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Discordant severe cranial defects in monozygous twins
American Journal of Obstetrics and Gynecology
|June 1, 1975
Summary
This study reports three cases of monozygous male twins where one twin had severe developmental abnormalities like exencephaly, while the other was normal. Findings suggest environmental factors may contribute to these rare twin conditions.
Area of Science:
- Developmental biology
- Human genetics
- Teratology
Background:
- Monozygous twins can exhibit discordant phenotypes.
- Congenital abnormalities in twins present unique diagnostic and etiological challenges.
- Exencephaly, anencephaly, and acephaly are severe neural tube defects.
Purpose of the Study:
- To report and analyze three cases of monozygous male twins with discordant severe congenital abnormalities.
- To investigate potential etiological factors, including environmental influences, in these rare twin presentations.
Main Methods:
- Pathologic examination to confirm monozygosity.
- Blood group antigen testing in one case for corroboration.
- Clinical and pathological review of the affected twin pairs.
Main Results:
- Three cases of monozygous male twins were identified, with one twin exhibiting exencephaly/anencephaly/acephaly and the cotwin being normal.
- Pathologic examination confirmed monozygosity in all cases.
- One case showed adrenal hypoplasia and chorionic vascular anastomoses, suggesting potential environmental influences.
Conclusions:
- Monozygosity with severe discordant congenital malformations can occur.
- Environmental factors, possibly acting through mechanisms like vascular anastomoses, may play a role in the etiology of these conditions.
- Further research is warranted to elucidate the interplay of genetic and environmental factors in twin developmental discordance.
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