| Phenotype / feature | Frequency among reported patients | Severity / variability | Typical age of onset | Suggested HPO term(s) | Key citations |
|---|---:|---|---|---|---|
| Developmental delay / global developmental delay | 13/13 (100%) in initial cohort; also core feature in later reports | Mild to severe; variable course | Infancy / early childhood | HP:0001263 Global developmental delay; HP:0011344 Severe global developmental delay | (pqac-00000001, pqac-00000015, pqac-00000002, pqac-00000004) |
| Intellectual disability | Present in essentially all reported individuals, though severity ranges from borderline to moderate/severe; some described as DD/ID rather than formal ID | Borderline/mild to moderate; severe developmental impairment in rare neonatal cases | Usually recognized in childhood | HP:0001249 Intellectual disability; HP:0001256 Mild intellectual disability; HP:0002342 Moderate intellectual disability | (pqac-00000001, pqac-00000006, pqac-00000015, pqac-00000005) |
| Speech delay / language disorder | 13/13 (100%) in initial cohort | Often severe; expressive language commonly more impaired than receptive language | Infancy / toddler years | HP:0000750 Delayed speech and language development; HP:0002463 Language impairment | (pqac-00000001, pqac-00000006, pqac-00000015, pqac-00000005) |
| Childhood apraxia of speech / severe speech production disorder | 3/13 (~23%) in initial cohort explicitly described with speech apraxia | Can be profound, including nonverbal status or limited verbal output | Early childhood | HP:0012469 Childhood apraxia of speech; HP:0001344 Expressive language delay | (pqac-00000000, pqac-00000006) |
| Motor developmental delay | 7/13 (~54%) in initial cohort; recurrent in later case reports | Mostly gross motor delay; variable | Infancy | HP:0001270 Motor delay; HP:0002194 Delayed gross motor development; HP:0010862 Delayed fine motor development | (pqac-00000000, pqac-00000008, pqac-00000005, pqac-00000017) |
| Hypotonia | 3/13 (~23%) in initial cohort; described as common infantile feature in later summaries | Usually mild to moderate; often infantile | Infancy | HP:0001252 Muscular hypotonia | (pqac-00000008, pqac-00000005, pqac-00000004) |
| Autism spectrum disorder | 5/13 (~38%) in initial cohort; recurrent across later reports and reviews | Variable behavioral severity | Childhood | HP:0000729 Autism | (pqac-00000000, pqac-00000001, pqac-00000005, pqac-00000009) |
| Attention-deficit / hyperactivity disorder | 3/13 (~23%) in initial cohort | Variable | Childhood / school age | HP:0007018 Attention deficit hyperactivity disorder | (pqac-00000000, pqac-00000001, pqac-00000005) |
| Dysmorphic facial features | Common; described as overlapping facial gestalt in multiple patients | Usually mild to moderate; variable expressivity | Congenital / infancy | HP:0001999 Facial dysmorphism; HP:0000316 Hypertelorism; HP:0000450 Broad nasal bridge; HP:0010800 Long philtrum / HP:0000343 Long philtrum as applicable | (pqac-00000007, pqac-00000005, pqac-00000016, pqac-00000017) |
| Eye / vision abnormalities (overall) | 8/13 (~62%) in initial cohort | Mild to severe; includes structural and functional abnormalities | Congenital or childhood | HP:0000505 Visual impairment; HP:0000618 Blindness / low vision umbrella if severe; HP:0000529 Progressive visual loss where relevant | (pqac-00000008, pqac-00000015, pqac-00000002) |
| Optic nerve abnormalities | 3/13 in initial cohort; severe optic nerve/chiasm atrophy in neonatal case | Variable, can be severe | Congenital / childhood | HP:0001138 Optic atrophy; HP:0001098 Abnormality of the optic nerve | (pqac-00000008, pqac-00000002, pqac-00000016) |
| Duane anomaly / strabismus spectrum | Duane anomaly 2/13 (~15%); strabismus also reported | Variable | Congenital / early childhood | HP:0009928 Duane anomaly; HP:0000486 Strabismus | (pqac-00000008, pqac-00000015) |
