FOXC1 deletion, duplication, and mutations are associated with Axenfeld-Rieger anomaly, and Dandy-Walker malformation spectrum. We describe the clinical history, physical findings, and available brain imaging studies in three fetuses, two children, and one adult with 6p25 deletions encompassing FOXC1. Various combinations of ocular and cerebellar malformations were found. In all three fetuses, necropsy including detailed microscopic assessments of the eyes and brains showed ocular anterior segment dysgenesis suggestive of Axenfeld-Rieger anomaly. Five 6p25 deletions were terminal, including two derived from inherited reciprocal translocations; the remaining 6p25 deletion was interstitial. The size and breakpoints of these deletions were characterized using comparative genomic hybridization arrays. All six deletions included FOXC1. Our data confirm that FOXC1 haploinsufficiency plays a major role in the phenotype of patients with 6p25 deletions. Histopathological features of Axenfeld-Rieger anomaly were clearly identifiable before the beginning of the third-trimester of gestation.

This study is the first report to present the cross-distribution of chorionicity and zygosity in triplet pregnancies as a function of their mode of conception. In triplet pregnancies conceived using ART, DC triplets are always DZ, and TC triplets are almost always TZ.

Early prenatal diagnosis of chorionicity is of major importance in triplet pregnancy. Experienced sonographers must quickly evaluate any uncertain diagnosis. In cases of unknown chorionicity, other ultrasonographic criteria can highlight high-risk triplet pregnancy, but at a later stage.

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