Congenital Cytomegalovirus Infection in Monozygotic Twins with Twin-to-twin Transfusion Syndrome

Congenital Cytomegalovirus Infection and Hearing Outcomes in Twins: A Systematic Review of Reported Cases

OBJECTIVE

Congenital cytomegalovirus infection is the leading nonhereditary cause of pediatric sensorineural hearing loss. This systematic review evaluated infection concordance and comparative hearing abilities in twins/multiple births to model infection patterns.

DATABASES REVIEWED

PubMed, Embase, Web of Science, and Google Scholar.

METHODS

Studies that reported hearing outcomes of congenital cytomegalovirus infection in at least one multiple birth were eligible. Concordant infections (both twins) and discordant infections (single twin) were included. Multiple reviewers performed data extraction and quality assessment. Analyses involved relative risk of infection concordance by zygosity and chorionicity and odds of hearing loss by infection concordance. Hearing outcomes were compared between siblings.

RESULTS

Of 247 studies screened, 31 were included (74.2% high quality). The review captured 40 eligible multiple births. Among infected patients, 42.9% (95% confidence interval, 31.2-55.2%) demonstrated hearing loss. All uninfected twins had normal hearing. Most infections were concordant, and infected patients experienced 4.11 (1.18-14.36) times greater odds of hearing loss if their twin was also infected ( p = .02). Yet siblings' hearing outcomes diverged in over 40% of concordant cases. If either twin is infected, infection risk in the second twin is 3.25 (1.83-5.79) times greater in monozygotic than dizygotic twins and 2.50 (1.61-3.88) times greater in monochorionic than dichorionic twins (both p < .001). We describe a case from our practice.

CONCLUSION

Congenital cytomegalovirus infection patterns and hearing outcomes can vary widely even within a shared fetal and postnatal environment. Suspected infection in a twin indicates that both should receive testing and continued monitoring for late-onset sequelae.

Differential congenital cytomegalovirus infection in dichorionic diamniotic twins—A case report and literature review

Background

Cases of differential congenital cytomegalovirus (CMV) infection in twins are rarely reported. The chance of congenital infection and the clinical outcome of monochorionic diamniotic or dichorionic diamniotic twins are highly uncertain.

Cases presentation

We reported a case of differential congenital CMV infection in dichorionic diamniotic twins. Despite being exposed to the same maternal environment and similar genetic background, twins reacted differently to maternal infection and presented with non-concordant infection status. The potential mechanism of discordant infection from aspects of type of chorion and placenta and immune status has been discussed through literature review.

Conclusion

CMV infection can present as differential congenital infection in twin pregnancy, with various clinical symptoms. Fetal cellular immune function may be involved in the pathogenesis.

Vertical Transmission and Discordance of Cytomegalovirus in Twin Pregnancies

Objective

The objectives are to estimate the vertical transmission rate in twins relative to singleton pregnancies, to evaluate whether discordance within twin pairs is rare, and to characterize concordance within monozygotic and dizygotic twin pairs in relation to hereditability.

Methods

We first sought to estimate the vertical transmission rate of congenital CMV infection in twins by gathering cohort-based studies of congenital CMV in which vertical transmission in both singleton and twin pregnancies was reported. This also allowed us to compare singleton and twin infection rates. From the above studies and other large cohorts of congenitally infected infants, the percentage of discordantly infected twin pairs determined whether this is a rare phenomenon. Theorizing discordance is not rare, we then analyzed data from cases with twin outcomes for congenital CMV infection, according to whether the twins were monozygotic or dizygotic, and calculated their corresponding concordance rates to estimate the broad-sense heritability. Lastly, we described other factors that might affect vertical transmission.

Results

From five articles following at-risk pregnancies, the rate of vertical transmission in twin pregnancies is 58.7% (95% CI 43.3-72.3%) whereas in singleton pregnancies it is 31.4% (95% CI: 29.0-34.0%) p = 0.0002. Of ten studies of larger cohorts of infants with congenital CMV infection, 21 of 42 twin pairs with at least one twin infected were discordant for congenital CMV (50.0%, 95% CI: 34.4–65.6%) indicating discordance of congenital CMV infection in twin pairs is not rare. Of 28 studies covering 37 twin pairs where at least one twin had congenital CMV, and zygosity was known, eleven of thirteen monozygotic twin pairs (84.6%; 95% CI: 53.7-97.3%) were concordant for CMV infection, and nine of twenty-four dizygotic twin pairs (37.5%; 95% CI: 19.6-59.2%) were concordant for infection giving an estimated hereditability of 94.2%. Within these 37 twin pairs, factors such as primary or recurrent maternal infection, prematurity, growth discordance, and sex are described; however, in many of these cases these factors are unknown.

Conclusion

The rate of vertical transmission of congenital CMV is higher for twins than singletons. Discordance of congenital CMV in twins is not rare and suggests a possible genetic susceptibility to congenital CMV.

Congenital Cytomegalovirus Infection After a Multiple Birth Pregnancy

BACKGROUND

Congenital cytomegalovirus (cCMV) infection is an important cause of hearing loss and neurodevelopment delay. While data on vertical transmission and neonatal outcome after singleton pregnancy with cCMV are well established, only scarce reports have addressed cCMV in multiple birth pregnancies. Furthermore, no studies have yet compared the outcome after birth and long-term follow-up of children with cCMV born after a singleton versus multiple pregnancies.

METHODS

Infant outcome after birth of symptomatic versus asymptomatic infection was compared for infants born with cCMV after multiple (study group) and singleton (control group) pregnancies in a 1:2 ratio.

RESULTS

Of 508 infants diagnosed with cCMV, 25 (4.9%) were born after a multiple pregnancy. Children in the study and control groups did not differ in terms of specific prenatal CMV investigations including amniocentesis and brain magnetic resonance imaging studies. However, prematurity rates were significantly higher in the study compared with control group (52% vs. 4%, P < 0.001). There was a higher rate of symptomatic cCMV infection in the study group than in the controls (48% vs. 14%, P < 0.001). Hearing impairment at birth was also more frequent in the study group (32% vs. 8%, P = 0.016). A long-term follow-up demonstrated that children in the study group had higher rates of neurologic sequelae (hearing impairment or neurodevelopmental delay) compared with children in the control group (20% vs. 4%, P = 0.016).

CONCLUSIONS

Infants with cCMV born after multiple birth pregnancies are born earlier and have a higher risk of symptomatic disease at birth and worse long-term neurologic outcome than those born after a singleton pregnancy. This important group of children warrants meticulous prenatal and postnatal care.