Vein of Galen Aneurysmal Malformation in Monozygotic Twin.
BACKGROUND
Vein of Galen aneurysmal malformation (VGAM) is a rare pediatric vascular malformation of the brain. Genetic backgrounds are not well elucidated. We report on a monozygotic twin with VGAM and his endovascular treatment, and the genetic analyses of the twins and their parents.


METHODS
In a monochorionic, diamniotic pregnancy of a 28-year-old healthy woman, monozygotic twins were born by emergency caesarian section because of fetal distress of the smaller twin at 25 weeks' and 4 days' gestation. Although a postnatal cranial ultrasound failed to detect VGAM in the smaller twin, mild heart failure persisted. A brain magnetic resonance (MR) examination of this twin on day 82 revealed choroidal VGAM. The twin was treated successfully by two sessions of embolization at 6 and 8 months of age. An MR examination at 1 year showed minimal residual arteriovenous shunts. He developed normally similar to the normal co-twin, with a follow-up period of 1 year and 6 months. As for the affected twin, no germline mutation or copy number variations were identified in ENG, ALK1, SMAD4, BMPR2, PTEN, RASA1, KRIT1, Marcavernin, or PDCD10 through whole-exome sequencing (WES).


CONCLUSIONS
We have reported a rare combination of a monozygotic twin and VGAM and the successful endovascular treatment. Phenotypic discordance in monozygotic twins established early in embryogenesis could be attributable to environmental or epigenetic factors.
Department of Neurointervention, Osaka City General Hospital, Osaka, Japan. Electronic address: komiyama@japan-mail.com.
Masaki
M
Komiyama
Department of Neonatology, Osaka City General Hospital, Osaka, Japan.
Satoko
S
Miyatake
Department of Neurointervention, Osaka City General Hospital, Osaka, Japan.
Aiko
A
Terada
Department of Neurointervention, Osaka City General Hospital, Osaka, Japan.
Tomoya
T
Ishiguro
Human Genetics, Yokohama City University Graduate School of Medicine, Yokohama, Japan.
Hiroyuki
H
Ichiba
Department of Neonatology, Osaka City General Hospital, Osaka, Japan.
Naomichi
N
Matsumoto
D001921:Brain / Q000000981:diagnostic imaging; D056915:DNA Copy Number Variations / Q000235:genetics; D057510:Endovascular Procedures / Q000379:methods*; D006801:Humans; D007223:Infant; D018810:Magnetic Resonance Angiography; D008279:Magnetic Resonance Imaging; D014430:Twins, Monozygotic; D054080:Vein of Galen Malformations / Q000000981:diagnostic imaging / Q000235:genetics* / Q000601:surgery*
Embolization; Gene analysis; Identical twin; Vein of Galen aneurysmal malformation; Whole-exome sequencing