| Domain | Best-supported finding | Evidence type/strength | Key source/date/DOI |
|---|---|---|---|
| Disease definition | DFNB79 is an autosomal recessive, nonsyndromic deafness caused by biallelic truncating variants in **TPRN** (formerly **C9orf75**), encoding taperin. (pqac-00000003, pqac-00000007) | Human discovery study; strong disease-gene evidence | Rehman et al., *Am J Hum Genet*, Mar 2010, https://doi.org/10.1016/j.ajhg.2010.01.030 |
| Inheritance | Inheritance is **autosomal recessive**; original evidence came from multiple **consanguineous Pakistani families** linked to DFNB79. (pqac-00000003, pqac-00000007) | Human pedigree/linkage + segregation; strong | Rehman et al., Mar 2010, 10.1016/j.ajhg.2010.01.030 |
| Gene/locus | **TPRN** maps to **chromosome 9q34.3**; the DFNB79 critical interval analyzed was ~2.9 Mb. Mouse ortholog is syntenic to chromosome 2qA3. (pqac-00000003, pqac-00000006, pqac-00000007) | Human mapping + comparative genomics; strong | Rehman et al., Mar 2010, 10.1016/j.ajhg.2010.01.030 |
| Hallmark phenotype | Best-supported clinical phenotype is **prelingual, bilateral, severe-to-profound sensorineural hearing loss** with **normal vestibular function** and no syndromic features reported in the discovery families. (pqac-00000007) | Human clinical phenotype from original families; moderate-strong | Rehman et al., Mar 2010, 10.1016/j.ajhg.2010.01.030 |
| Landmark variants | Discovery variants were all truncating and located in exon 1: **c.1056G>A (p.Trp352Ter/W352X)**, **c.1244delC**, **c.44_54dup**, and **c.42_52del**; absent in reported controls. (pqac-00000003, pqac-00000004) | Human molecular genetics; strong | Rehman et al., Mar 2010, 10.1016/j.ajhg.2010.01.030 |
| Cellular site | Taperin is concentrated at the **taper/base region of hair-cell stereocilia** in the cochlea. (pqac-00000004, pqac-00000007) | Human-linked mouse localization data; strong for localization, indirect for human disease tissue | Rehman et al., Mar 2010, 10.1016/j.ajhg.2010.01.030 |
| Core mechanism | Best-supported mechanism: loss of TPRN/taperin disrupts the **stereociliary taper/rootlet membrane–actin complex**; taperin interacts functionally with **GRXCR2, CLIC5, radixin, MYO6, and PTPRQ**, and mislocalization or loss causes stereocilia disorganization, hair-cell degeneration, and hearing loss. Direct human mechanistic proof remains limited. (pqac-00000000, pqac-00000001, pqac-00000002, pqac-00000004) | Mouse/cellular mechanistic evidence; moderate for human inference | Liu et al., *Cell Reports*, Oct 2018, https://doi.org/10.1016/j.celrep.2018.09.063; Salles et al., 2014 cited within gathered evidence |
| Epidemiology | **No DFNB79-specific prevalence/incidence estimate** was identified in gathered evidence. Broader extrapolation: congenital hearing loss affects about **1–3 per 1,000 live births** and a large fraction is genetic; AR forms predominate among nonsyndromic cases. (pqac-00000008, pqac-00000009, pqac-00000012) | Broader hearing-loss reviews only; weak for DFNB79-specific epidemiology | Yun & Lee, Apr 2024, 10.7874/jao.2024.00157; Brotto et al., Feb 2024, 10.3390/audiolres14020022; Lee et al., Jun 2024, 10.3390/biomedicines12071427 |
| Diagnosis | Disease-specific diagnosis is best supported by **molecular testing of TPRN** in the setting of congenital/prelingual ARNSHL. Broader extrapolation: contemporary practice favors **hearing-loss gene panels first**, with **exome/genome/CNV analysis** when panel testing is unrevealing. (pqac-00000003, pqac-00000008, pqac-00000012, pqac-00000014) | Human disease-gene evidence + broader clinical practice reviews; moderate | Rehman et al., Mar 2010, 10.1016/j.ajhg.2010.01.030; Lee et al., Jun 2024, 10.3390/biomedicines12071427 |
| Treatment | **No TPRN-specific pharmacologic or gene-replacement treatment** in humans was identified. Broader extrapolation: management of severe congenital genetic hearing loss currently relies on **hearing aids** and especially **cochlear implantation** when indicated. (pqac-00000009, pqac-00000012, pqac-00000014) | Broader hearing-loss management evidence; weak for TPRN-specific efficacy | Brotto et al., Feb 2024, 10.3390/audiolres14020022; Lee et al., Jun 2024, 10.3390/biomedicines12071427 |
| Trials | **No TPRN-specific clinical trial** was identified in gathered evidence. Active hereditary hearing-loss gene-therapy trials currently target other genes, especially **OTOF/DFNB9**; these results should **not** be attributed to TPRN-related DFNB79. (pqac-00000010, pqac-00000011, pqac-00000013) | Clinical-trial/review evidence; strong for absence in gathered evidence, not proof of global absence | Brotto et al., Feb 2024, 10.3390/audiolres14020022; Duhon et al., Jul 2024, 10.3389/fauot.2024.1423853 |
| Evidence gaps | Key gaps: no accessible second 2010 AJHG/2013 family full extraction in gathered evidence, limited DFNB79-specific natural-history and population-frequency data, sparse direct human mechanistic data, and inaccessible 2024 TPRN-ring paper during retrieval. (pqac-00000003, pqac-00000004, pqac-00000008, pqac-00000011) | Evidence-gap assessment; moderate | Based on gathered evidence corpus through 2024 |


*Table: This table condenses the highest-confidence findings for TPRN-related DFNB79, separating disease-specific evidence from broader hereditary hearing-loss extrapolation. It is useful for rapid knowledge-base population and for identifying where evidence remains sparse, especially treatment and trial data.*