T669C

# **General Information**

| **Position** | **669** | **Variant** | **m.669T\>C** | **Locus** | **MT\-RNR1** | **RNA** | **12S rRNA** |
| --- | --- | --- | --- | --- | --- | --- | --- |
| **Homoplasmy** | \+ | **Heteroplasmy** | \- | **mitoTIP** | N/A | **Pathogenicity** | Reported |

"Pathogenicity" status is derived from published literature or predictions from bioinformatics tools. Researchers and clinicians are cautioned that additional data and/or analysis may still be necessary to confirm the pathological significance of these variants. For more information, please see [Mitofam Info](https://mitofam.com/doc/385/).

# **Pedigree Information**

The **m.669T\>C** variant in MT\-RNR1 has been reported in 5 pedigrees. To date, 7 carriers have been reported. Homoplasmy was reported in 7/7 carriers (100%), and 7/7 carriers (100%) were affected. The main clinical manifestations among affected carriers included hearing loss, bilateral moderate hearing impairment, 100 dB left, 20 dB left, 86 dB left, bilateral vestibulopathy, medium to severe hearing loss, pTA 105 dB right, and other features.

| **No.** | **Position** | **Variant** | **Family ID** | **Nationality** | **Diseases** | **Unaffected Maternal Relatives** | **Affected Maternal Relatives** | **Publication Year** | **PMID/Ref** | **Note** |
| --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- |
| 1 | 669 | m.669T\>C | T669C\-F1 | China | Aminoglycoside\-induced and nonsyndromic hearing impairment | 2 | 6 | 2007 | [17637808](https://pubmed.ncbi.nlm.nih.gov/17637808/) | Family A |
| 2 | 669 | m.669T\>C | [T669C\-F2](https://mitofam.com/doc/1626/) | Poland | Nonsyndromic and aminoglycoside\-induced hearing loss | 0 | 2 | 2010 | [20353758](https://pubmed.ncbi.nlm.nih.gov/20353758/) | Family G52 |
| 3 | 669 | m.669T\>C | T669C\-F3 | Poland | Nonsyndromic and aminoglycoside\-induced hearing loss | ND | ND | 2010 | [20353758](https://pubmed.ncbi.nlm.nih.gov/20353758/) | Family G130 |
| 4 | 669 | m.669T\>C | T669C\-F4 | Poland | Nonsyndromic and aminoglycoside\-induced hearing loss | ND | ND | 2010 | [20353758](https://pubmed.ncbi.nlm.nih.gov/20353758/) | Family M21c |
| 5 | 669 | m.669T\>C | T669C\-F5 | Germany | Bilateral vestibulopathy; no concurrent hearing loss for patient 57 | ND | ND | 2008 | [18851951](https://pubmed.ncbi.nlm.nih.gov/18851951/) |  |

# **Carrier Information**

| **No.** | **Position** | **Variant** | **Family ID** | **Carrier ID** | **Type (Fam/De novo/Uninf)** | **Gender (F/M)** | **Proband (Y/N)** | **Affected (Y/N)** | **Die/Alive(D/A)** | **Age** | **Blood Mutant Level** | **Muscle Mutant level** | **Urine Mutant level** | **Other Mutant level** | **Clinical Features** | **Note** |
| --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- |
| 1 | 669 | m.669T\>C | T669C\-F1 | T669C\-F1\-P1 | Fam | ND | Y | Y | ND | ND | Homo | / | / | / | Medium to severe hearing loss; tinnitus | Original carrier ID: Family\-A\-proband; childhood to early adulthood onset; 7 deaf of 9 maternal relatives |
| 2 | 669 | m.669T\>C | T669C\-F2 | T669C\-F2\-II2 | Fam | F | Y | Y | ND | onset 16 | Homo | / | / | / | Hearing loss; PTA 105 dB right, 100 dB left | gentamicin exposure; family history yes (2 affected maternal relatives) |
| 3 | 669 | m.669T\>C | T669C\-F3 | T669C\-F3\-P1 | Uninf | M | Y | Y | ND | onset 5 | Homo | / | / | / | Hearing loss; PTA 70 dB right, 86 dB left | Original carrier ID: G130; gentamicin exposure; no family history |
| 4 | 669 | m.669T\>C | T669C\-F4 | T669C\-F4\-P1 | Uninf | F | Y | Y | ND | onset 54 | Homo | / | / | / | Hearing loss; PTA 75 dB right, 20 dB left | Original carrier ID: M21c; Gentamycin exposure; gentamicin exposure; no family history |
| 5 | 669 | m.669T\>C | T669C\-F5 | T669C\-F5\-P1 | Uninf | F | Y | Y | ND | 80 at onset | Homo | / | / | / | Bilateral vestibulopathy | Original carrier ID: Patient\-57; no gentamycin exposure |
| 6 | 669 | m.669T\>C | T669C\-F2 | T669C\-F2\-III1 | Fam | M | N | Y | ND | ND | Homo | / | / | / | Bilateral moderate hearing impairment | after gentamicin injection due to bronchitis |
| 7 | 669 | m.669T\>C | T669C\-F2 | T669C\-F2\-III2 | Fam | M | N | Y | ND | ND | Homo | / | / | / | Bilateral moderate hearing impairment | after gentamicin injection due to bronchitis |

For abbreviations and other usage instructions, please see [Mitofam Info](https://mitofam.com/doc/385/).