The 18ph+ chromosome heteromorphism.
Zelante
L
L
Notarangelo
A
A
Dallapiccola
B
B
D002869:Chromosome Aberrations; D025063:Chromosome Disorders; D002887:Chromosomes, Human, Pair 18 / Q000235:genetics*; D005260:Female; D006801:Humans; D011247:Pregnancy; D011296:Prenatal Diagnosis