| Astigmatism / nystagmus / retinal findings | Each uncommon but recurrent across cases | Variable | Childhood / congenital | HP:0000483 Astigmatism; HP:0000639 Nystagmus; HP:0000556 Retinal dystrophy | (pqac-00000008, pqac-00000016) |
| Congenital heart defects / mild cardiac anomalies | 2/13 (~15%) in initial cohort; more severe congenital heart disease in 2024 neonatal case | Usually mild in early cohort; rare severe neonatal presentation | Congenital | HP:0001627 Abnormality of the cardiovascular system; HP:0001631 Aortic root dilatation; HP:0001671 Atrial septal defect; HP:0001629 Ventricular septal defect; HP:0001680 Coarctation of aorta / isthmus hypoplasia as applicable | (pqac-00000008, pqac-00000002, pqac-00000016) |
| Epilepsy / seizures | Rare in initial cohort (1/13, ~8%); later reports expanded spectrum to epileptic encephalopathy | Can be severe and drug-resistant when present | Childhood or infancy depending on case | HP:0001250 Seizure; HP:0002123 Generalized myoclonic seizure; HP:0012468 Epileptic encephalopathy | (pqac-00000008, pqac-00000003, pqac-00000016) |
| Brain MRI abnormalities | Uncommon in original cohort but increasingly recognized in later reports | Variable; from mild frontal atrophy to severe callosal/brainstem/chiasmal abnormalities | Infant / childhood | HP:0001273 Abnormality of the corpus callosum; HP:0002060 Abnormality of the cerebral white matter; HP:0002283 Ventriculomegaly; HP:0007364 Hydrocephalus | (pqac-00000008, pqac-00000002, pqac-00000016, pqac-00000009) |
| Corpus callosum abnormalities | Reported in severe recent cases/reviews | Moderate to severe | Congenital / infancy | HP:0001273 Abnormality of the corpus callosum; HP:0002079 Hypoplasia of the corpus callosum | (pqac-00000002, pqac-00000016, pqac-00000009) |
| Microcephaly / growth restriction / short stature | Reported in subset; severe neonatal case had growth restriction; later family report notes restricted growth | Variable | Prenatal or postnatal | HP:0000252 Microcephaly; HP:0001511 Intrauterine growth restriction; HP:0004322 Short stature | (pqac-00000002, pqac-00000004, pqac-00000017) |
| Chronic constipation / obstipation / megacolon | Obstipation in 4/13 (~31%) in initial cohort; congenital megacolon reported as novel complication in family report | Usually chronic; occasionally severe | Infancy / childhood | HP:0002019 Constipation; HP:0002240 Chronic constipation; HP:0012707 Megacolon | (pqac-00000008, pqac-00000004, pqac-00000017) |
| Hearing loss | 2/13 (~15%) conductive hearing loss in initial cohort; hearing/vision problems noted in later reports | Mild to moderate | Childhood | HP:0000405 Conductive hearing impairment; HP:0000365 Hearing impairment | (pqac-00000007, pqac-00000002) |
| Orthopedic / skeletal anomalies | Recurrent but variable; scoliosis, pes cavus, brachydactyly, hip dysplasia, valgus-pronated feet reported | Mild to moderate | Childhood / congenital | HP:0002650 Scoliosis; HP:0001761 Pes cavus; HP:0001156 Brachydactyly; HP:0001385 Hip dysplasia | (pqac-00000007, pqac-00000005) |
| Severe multisystem neonatal presentation | Very rare; single recent neonate with hydrocephalic changes, optic/chiasm atrophy, bowel atresia, cardiac disease, multiple organ failure, neonatal death | Severe / potentially lethal | Prenatal to neonatal | HP:0001627 Abnormality of the cardiovascular system; HP:0001138 Optic atrophy; HP:0002079 Hypoplasia of the corpus callosum; HP:0002586 Ileal atresia; HP:0003819 Neonatal death | (pqac-00000002, pqac-00000016) |


*Table: This table summarizes the core and variable clinical features reported for MED13 syndrome, including approximate frequencies, severity patterns, onset, suggested HPO mappings, and supporting citations. It is useful for disease knowledge base curation and phenotype annotation.*