Twin brothers with MIDAS syndrome and XX karyotype.

Twin brothers with microphthalmia, facial dermal hypoplasia, sclerocornea, and supraventricular tachycardia, are reported. Their clinical features are compatible with MIDAS syndrome, a known X-linked and hemizygous male lethal condition. Their karyotypes showed an XX sex chromosome modality with a subtle Xp/Yp translocation proven by the presence of SRY gene. The pregnancy was complicated with fetal supraventricular tachycardia, which was treated with digoxin prenatally. Postnatally, both twins required treatment with adenosine, digoxin, and propanolol to remain in normal sinus rhythm. The possible involvement of the heart, only in the form of cardiomyopathy with arrhythmia is emphasized. Both twins had a selective X-inactivation of the derivative chromosome X with Xp/Yp translocation.