Persistent right umbilical vein in a fetus with Noonan's syndrome: a case report

Extending the prenatal Noonan's phenotype by review of ultrasound and autopsy data

OBJECTIVES

The antenatal phenotypic spectrum of Noonan Syndrome (NS) requires better characterization.

METHODS

This multicenter retrospective observational included 16 fetuses with molecularly confirmed NS admitted for fetopathological examination between 2009 and 2016.

RESULTS

Among 12 pathogenic variants (PV) in PTPN11 (80%), 5 (42%) fell between position c.179 and c.182. Ultrasound showed increased nuchal translucency (n=13/16, 93%), increased nuchal fold after 15 weeks of gestation (n=12/16, 75%), pleural effusions (n=11/16, 69%), polyhydramnios (n=9/16, 56%), hydrops (n=7/16, 44%), cardiovascular (n=6/16, 38%) and cerebral (n=4/16, 25%) anomalies. Fetopathological examination found dysmorphic features in all cases, cardiovascular anomalies (n=12/15, 80%), pulmonary hypoplasia (n=10/15, 67%), effusions (n=7/15, 47%) and neuropathological anomalies (n=5/15, 33%). Hydrops was significantly (p=0.02) more frequent in the four fetuses with RIT1, NRAS and RAF1 PV versus the 12 fetuses with PTPN11 PV.

CONCLUSIONS

Increased nuchal translucency and nuchal fold is common in NS. NS antenatal phenotype showed high in utero fetal death, hydrops, prenatal pleural effusion and pulmonary hypoplasia, although the inclusion of only deceased fetuses will have selected more severe phenotypes. Non-specific cardiovascular and neurological abnormalities should be added to NS antenatal phenotype. Next generation sequencing will help detect more genotypes, clarifying the prenatal phenotype and identifying genotype-phenotype correlations. This article is protected by copyright. All rights reserved.

Ultrasonic detection of fetal persistent right umbilical vein and incidence and significance of concomitant anomalies

BACKGROUND

Persistent right umbilical vein (PRUV) is characterized by atresia of the left umbilical vein while the right umbilical vein remains open. Given the limited sample size of most studies, the incidence of PRUV and the status of concomitant anomalies may not be fully reflected. Thus, we studied the incidence of fetal PRUV and its concomitant anomalies on a larger scale using our hospital database. This study hoped to address the following questions: Does PRUV increase the risk of fetal anomalies? If the PRUV fetus also has a single umbilical artery (SUA), does the risk of fetal anomaly increase further? What is the positive predictive value of PRUV for fetal anomalies?

METHODS

This retrospective study analyzed 756 cases of fetal PRUV at our hospital from January 2007 to April 2017. Prenatal ultrasound and color Doppler images were assessed. All PRUV fetuses underwent echocardiography and detailed ultrasound examinations of other systems. Newborn status was obtained via the database or by telephone follow-up.

RESULTS

A total of 435,428 pregnant women underwent prenatal ultrasonography at 16-40 weeks, the incidence of fetal PRUV was 0.17%, and 102 fetuses (13.5%) developed other anomalies. Two complicated cases had trisomy 18. PRUV was associated with a higher incidence of fetal anomalies. When fetal anomalies were classified by body systems, PRUV was associated with a higher incidence of cardiovascular, nervous, urinary, skeletal, digestive, and respiratory system anomalies. The positive predictive values of a PRUV for any fetal anomalies and cardiovascular anomalies were 13.5% (95%CI, 11.2-16.2%) and 5.4% (95%CI, 4.0-7.3%), respectively. SUA further increases the risk of PRUV fetuses with other anomalies and cardiovascular anomalies.

CONCLUSIONS

Detailed prenatal ultrasonography and echocardiography should be performed in fetuses with PRUV to rule out anomalies in other systems. When the PRUV is combined with SUA, echocardiography is particularly important. Fetuses with complicated PRUV should undergo chromosomal examination. Although isolated fetal PRUV prognosis is good, complicated PRUV prognosis depends on the type and severity of the concomitant anomalies.

Clinical and functional characterization of a novel RASopathy-causing SHOC2 mutation associated with prenatal-onset hypertrophic cardiomyopathy

SHOC2 is a scaffold protein mediating RAS-promoted activation of mitogen-activated protein kinase (MAPK) signaling in response to extracellular stimuli. A recurrent activating mutation in SHOC2 (p.Ser2Gly) causes Mazzanti syndrome, a RASopathy characterized by features resembling Noonan syndrome and distinctive ectodermal abnormalities. A second mutation (p.Met173Ile) supposed to cause loss-of-function was more recently identified in two individuals with milder phenotypes. Here, we report on the third RASopathy-causing SHOC2 mutation (c.807_808delinsTT, p.Gln269_His270delinsHisTyr), which was found associated with prenatal-onset hypertrophic cardiomyopathy. Structural analyses indicated a possible impact of the mutation on the relative orientation of the two SHOC2's leucine-rich repeat domains. Functional studies provided evidence of its activating role, revealing enhanced binding of the mutant protein to MRAS and PPP1CB, and increased signaling through the MAPK cascade. Differing from SHOC2 ^S2G , SHOC2 ^{Q269_H270delinsHY} is not constitutively targeted to the plasma membrane. These data document that diverse mechanisms in SHOC2 functional dysregulation converge toward MAPK signaling upregulation.

