T9998C

# **General Information**

| **Position** | **9998** | **Variant** | **m.9998T\>C** | **Locus** | **MT\-TG** | **RNA** | **tRNA Gly** |
| --- | --- | --- | --- | --- | --- | --- | --- |
| **Homoplasmy** | \- | **Heteroplasmy** | \+ | **mitoTIP** | 40\.10% | **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.9998T\>C** variant in MT\-TG has been reported in 1 pedigree. To date, 1 carrier has been reported. Reported mutation loads ranged from 21% to 97%, with a median of 76\.6% overall; affected carriers showed mutation loads from 21% to 97%, with a median of 76\.6%. In one affected carrier, a marked tissue\-specific difference was observed, with higher mutation loads in muscle (97%) and urine (76\.6%) than in blood (21%). The main clinical manifestations among affected carriers included exercise intolerance, behavioral disorder, cataract, cognitive disorder, deafness, diabetes insipidus, epilepsy, growth delay, and other features.

| **No.** | **Position** | **Variant** | **Family ID** | **Nationality** | **Diseases** | **Unaffected Maternal Relatives** | **Affected Maternal Relatives** | **Publication Year** | **PMID/Ref** | **Note** |
| --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- |
| 1 | 9998 | m.9998T\>C | T9998C\-F1 | France | Exercise intolerance, cataract, optic neuropathy, deafness, growth delay, hypogonadism, diabetes insipidus, behavioral disorder, cognitive disorder, recurrent coma, lactic acidosis, epilepsy, status epilepticus | 0 | 0 | 2025 | [https://www.medrxiv.org/content/10\.1101/2025\.11\.19\.25339649v1\.full](https://www.medrxiv.org/content/10.1101/2025.11.19.25339649v1.full) |  |

# **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 | 9998 | m.9998T\>C | T9998C\-F1 | T9998C\-F1\-P1 | De novo | M | Y | Y | D | 35\-40 | 21% | 97% | 76\.6% | / | Exercise intolerance, cataract, optic neuropathy, deafness, growth delay, hypogonadism, diabetes insipidus, behavioral disorder, cognitive disorder, recurrent coma, lactic acidosis, epilepsy, status epilepticus |  |

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