<unk>  is named so by combining the Greek prefix a- (without, lacking) and -prosencephalon (the embryonic forebrain). The syndromic form is known as<unk> , with 'X' and 'K' referring to the surnames of the first two patients described with<unk> .
XK aprosencephaly
Holoprosencephaly
Hemimegalencephaly
Schizencephaly
Microlissencephaly
Hydranencephaly
Lissencephaly
Microhydranencephaly