Exomphalos and trisomy 18 syndrome. Report of two cases

Umbilical cord pseudocyst in trisomy 18

Prenatal diagnosis of cord defects by means of ultrasound examination is possible and highly accurate. Although this is a rare pathological finding, we report two cases in which umbilical cord pseudocysts were associated with trisomy 18. These observations underscore the need of umbilical blood sampling for establishing the karyotype in fetuses with such umbilical cord anomalies and the importance of careful examination of placentas and infants born with such defects.

Neural tube defects and omphalocele in trisomy 18

A trisomy 18 fetus with severe congenital anomalies including craniorachischisis, large omphalocele, and bilateral cleft lip and palate is reported. The occurrence of neural tube defects and/or omphalocele in reported cases of trisomy 18 is discussed and the frequency of these anomalies in 85 trisomy 18 patients evaluated at Indiana University School of Medicine from 1963 to 1986 is reviewed. In this series of patients the frequency of neural tube defects was 7.0% and the frequency of omphaloceles was 5.9%. The percentage of these findings in our cases supports the premise that neural tube defects and omphaloceles are part of the trisomy 18 phenotype. Since fetuses with trisomy 18 are subject to early fetal loss or premature birth, the more subtle physical features of this condition may not be apparent. Thus, karyotyping of fetuses and premature infants with either neural tube defect or omphalocele should be considered.

Omphalocele and partial trisomy 1q syndrome

A male infant with partial trisomy 1q syndrome (46,XY,der(21),t(1;21)(q25;q22)pat) is described. Clinical findings include small for gestational age, hypoglycemia, ocular hypertelorism, microphthalmia, coloboma of the iris, low-set ears, beak nose, micrognathia, micropenis, cryptorchidism, presacral dimple, flexion contractures of the fingers, bifid thumb, Simian crease, and overriding toes. In addition, he had a large omphalocele not previously seen in trisomy 1q. Postmortem findings include underdeveloped cerebellum, a thymus with moderate depletion of thymocytes, a large PDA, ASD, small adrenal, and fatty change of the liver. The grandfather, father, and a male sibling have translocation t(1;21)(q25;q22). A family history of repeated spontaneous abortions is present.