Dizygotic opposite-sex twins with surgically repaired concordant myelomeningocele conceived by in vitro fertilization using intracytoplasmic sperm injection: a case report and review of the literature

BACKGROUND: Myelomeningocele (MMC) is a common subtype of congenital neural tube defects (NTD). Although congenital malformations including NTD are more common in twins, concordance, especially in dizygotic twins, is extremely rare and is found mostly in same-sex twins. The role of genetic and environmental factors in the etiology of MMC is unclear. CASE REPORT: Dizygotic twins of opposite sex were born at term to a 35-year-old woman conceived with in vitro fertilization (IVF) using intracytoplasmic sperm injection (ICSI). Prenatal ultrasonography (US) revealed concordant lumbosacral MMC at 18 weeks of gestation as well as ventriculomegaly and Arnold-Chiari malformation type II at 28 weeks. Both twins underwent surgical repair of the MMC within 48 h after birth and required a ventriculoperitoneal shunt in the second week of life. DISCUSSION: The case presented raises questions concerning the etiology of MMC, since in twins, it is compelling to attribute the etiology to genetic factors. In the literature, 22 pairs of twins with concordant MMC have been reported, and of the 10 dizygotic twins described, four were of opposite sex. However, in monozygotic twins, most of the cases are non-concordant; therefore, the role of genetics remains unclear. In addition, environmental factors such as nutrition, metabolic folic acid deficiency, and assisted conception with IVF and ICSI might play a role as well. CONCLUSION: The appearance of concordant MMC in opposite-sex dizygotic twins, conceived by IVF using ICSI, intrigues questions concerning the etiology of MMC. In such cases, genetic counseling and evaluation should be considered.