We read with considerable interest the paper by Kohli et al. regarding the detection of complex congenital heart disease in dichorionic diamniotic twins. We had the opportunity to compare their cases with the twin pregnancies that we personally evaluated. Last year we reported a series of four diamniotic dichorionic pregnancies with discordant fetal cardiac phenotype [1]. In all cases the twin with fetal growth restriction developed aortic coarctation. Regardless of the etiopathogenetic mechanism, we consider it interesting that aortic coarctation is also present in several fetuses reported by Kohli et al. However, to understand the risks of cardiovascular malformations in dichorionic diamniotic twin pregnancies and to define the prevalence of specific groups of heart disease, it is essential to know zygosity. For this purpose it would be interesting to evaluate, where possible, the single nucleotide polymorphisms of the twin pairs included in the cohort. In particular, both fetuses of Patient 1 presented echocardiographic features suggestive of 22q11.2 deletion syndrome (especially anomalies of the left pulmonary artery [2]), but it would seem that chromosomal microarray analysis was not performed in the living twin. In the fetuses of Patient 2 there was a family history of congenital heart disease which led to a significant increase in the risk of presenting this type of malformation, introducing a possible bias in the case study. Regarding the cases reported in the literature and included in the paper, in a dizyotic twin pregnancy the diagnosis of trisomy 21 was present in both fetuses [3], aneuploidy characterized by congenital heart disease in approximately half of cases. Obviously, if a chromosomal, genomic or monogenic alteration consistent with defects in cardiovascular development were also present in other pairs of twins, these should be excluded from the case study, as the heart disease would not be correlated to the dichorionic diamniotic pregnancy. Genetic investigations are proposed in all pregnancies in which a cardiovascular malformation is found. Further studies, with cytogenetic and molecular testing that include in the first instance an evaluation of zygosity, karyotype and chromosomal microarray analysis, will be essential to add information regarding the prevalence and pathophysiology of heart disease in dichorionic diamniotic twin pregnancies.