T1659C

# General Information

| **Position** | **1659** | **Variant** | **m.1659T\>C** | **Locus** | **MT\-TV** | **RNA** | **tRNA Val** |
| --- | --- | --- | --- | --- | --- | --- | --- |
| **Homoplasmy** | \- | **Heteroplasmy** | \+ | **mitoTIP** | 69\.60% | **Pathogenicity** | Reported \[VUS] |

"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.1659T\>C** variant in MT\-TV has been reported in 2 pedigrees. To date, 3 carriers have been reported. Reported mutation loads ranged from 7% to 99%, with a median of 81% overall; affected carriers showed mutation loads from 45% to 99%. In one affected carrier, a marked tissue\-specific difference was observed, with higher mutation loads in muscle (91%) than in bone marrow (45%). The main clinical manifestations among affected carriers included childhood\-onset encephalopathy, late\-onset encephalopathy, ataxia, bilateral putaminal lesions, cerebellar atrophy, end\-stage kidney disease(requiring haemodialysis), hemiplegia, hypertrophic cardiomyopathy, and other features.

| **No.** | **Position** | **Variant** | **Family ID** | **Nationality** | **Diseases** | **Unaffected Maternal Relatives** | **Affected Maternal Relatives** | **Publication Year** | **PMID/Ref** | **Note** |
| --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- |
| 1 | 1659 | m.1659T\>C |[ T1659C\-F1 ](https://mitofam.com/doc/861/)| UK | Childhood\-onset encephalopathy, learning difficulties, hemiplegia, movement disorder(dystonia), ichthyosis, hypertrophic cardiomyopathy, bilateral putaminal lesions | ND | ND | 2004 | [15465092](https://pubmed.ncbi.nlm.nih.gov/15465092/) |  |
| 2 | 1659 | m.1659T\>C | T1659C\-F2 | Ireland | Late\-onset encephalopathy | ND | ND | 2024 | [38973423](https://pubmed.ncbi.nlm.nih.gov/38973423/) |  |

# 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 | 1659 | m.1659T\>C | T1659C\-F1 | T1659C\-F1\-II1 | Fam | F | Y | Y | A | 13 | 98% | 98% | 99% | 99%(BM) | Childhood\-onset encephalopathy, learning difficulties, hemiplegia, movement disorder(dystonia), ichthyosis, hypertrophic cardiomyopathy, bilateral putaminal lesions |  |
| 2 | 1659 | m.1659T\>C | T1659C\-F1 | T1659C\-F1\-I2 | Uninf | F | N | N | A | ND | 7% | / | / | 19%(BM) | Healthy |  |
| 3 | 1659 | m.1659T\>C | T1659C\-F2 | T1659C\-F2\-Ⅱ\-2 | Uninf | M | Y | Y | A | 67 | 59% | 91% | 71% | 45%(BM) | Late\-onset encephalopathy, seizures, ataxia, weight loss, sensorineural hearing loss, end\-stage kidney disease(requiring haemodialysis), cerebellar atrophy |  |

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