Cytomegalovirus infection in a newborn dizygous twin

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.

Prenatal diagnosis and outcome of congenital cytomegalovirus infection in twin pregnancies

OBJECTIVE

To study the outcome of 20 twin pregnancies with evidence of primary or recurrent cytomegalovirus (CMV) infection during pregnancy.

DESIGN

Observational study.

SETTING

Two tertiary perinatal departments in Israel.

POPULATION

Twenty women with twin pregnancies who were referred because of serologic investigation indicating CMV infection. Seventeen women had evidence of primary CMV infection, and three women appeared to have recurrent CMV infection.

METHODS

Prenatal diagnosis was made by amniocentesis of both sacs after 21 weeks of gestation. CMV isolation was performed by culture on fibroblasts, shell vial technique and polymerase chain reaction (PCR) amplification of CMV DNA. After birth, the neonatal urine and saliva were cultured for CMV.

MAIN OUTCOME MEASURES

Intrauterine CMV infection defined as positive PCR at amniotic fluid analysis and congenital CMV infection defined as positive CMV cultures after birth.

RESULTS

Except for one, all women underwent amniocentesis of both gestational sacs. In 14 (70%) women, no evidence of vertical transmission to any of the 28 fetuses was found and none of the newborns had evidence of congenital CMV infection. Intrauterine infection was detected by amniocentesis in five women and by ultrasound findings with positive maternal serology in one. In three women, CMV was detected in only one amniotic sac. In five of our six total cases, both twins were found to have congenital CMV infection at birth, all of whom had dichorionic-diamniotic placentation, three fused and two separate.

CONCLUSIONS

In twin gestations, as in singletons, intrauterine and congenital CMV infection occurs in about 30% of women with primary or recurrent infection. The placenta type did not predict if one or both twins would be infected. Our data do not exclude the possibility that intrauterine transmission of the virus from one fetus to the other can occur.

High risk of HIV-1 infection for first-born twins. The International Registry of HIV-exposed Twins

To examine the epidemiology and natural history of mother-to-infant transmission of human immunodeficiency virus type 1 (HIV-1), especially genetic and intrapartum exposure factors, we obtained data on twins and triplets born to women infected with the virus. 40 investigators in nine countries contributed demographic, clinical, and epidemiological data on 100 sets of twins and 1 set of triplets. Among the 66 evaluable sets, HIV-1 infection was more common in first-born than in second-born twins (p = 0.004). In 22 sets, only one twin was infected (18 first-born, 4 second-born). 50% of first-born twins delivered vaginally and 38% of first-born twins delivered by caesarean were infected, compared with 19% of second-born twins delivered by either route. HIV-1 infection status tended to be concordant in more monozygotic (14 of 17 sets) than dizygotic (26 of 43) sets, but the frequency and clinical signs of HIV-1-related disease were similar in only 3 of the 10 sets with both children infected. These findings suggest that some infants may be infected in utero before labour but that a substantial proportion of HIV-1 transmission occurs as the first twin encounters the cervix and birth canal. Such measures as cleansing of the birth canal and caesarean delivery before membrane rupture might reduce the risk of transmission for infants born to HIV-1-infected women and should be the subjects of controlled clinical trials. Caesarean section should not be regarded as a wholly preventive measure, however, since substantial proportions of both first-born and second-born twins delivered in this way were infected.

On the unpredictable development of congenital cytomegalovirus infection. A study in twins

Two cases of congenital cytomegalovirus (CMV) infection in twins are reported. In addition, congenital CMV infection in twin pairs described in the literature is reviewed. The relationship of monochorionic vs. dichorionic placentas and monozygosity vs. dizygosity in the development of congenital infection in either one or both members in a pair of twins is discussed.

Congenital focal glomerular lesions in only one monozygotic twin related to a probable twin transfusion syndrome

A case of congenital focal glomerular lesions involving crescent formation in only one monozygotic twin is reported. The possible effect of chronic hypotension in the pathogenesis of the lesion is discussed, considering the fact that the affected twin was probably the donor in a feto-fetal transfusion syndrome.

Serum immunoglobulins in multiple pregnancy

The concentrations of immunoglobulins (Ig) G.A.M. and E were determined in paired umbilical cord and maternal sera in 50 twin pregnancies. Mean IgG levels were higher in cord than maternal sera and in most cases the cord IgG level related more closely to that of the other twin than to either maternal level or birthweight, and was in the range for singletons of the same gestational age. The three cases of fetofetal transfusion syndrome were exceptional in the large difference between IgG concentrations in recipient and donor twins. The discrepancy was much greater than that found between the levels of proteins produced by the fetus, suggesting a disturbance in maternofetal placental transfer. IgM was detected in all cord sera, with one exception, and the level was not related to order of birth. IgA was detected in 16% of cord sera, 13% in sera from first borns. IgE was detected in only 8% of cord sera and there was no evidence of placental transfer.