trimester fetuses with normal nuchal translucency

OBJECTIVE

To assess the ultrasonographic appearance of the jugular lymphatic sacs (JLS) in first-trimester fetuses with a normal nuchal translucency (NT).

METHODS

Seventy-five fetuses with a normal NT thickness (< 95(th) percentile) were examined weekly between 11 and 17 weeks of gestation. After measurement of the NT thickness, the neck region was examined using both transvaginal and transabdominal ultrasonography for the presence of JLS. If present, their dimensions were measured in three directions and the volume was calculated using the formula for a spheroid. Data were analyzed using multilevel analysis.

RESULTS

Seventy-five fetuses were evaluated and a total of 243 ultrasound examinations of the neck region were performed. In 25 (33%) of the 75 fetuses, the JLS could be observed once or more than once. In 19 fetuses JLS were visualized once, in five fetuses twice and in one fetus three times. In total, the JLS were visualized 32 times (n = 15 bilaterally, n = 15 only the left JLS and n = 2 only the right JLS). Relatively greater NT thickness was associated with a higher probability of the presence of JLS, although this was not statistically significant (NT < 1 mm, probability 0.07; NT 1-2 mm, probability 0.15, P = 0.10; NT > 2 mm, probability 0.20, P = 0.08). Gestational age was predictive for the presence of JLS, with the highest probability between 13 and 15 weeks of gestation (P < 0.01). No relationship was found between gestational age and the volumes of the left and right JLS.

CONCLUSION

The JLS can be visualized on ultrasound examination in a significant proportion of fetuses with normal NT, most often between 13 and 15 weeks of gestation, and this does not seem to be associated with any abnormality in these fetuses.

Jugular lymphatic sacs in the first trimester of pregnancy: the prevalence and the potential value in screening for chromosomal abnormalities

OBJECTIVE

To investigate the prevalence of detectable jugular lymphatic sacs in a setting for first trimester screening for Down syndrome, and to evaluate the influence of jugular lymphatic sacs on the screening performance for chromosomal abnormalities.

METHODS

A prospective single center study (Erasmus University Medical Center, Rotterdam, The Netherlands) over a period of one year (January 2003-February 2004). First trimester nuchal translucency measurement was performed in a study population of 415 fetuses. Additionally, the transversal plane with the spine and mandible was visualized to verify the presence of jugular lymphatic sacs. The jugular lymphatic sacs were measured anterior-posterior. The association between nuchal translucency and jugular lymphatic sacs was tested.

RESULTS

Follow-up was complete in 406 cases (97.8%). Jugular lymphatic sacs could be visualized in 98 out of 415 (23.5%). The nuchal translucency thickness and the mean of the left and right jugular lymphatic sac were significantly correlated.

CONCLUSION

The sonographic visualization of jugular lymphatic sacs significantly predicts chromosomal abnormalities, although nuchal translucency is a better predictor. Nuchal translucency and jugular lymphatic sacs are strongly correlated and therefore not applicable in a combination test.

Nuchal Translucency and First Trimester Risk Assessment

First-trimester risk assessment for fetal aneuploidy using nuchal translucency (NT) measurement is rapidly gaining popularity in the United States. In combination with maternal serum markers in the first trimester, the screening performance is exceptionally good, with detection rates of more than 80% at a screen positive rate of 5%. Recently, the method has been validated for screening for Down syndrome and other aneuploidies in multicenter trials in the United States and elsewhere. Compliance with established criteria for measurement of the NT is essential to achieve uniform reliability and high screening test sensitivity. There is an international consensus about the importance of specific training in the NT examination, conformity to standards of NT measurement, and regular audit for quality assurance. In the United States, the Nuchal Translucency Quality Review program has been developed to administer credentialing and quality review for registered practitioners. The Nuchal Translucency Quality Review credentials signify the proficiency of the sonographer or sonologist in NT measurement and participation in a regular quality assurance audit. We encourage accreditation of clinical sites offering first-trimester risk assessment to ensure the highest quality care.