Prenatal diagnosis of persistent right umbilical vein - Incidence and clinical impact. A prospective study

Background

Persistent right umbilical vein (PRUV) is usually an isolated finding but it may be accompanied by other fetal malformations.

Aims

We aimed to determine the incidence of prenatally diagnosed PRUV in a referral population, assess the neonatal outcome and discuss the findings together with those from previous publications.

Materials and methods

A total of 2360 women with low‐risk singleton pregnancies were examined in the second and third trimesters. A transabdominal convex volume transducer was used. B‐mode was applied in each patient. Scanning of the venous system included imaging of the target vessels with two‐dimensional colour Doppler mapping. The diagnosis of PRUV was made in a transverse section of the fetal abdomen. Three‐dimensional ultrasounds were performed as necessary, when anomalous cases were encountered.

Results

The incidence of PRUV in our population was 12/2360 = 0.5%, and it was higher than in other retrospective studies. In 75% (n = 9), PRUV was an isolated finding where delivery was uneventful and the postnatal outcome was favourable. In two cases PRUV was accompanied by omphalocele, and in one case by tetralogy of Fallot and single umbilical artery.

Conclusions

PRUV is an uncommon prenatal finding. Screening for this anomaly can be easily performed in all pregnant patients. A diagnosis of PRUV should be followed by a thorough fetal morphology scan in order to exclude any other malformations, especially those of the cardiovascular system.

Prenatal and Postnatal Sonographic Confirmation of Congenital Absence of the Ductus Venosus in a Child with Noonan Syndrome

The ductus venosus serves as an important vascular pathway for intrauterine circulation. This case presents a description of an absent ductus venosus in a female patient with Noonan syndrome, including both prenatal and postnatal imaging of the anomaly. In the setting of the anomalous vascular connection, the umbilical vein courses inferiorly to the iliac vein in parallel configuration with the umbilical artery. This finding was suspected based on prenatal imaging and the case was brought to attention when placement of an umbilical catheter was thought to be malpositioned given its appearance on radiography. Ultrasound imaging confirmed the anomalous course. This is in keeping with prior descriptions in the literature of an association between Noonan syndrome and aberrant umbilical venous drainage. This case illustrates the need for awareness of this condition by the radiologist, allowing for identification on radiographs and the recommendation for further confirmatory imaging. Further, the case illustrates the value of paying particular attention to the fetal course of the umbilical vessels in patients with suspected Noonan syndrome, as this population is particularly at risk for anomalous vasculature.

Perinatal features of the RASopathies: Noonan syndrome, cardiofaciocutaneous syndrome and Costello syndrome

The RASopathies are a family of developmental disorders caused by heritable defects of the RAS/MAPK signaling pathway. While the postnatal presentation of this group of disorders is well known, the prenatal and neonatal findings are less widely recognized. We report on the perinatal presentation of 10 patients with Noonan syndrome (NS), nine with Cardiofaciocutaneous syndrome (CFCS) and three with Costello syndrome (CS), in conjunction with the results of a comprehensive literature review. The majority of perinatal findings in NS, CS, and CFCS are shared: polyhydramnios; prematurity; lymphatic dysplasia; macrosomia; relative macrocephaly; respiratory distress; hypotonia, as well as cardiac and renal anomalies. In contrast, fetal arrhythmia and neonatal hypoglycemia are relatively specific to CS. NS, CS, and CFCS should all be considered as a possible diagnosis in pregnancies with a normal karyotype and ultrasound findings of a RASopathy. Recognition of the common perinatal findings of these disorders should facilitate both their prenatal and neonatal diagnosis.

Persistent right umbilical vein: a prenatal condition worth mentioning?

OBJECTIVES

To investigate the incidence and clinical impact of prenatally diagnosed persistent right umbilical vein (PRUV) in a referral population and to evaluate the findings together with those from previous publications.

METHODS

This was a retrospective analysis of 39 cases with PRUV diagnosed in three tertiary referral centers for prenatal medicine between 1996 and 2009. Fetuses with situs inversus, situs ambiguous and heterotaxy (left and right isomerism) were excluded. During the study period 46 653 consecutive high- and low-risk pregnancies were examined. The prenatal sonograms and neonatal outcome data of affected individuals were reviewed. Our findings were analyzed together with findings retrieved from the scientific literature.

