Growth hormone (GH) insufficiency is often detected in individuals with short stature, and serum immunoglobulin A levels may be low or absent.

[2] Patients typically have petite frames, a short neck, and a distinctive stance in which they lean slightly forward while standing with their legs spread wide.

The palate may be highly arched, the lateral incisors are occasionally absent, and the poorly positioned teeth have severe caries.

Large and floppy, with disconnected pinnae and a hypoplastic anthelix, the ears are frequently low-set and turned posteriorly.

Often indicative of Turner syndrome are a large chest with widely separated nipples or pectus excavatum, a short, occasionally webbed neck, and a low posterior hair line.

Although some individuals have been found to have normal or borderline mental development, the average intelligence quotient (IQ) ranges from 25 to 75, with most cases falling between 50 and 75.

[5] Holoprosencephaly (HPE), the primary abnormality, is characterized by aberrant development of the midface and forebrain and is linked to a wide range of phenotypes.

[6] Ten to fifteen percent of deletion 18p syndrome sufferers have severe brain anomalies linked to facial traits as cyplopia, cebocephaly, premaxillary agenesis, and bilateral cleft lip and palate.

[10] Numerous skeletal abnormalities, including coxa vara, hip dislocation, scoliosis and/or kyphosis, and foot deformities, have been documented.

[11] Rarely or sporadically, a number of other abnormalities have been documented, most frequently for deletion 18p due to an imbalanced translocation and concurrent partial trisomy.

[1] There have been reports of alopecia areata, hypotrichosis simplex,[15][7] and other uncommon cutaneous conditions like keratosis pilaris and ulerythema ophryogenes.

[20] Additional erasures 18p are the result of a partial trisomy for another chromosome and the malsegregation of a balanced paternal translocation with a variable breakpoint on 18p.

[23][24] Sometimes 18p is deleted as part of the ring 18 chromosome,[25] and other times it results from recombination in a pericentric inversion that causes an 18p monosomy linked to an 18q trisomy.

[1] When severe abnormalities are absent, patients with the most prevalent form of deletion 18p syndrome do not appear to have a worse chance of survival.