Rare diseases · Sign or symptom
Hearing impairment
Deafness
HP:0000365
What it means
A decreased magnitude of the sensory perception of sound.
Hearing loss can be categorized by which part of the auditory system is damaged, as conductive hearing loss, sensorineural hearing loss, and mixed hearing loss. Another axis of classification uses the degree of hearing impairment. The degree of hearing loss is computed by using a three frequency average taken at 500 Hz, 1,000 Hz and 2,000 Hz. The average of these three frequencies is called the Pure Tone Average (PTA). 0-20 dB is considered normal, 21-40 dB mild loss, 41-60 dB moderate loss, 61-70 dB moderately severe loss,71-90 dB severe loss, and greater than 90 dB profound loss. Note that the word deafness is occasionally used to describe partial hearing loss. The World Health Organization uses the word deafness to refer to complete loss of the ability to hear, and hearing impairment to refer to any degree of reduced hearing.
In everyday care
Most people with this sign do not have a rare disease — it appears in common conditions far more often. These general reference pages cover the same topic:
Rare diseases that can present with this378
Very common80–99%
65- 3MC syndrome
- 8q21.11microdeletion syndrome
- Alopecia-intellectual disability syndrome
- Alpha-mannosidosis
- Alpha-N-acetylgalactosaminidase deficiency
- Alpha-N-acetylgalactosaminidase deficiency type 1
- Arachnoiditis
- Autosomal recessive malignant osteopetrosis
- Barber-Say syndrome
- Beta-mannosidosis
- Blepharophimosis-intellectual disability syndrome, Ohdo type
- BOR syndrome
- Branchiootic syndrome
- Camptodactyly-tall stature-scoliosis-hearing loss syndrome
- CHARGE syndrome
- CHIME syndrome
- CINCA syndrome
- Cockayne syndrome type 1
- Corpus callosum agenesis-intellectual disability-coloboma-micrognathia syndrome
- Coxoauricular syndrome
- Cutaneous mastocytosis-deafness-microtia syndrome
- Deafness-enamel hypoplasia-nail defects syndrome
- Deafness-epiphyseal dysplasia-short stature syndrome
- Deafness with labyrinthine aplasia, microtia, and microdontia
- Duplication of the pituitary gland
- Dysosteosclerosis
- Fabry disease
- Fetal methylmercury syndrome
- Frontometaphyseal dysplasia
- Fucosidosis
- Galactosialidosis
- GM1 gangliosidosis type 1
- GRACILE syndrome
- Hypertrichosis lanuginosa congenita
- Infantile-onset spinocerebellar ataxia
- Intellectual disability-seizures-macrocephaly-obesity syndrome
- IVIC syndrome
- Krabbe disease
- Mucopolysaccharidosis type 4
- Myhre syndrome
- Nager syndrome
- Oculocerebral hypopigmentation syndrome, Preus type
- Olivopontocerebellar atrophy-deafness syndrome
- Osteogenesis imperfecta
- Otopalatodigital syndrome type 1
- Otopalatodigital syndrome type 2
- PCNA-related progressive neurodegenerative photosensitivity syndrome
- Prolidase deficiency
- Reticular dysgenesis
- RFT1-CDG
- Richards-Rundle syndrome
- Sandhoff disease
- Sensorineural deafness with dilated cardiomyopathy
- Severe motor and intellectual disabilities-sensorineural deafness-dystonia syndrome
- Sialidosis type 2
- Spinocerebellar ataxia type 36
- Tietz syndrome
- Upper limb defect-eye and ear abnormalities syndrome
- Waardenburg-Shah syndrome
- Waardenburg syndrome
- Waardenburg syndrome type 1
- Waardenburg syndrome type 2
- Waardenburg syndrome type 3
- Xeroderma pigmentosum-Cockayne syndrome complex
- X-linked Charcot-Marie-Tooth disease type 5
Common30–79%
15- 20q11.2microdeletion syndrome
- 22q11.2deletion syndrome
- Ablepharon macrostomia syndrome
- Achondroplasia
- Acquired partial lipodystrophy
- Acrodysostosis
- Adult-onset chronic progressive external ophthalmoplegia with mitochondrial myopathy
- AGel amyloidosis
- ALG11-CDG
- ALG3-CDG
- Alpha-N-acetylgalactosaminidase deficiency type 2
- Alport syndrome-intellectual disability-midface hypoplasia-elliptocytosis syndrome
- Anophthalmia/microphthalmia-esophageal atresia syndrome
- Autosomal dominant dopa-responsive dystonia
- Autosomal dominant spastic paraplegia type 29
The range is how often this sign appears among people diagnosed with each disease — it is not a probability of having any of them. Many of these signs also occur in common, non-rare conditions, and Orphanet separately records 4 diseases where this sign is specifically absent. A sign on this page is a conversation to have with a clinician, not a conclusion.
Part of the broader category
Also called: Hearing defect · Hearing loss · Hypacusis · Hypoacusis
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Start free with EleplanThis page uses the Human Phenotype Ontology (2026-06-23) — Human Phenotype Ontology Consortium, hpo.jax.org. Disease associations from Orphanet (INSERM), CC BY 4.0. Content is educational and is not medical advice.