Hannelore T. Loevy

Discordant monozygotic twins with trisomy 13

Monozygotic twins with typical trisomy 13 are reported. Despite an identical karyotype, the twins were dimorphic for the presence of an omphalocele. Reasons for the rarity of MZ twins with trisomy 13 are presented. It is suggested that the presence of a chromosomal abnormality in MZ twins may predispose to dimorphism.

Lithium Ion in Cleft Palate Teratogenesis in CD1 Mice

Summary The teratogenic effects of lithium on CD1 mice were studied. A dose of 15.5 mg of lithium chloride monohydrate in sterile water (Injection U.S.P.) was given each day for 2 or 3 days on days 11 through 13 of pregnancy. The mice were sacrificed on day 17 of pregnancy. The uteri were examined for resorption sites and the fetuses for malformations. The incidence of cleft palate in the offspring of mice injected on days 11, 12, and 13 was 15.1%; on days 12 and 13, 7.2%; and on days 11 and 12, 3.4%. Since the incidence of spontaneous cleft palate is very low in these mice, a teratogenic effect of lithium salts has been demonstrated. There was also an increase in resorption sites. The pregnant mothers did not show any evident ill effects from the lithium salt at the dosage given. The able technical assistance of Mrs. M. A. Wade and Messrs. G. Businaro and W. A. Stammer is gratefully acknowledged.

Cortisone-Induced Teratogenic Effects in Mice

Summary Four consecutive daily doses of cortisone on days 11 through 14 of pregnancy were injected into several strains of mice and their hybrids and the incidence of cleft palate noted in the offspring. In Strong A mice the incidence of induced cleft palate was 100% compared to 9% of spontaneous cleft palate. In C3H mice, the incidence of induced cleft palate was 36% compared to less than 1% of spontaneous cleft palate. In the BALB/c the incidence of induced cleft palate was 62% and no cases of spontaneous cleft palate were noticed. The incidence varied greatly in the hybrids and backcrossings according to the genetic pattern of the fetuses. Of particular interest is the backcrossing of A × BALB/c females to A males with an incidence of 92% of cortisone-induced cleft palate, which may be useful as a pharmacogenetic tool in studying drug-induced orofacial malformations.

Lack of Difference in Sex Ratio of Mice with Cortisone-Induced Cleft Palate

Cortisone injected into pregnant CD1 and Strong A mice increased the number of resorption sites but had no statistically significant effect on the sex ratio of the surviving fetuses. With one exception, no difference between sexes in incidence of cleft palate was demonstrated, which suggests that cortisone in the dose used did not induce cleft palate through a sex-dependent mechanism.

Cytogenetic Analysis of Siamese Cats with Cleft Palate

Chromosomes of the bone marrow cells of three Siamese kittens with cleft palate and one normal kitten were examined. The pedigrees of all the abnormal kittens were examined and common ancestry was demonstrated. No numerical or morphologic difference in the autosomes was found in the kittens with cleft palate or the normal kittens.

Serum Proteins and Glycoproteins in 2 Strains of Mice Differing in Teratogenic Potential.

Summary In 2 strains of mice, Strong A and C3H, which are respectively susceptible and resistant to induction of cleft palate in offspring when cortisone is given to pregnant mothers, it was found that cortisone, pregnancy per se and pregnancy plus cortisone lead to definite and different effects on serum proteins, protein fractions, and protein-bound carbohydrate fractions. A direct connection between protein metabolism and cleft palate is not inferred from the results.

Follow-Up Studies of Cortisone Teratogenicity in CD1 Strain Mice

Female newborns of cortisone-injected CD, strain of mice were mated to siblings, were then injected during pregnancy with 5 mg of cortisone on either the 11 th or the 12th day of gestation, and were killed one day after delivery. The incidence of induced cleft palate was as high as the incidence of cortisone-induced cleft palate previously reported for this strain.