RESULTS

Twenty-nine fetuses had an isolated PRUV as a single anomaly, whereas 10/39 (25.6%) were found to have PRUV accompanied by additional minor and major abnormalities. These anomalies comprised mainly cardiovascular, genitourinary and gastrointestinal malformations. In common with our series, previously published cases of isolated PRUV (n = 197) displayed an uneventful course of pregnancy and a favorable postnatal outcome. Sixty-six previously reported cases of PRUV with additional anomalies were identified in the literature. Intrahepatic umbilical drainage is the most frequent type of PRUV. Including our cases, there were 16 cases (5.3%) with extrahepatic drainage of PRUV, all of which had additional anomalies.

CONCLUSIONS

Consistent with previous reports, in the majority of cases (74.8%) PRUV is an isolated finding. While these cases carry an excellent prognosis, PRUV can be associated with severe congenital anomalies, so this finding should prompt detailed prenatal assessment of the fetus.

Persistent Extrahepatic Right Umbilical Vein

Persistent right umbilical vein (PRUV) is a vascular pathology in which the left umbilical vein becomes occluded while the right umbilical vein persists and remains open. When observing fetal anatomy during a routine 18-week scan, it is important to notice the direction of the vasculature for possible fetal anomalies such as PRUV. In this case, a full detailed sonogram of the fetus was conducted and an extrahepatic PRUV was observed using 2D imaging and further confirmed using color Doppler to identify the type of PRUV. Following the identification of the PRUV, the fetus was thoroughly assessed for the possibility of other associated anomalies. Clearly, when an anomaly is observed, it is crucial to assess the fetus for associated congenital variances to identify risk and potential outcome.

Prenatal diagnosis of persistent right umbilical vein using three-dimensional sonography with power Doppler

OBJECTIVE

To investigate the incidence and the importance of isolated persistent right umbilical vein (PRUV) in our obstetric population and to determine the role of three-dimensional (3D) ultrasound in prenatal diagnosis of isolated PRUV.

MATERIAL AND METHODS

A total of 1,302 women who received regular antenatal care by a sole obstetrician at our hospital were prospectively evaluated between July 2003 and April 2005. Detailed anatomical evaluation of the fetus was performed by one sonographer. When the diagnosis of PRUV was made, it was confirmed by a senior obstetrician. 3D ultrasound with power Doppler was applied to delineate local anatomy. Echocardiography was performed in all the newborns by pediatric cardiologists to confirm the prenatal diagnosis and to evaluate for the presence of associated anomalies.

RESULTS

Six fetuses with PRUV were detected among the 1,302 study subjects. The incidence of PRUV in our population was 0.46% (1:217 live births). Vascular anatomy was easy to demonstrate using 3D power Doppler. The ductus venous (DV) was present in all six fetuses. An atrial septal defect was shown to exist in four newborns by neonatal echocardiography, but spontaneous closure had occurred in the follow-up scan.

CONCLUSION

PRUV is a common vascular anomaly that is easy to be overlooked. Reconstruction of the portal system in the affected fetuses using 3D ultrasound facilitated the identification of the DV. If the DV is present, and other anomalies are excluded, the fetus with PRUV has a good outcome.

Prenatal diagnosis of ductus venosus agenesis and its association with cytogenetic/congenital anomalies

OBJECTIVES

We present an observational study of 12 cases of anomalies of the umbilical and portal vein systems associated with absence of the ductus venosus (DV) diagnosed over the past 5 years. The hemodynamic implications of each pattern of umbilico-portal system anomalies associated with absence of the DV have been investigated, as well as the frequency and types of associated anomalies and their embryological origin.

METHODS

In all cases ultrasound, color Doppler, and cytogenetic investigations were performed.

RESULTS

Four main patterns of abnormal venous circulation were documented: (1). the umbilical vein (UV) bypasses the liver and drains into the right atrium directly or through a dilated coronary sinus (three cases); (2). the UV bypasses the liver, with an infrahepatic or suprahepatic connection directly to the inferior vena cava (IVC) (two cases); (3). the UV bypasses the liver and drains directly into the iliac or renal veins (four cases); and (4). the UV drains directly into the portal veins (three cases). Among seven cases with other associated anomalies (58%), there were three cases of Turner's and Noonan's syndromes. Two fetuses and two neonates died and there were two terminations of pregnancy (TOP).

CONCLUSIONS

In utero diagnosis of ultrasound patterns associated with DV anomalies is feasible. Fetal karyotyping should be considered, serial ultrasound examinations recommended and, in the presence of heart failure, delivery can be anticipated.