| Phenotype | Frequency in centromeric 18p- cohort | Suggested HPO term(s) | Typical onset | Usual severity / course | Notes / evidence |
|---|---:|---|---|---|---|
| Hypotonia / mixed tone abnormalities | 84% | HP:0001252 Hypotonia; HP:0003808 Abnormality of muscle tone | Neonatal–infancy | Mild to moderate; often persistent developmental impact | Common early neurologic feature in centromeric 18p- (pqac-00000003) |
| Neonatal complications (jaundice, respiratory distress, feeding difficulties) | 71% | HP:0001945 Respiratory distress; HP:0011968 Feeding difficulties; HP:0002904 Neonatal hypoglycemia/jaundice not specifically resolved | Neonatal | Variable; may require supportive care | Composite category reported in review table (pqac-00000003) |
| MRI anomalies (excluding holoprosencephaly spectrum) | 66% | HP:0410263 Abnormal brain MRI; HP:0002538 Abnormal cerebral white matter morphology | Congenital / childhood recognition | Variable; often nonprogressive structural findings | White matter abnormalities and other MRI findings frequently observed (pqac-00000003, pqac-00000006) |
| Recurrent otitis media | 61% | HP:0000389 Recurrent otitis media | Infancy–childhood | Recurrent; may contribute to conductive hearing loss | Often associated with chronic middle-ear disease (pqac-00000003) |
| Heart defects | 56% | HP:0001627 Abnormality of the cardiovascular system; HP:0001629 Ventricular septal defect; HP:0001636 Tetralogy of Fallot | Congenital | Variable from mild to surgically significant | Structural cardiac defects are common; prenatal VSD also reported (pqac-00000003, pqac-00000001) |
| Ptosis | 55% | HP:0000508 Ptosis | Congenital / infancy | Mild to moderate; often persistent | Characteristic craniofacial/ophthalmic feature (pqac-00000003) |
| Refractive errors | 52% | HP:0000545 Myopia; HP:0000539 Refractive error | Childhood | Mild to moderate; usually manageable with correction | Broad ophthalmic involvement is frequent (pqac-00000003) |
| Strabismus | 42% | HP:0000486 Strabismus | Infancy–childhood | Mild to moderate; may need ophthalmologic management | Common visual alignment abnormality (pqac-00000003, pqac-00000008) |
| Pectus excavatum | 29% | HP:0000767 Pectus excavatum | Childhood | Usually mild to moderate; generally stable | Skeletal/chest wall manifestation (pqac-00000003) |
| Hearing loss (overall) | 23% | HP:0000365 Hearing impairment; HP:0000405 Conductive hearing impairment; HP:0000407 Sensorineural hearing impairment | Childhood | Usually mild to moderate; conductive more common than sensorineural | Review table reports hearing loss overall 23%; critical-region analysis separated conductive 22% and sensorineural 8% penetrance (pqac-00000003, pqac-00000008) |
| Isolated growth hormone deficiency | 23% | HP:0000824 Growth hormone deficiency; HP:0001510 Growth delay | Childhood | Variable; treatable when recognized | Endocrine surveillance recommended in review (pqac-00000003, pqac-00000008) |
| Scoliosis / kyphosis | 19% | HP:0002650 Scoliosis; HP:0002808 Kyphosis | Childhood–adolescence | Mild to moderate; occasionally requires bracing/surgery | Combined axial skeletal phenotype (pqac-00000003, pqac-00000008) |
| Pes planus | 19% | HP:0001763 Pes planus | Childhood | Usually mild; may affect gait/endurance | Common orthopedic feature (pqac-00000003) |
| Cryptorchidism | 14% | HP:0000028 Cryptorchidism | Congenital | Variable; may require orchiopexy | Male genital anomaly; micropenis also described in prenatal case literature (pqac-00000003, pqac-00000001) |
| Panhypopituitarism / hypopituitarism | 13% | HP:0000826 Hypopituitarism; HP:0000873 Panhypopituitarism | Congenital / childhood | Potentially severe; chronic hormone replacement often required | Includes structural pituitary anomalies in some patients (pqac-00000003, pqac-00000006) |
| Seizures | 13% | HP:0001250 Seizure | Childhood | Variable; often intermittent/managed medically | Included grand mal, absence, and partial complex seizures in review cohort (pqac-00000003, pqac-00000008) |
| Immunoglobulin deficiency (IgA, IgG, or IgM deficiency) | 13% | HP:0002721 Immunodeficiency; HP:0002205 Recurrent infections; HP:0011347 Decreased circulating IgA level | Childhood | Variable; may predispose to infections/autoimmunity | IgA deficiency specifically reported in review and later case reports (pqac-00000003, pqac-00000009) |
| Holoprosencephaly or HPE microform | 13% | HP:0001360 Holoprosencephaly; HP:0000668 Single central incisor | Prenatal / congenital | Severe in classic HPE, milder in microforms | TGIF1 hemizygosity is a major mechanistic candidate; penetrance incomplete (pqac-00000003, pqac-00000005) |
| Autoimmune disorder | 10% | HP:0002960 Autoimmunity; HP:0000821 Hypothyroidism; HP:0002725 Systemic lupus erythematosus; HP:0012205 Alopecia | Childhood–adult | Variable; chronic, organ-specific or systemic | Review lists rheumatoid arthritis, celiac disease, alopecia, vitiligo, lupus, Sjögren syndrome, autoimmune thyroid disease (pqac-00000003, pqac-00000006, pqac-00000009) |
| Sacral agenesis | 6% | HP:0003310 Sacral agenesis | Congenital | Moderate to severe; structural | Rare but recurrent caudal malformation (pqac-00000003) |
| Optic nerve hypoplasia | 6% | HP:0008058 Optic nerve hypoplasia | Congenital / infancy | Variable visual impairment | Part of ophthalmologic/neurodevelopmental spectrum (pqac-00000003) |
| Congenital cataracts | 6% | HP:0000519 Congenital cataract | Congenital | Variable; may need surgery | Rare but documented ocular feature (pqac-00000003, pqac-00000008) |
| Myelomeningocele | 3% | HP:0002414 Myelomeningocele | Congenital | Severe structural defect | Uncommon neural tube defect in reported cohort (pqac-00000003) |


*Table: This table summarizes the principal phenotypes reported in the comprehensive Hasi-Zogaj 2015 review of chromosome 18p deletion syndrome, including frequencies, suggested HPO mappings, onset, and usual severity/course. It is useful for knowledge-base phenotype annotation and anticipatory clinical assessment.*