[1] Many cases often suffer with several other genetic disorders, and some have presented with hypoplasia, cleft lip, cardiac lesions and other heart defects.

Young–Madders syndrome is detectable from the fetal stage of development largely due to the distinctive consequences of holoprosencephaly, a spectrum of defects or malformations of the brain and face.

Facial defects which may manifest in the eyes, nose, and upper lip, featuring cyclopia, anosmia, or in the growth of only a single central incisor, and severe overlapping of the bones of the skull.

"[2] Both doctors noted no use of drugs, alcohol or cigarettes by the mother, and the baby was delivered normally after forty-one weeks of gestation.

Of the organs, Young and Madders noted missing parts of the tricuspid valve and other small cardiac defects, as well as the holoprosencephaly.

[2] Both doctors consulted various medical databases and, after discounting Meckel syndrome due to a lack of renal abnormalities, concluded that this was a hitherto unclassified condition.

In 1991 a publication in the Journal of Medical Genetics by a group of eight doctors, based on a five-patient case-study, argued that Trisomy 13 and Young–Madders syndrome were two distinct conditions and renamed the disorder to avoid confusion.

Problems with this chromosome account for several conditions including nonsyndromic deafness, Waardenburg syndrome and Wilson's disease.

[6] By 1994 a sufferer had been identified with a median cleft lip, cardiac and genital deformities which matched those found by Young and Madders.