| Phenotype and type | Ages and course | Evidence frequency | Suggested HPO term label | Primary source |
|---|---|---|---|---|
| Progressive sensory ataxia/myeloneuropathy — neurologic sign | Onset at 3–12 years in the original cohort; progressive, sometimes waxing and waning | 3/3 in the 2020 discovery cohort; not a population estimate | Sensory ataxia; Myelopathy; Axonal sensorimotor polyneuropathy | Chung et al., 2020 (pqac-00000005, pqac-00000022, pqac-00000024) |
| Bilateral sensorineural hearing loss — sensory sign | Childhood onset; progressive in reported cases | 3/3 in the 2020 discovery cohort narrative; not a population estimate | Bilateral sensorineural hearing impairment | Chung et al., 2020 (pqac-00000022, pqac-00000025) |
| Spinal-cord and brain white-matter lesions — imaging abnormality | Dorsal-column-predominant longitudinal spinal lesions may precede cerebral white-matter involvement; progression varies | Reported; frequency unknown | Spinal cord white-matter abnormality; Cerebral white-matter abnormality; Leukodystrophy | Chung et al., 2020; Raas et al., 2024 (pqac-00000005, pqac-00000020) |
| Seizures — neurologic symptom | Childhood or adolescent presentation/relapse in reported cases; longitudinal frequency is undefined | Reported; frequency unknown | Seizure | Jafarpour et al., 2022; Raas et al., 2024 (pqac-00000006, pqac-00000017) |
| Keratitis, corneal scarring, or visual decline — ocular manifestation | Reported during childhood/adolescent progression; may accompany neurologic decline | Reported; frequency unknown | Keratitis; Corneal scarring; Visual impairment | Jafarpour et al., 2022; Raas et al., 2024 (pqac-00000006, pqac-00000038) |
| Ichthyotic rash and/or alopecia — cutaneous manifestation | Rash may wax and wane and can precede or accompany neurologic manifestations; alopecia reported in one case | Reported; frequency unknown | Ichthyosis; Alopecia | Jafarpour et al., 2022; Raas et al., 2024 (pqac-00000006, pqac-00000017, pqac-00000019) |
| Normal plasma very-long-chain fatty acids — laboratory finding | Documented despite progressive disease; distinguishes gain-of-function Mitchell syndrome from recessive ACOX1 deficiency | 3/3 in the 2020 discovery cohort; not a population estimate | Normal very-long-chain fatty-acid concentration | Chung et al., 2020 (pqac-00000005, pqac-00000022, pqac-00000031) |


*Table: Compact phenotype summary grounded in the original human discovery cohort and subsequent primary case reports (pqac-00000005, pqac-00000006, pqac-00000017). Fractions of 3/3 describe only the ascertainment-biased 2020 discovery cohort and must not be interpreted as population frequencies.*