Congenital absence of the heart: observation of human funiculopagous twinning with insertio funiculi furcata, fusion, forking, and interpositio velamentosa

Klinefelter twins presenting with discordant aneuploidies, acardia, forked umbilical cord and with different gonadal sex despite monozygosity

OBJECTIVE

A higher frequency of twin births in sibships of Klinefelter syndrome patients and also monozygotic or dizygotic twins, themselves being affected by Klinefelter syndrome have been noted repeatedly. To address this issue, we evaluated type and frequency of twinning among Klinefelter fetuses that we had received for autopsy within a 'Prenatal Diagnosis' program.

METHOD

We performed fetal autopsies, and genetic analyses on DNA extracted from stained histological slides.

RESULTS

Among 41 prenatal diagnoses of a 47, XXY karyotype we observed four twin pairs. One was dizygotic with discordant Klinefelter and Down syndrome. Three twin pairs were monozygotic as concluded from monochorial placentation. In two monozygotic pairs one twin partner was an acardiac monster and in one of these the acardiac twin showed a female gonadal sex and missing Y-chromosomal SRY-sequences as confirmed by polymerase chain reaction.

CONCLUSIONS

There is a high rate of twinning and twin reversed arterial perfusion sequence among our Klinefelter fetuses. Forked umbilical cords at the placental insertion site in one case allowed classification as conjoined twins in the sense of a 'funiculopagus'. Anaphase lagging or semidizygosity by second polar body twinning are proposed as explanations for the gonadal sex discordance and the excessive developmental disadvantage in the one acardiac. Problems may arise with regard to non-invasive prenatal diagnosis of aneuploidies in twin pregnancies.

Acardia: predictive risk factors for the co-twin's survival

This study aimed to find factors in acardiac pregnancies that could be used to predict survival rates of the pump fetus. Five cases of acardia at Monash Medical Centre were found, and all case reports available in the literature from 1960 to 1991 (184 cases) were collected and analyzed. Acardia is more common in nulliparous women and in monoamniotic monochorionic pregnancy. The acardiac fetus usually has a two-vessel umbilical cord and is most likely to develop structures supplied by the lower aortic branches. Delivery is more often preterm (mean gestation = 31.1 weeks) than normal twins. The overall perinatal mortality for the pump fetus is 35% in twins and 45% in triplets. Factors associated with a statistically significant increase in perinatal mortality for the pump fetus include delivery before 32 weeks gestation, acardiacus anceps form of acardia, and the presence of arms, ears, larynx, trachea, pancreas, kidney, or small intestine in the acardiac fetus. Active intervention in these pregnancies is reasonable.

Acardiac fetus in a triplet pregnancy

The acardiac monster represents one of the most severe but rare congenital anomalies. It occurs only in multiple gestations associated with vascular anastomoses between the affected fetus and its co-twin. The prenatal diagnosis of an acardiac fetus must be suspected in any multiple gestation in which cardiac activity cannot be documented sonographically in a growing fetus. We report an acardiac fetus occurring in a spontaneously conceived triplet pregnancy. A review of the literature, including pathogenetic theories and sonographic reports, is discussed.

The holoacardius: a correlative computerized tomographic, radiologic, and ultrasonographic investigation of a new case with review of literature

A holoacardius from a monozygotic, monochorionic twin pregnancy of 36 weeks is described. Trisomy-18 was diagnosed in the viable female cotwin. Computerized tomographic, radiologic, and ultrasonographic procedures were applied to the acardiac. Its three-vessel umbilical cord was velamentously attached to the single placenta. Grossly malformed and poorly developed craniofacial structures, absence of neck and upper extremities, sirenomelic lower extremity, absence of heart, and development of only a few skeletal elements were prominent features. A review of selected world literature emphasizes the limits of the estimates dealing with the total number of reported cases and the incidence of acardii.

Muscle abnormalities associated with the twin reversed-arterial-perfusion (TRAP) sequence (acardia)

Even though over 400 acardia (twin reversed-arterial-perfusion, TRAP) specimens have been reported in the literature since 1533, few attempts have been made to provide detailed evaluation of anything other than the circulation. The purpose of this study was to evaluate the various limb defects in nine TRAP specimens in light of the presumed etiology and pathogenesis, reversed arterial perfusion, and subsequent degenerative changes in the fetus. Two hypotheses were tested: (1) degeneration of formed tissues should not result in tissue rearrangement and (2) one tissue type should be lost in preference to the others. Neither of these hypotheses were supported by the data. Alternative explanations are discussed as well as the implications of these observations on the concept of reversed arterial perfusion.

The acardiac anomaly new case reports and current status

Two cases of holoacardius are presented. Both had a normal 46,XX female karyotype, identical to that of their respective cotwin. Data are presented supporting the concept that the placental vascular anastomoses are the primary agents in the formation of an acardiac. Cytogenetics, epidemiology and other theories of pathogenesis are discussed.