T8993C

# **General Information**

| **Position** | **8993** | **Variant** | **m.8993T\>C** | **Locus** | **MT\-ATP6** | **Amino\-AcidChange** | **L156P** |
| --- | --- | --- | --- | --- | --- | --- | --- |
| **Homoplasmy** | \- | **Heteroplasmy** | \+ | **APOGEE2** | Pathogenic | **Pathogenicity** | Cfrm \[P] |

"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**
# **General Information**

| **Position** | **8993** | **Variant** | **m.8993T\>C** | **Locus** | **MT\-ATP6** | **Amino\-AcidChange** | **L156P** |
| --- | --- | --- | --- | --- | --- | --- | --- |
| **Homoplasmy** | \- | **Heteroplasmy** | \+ | **APOGEE2** | Pathogenic | **Pathogenicity** | Cfrm \[P] |

"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.8993T\>C** variant in MT\-ATP6 has been reported in 6 pedigrees. To date, 38 carriers have been reported. Homoplasmy was reported in 1/38 carriers (2\.6%), and 17/38 carriers (44\.7%) were affected. The main clinical manifestations among affected carriers included leigh syndrome, mental retardation, extrapyramidal and cerebellar signs, pyramidal, adult\-onset ataxia, axonal sensorimotor neuropathy, cerebellar atrophy, eye, and other features.

| **No.** | **Position** | **Variant** | **Family ID** | **Nationality** | **Diseases** | **Unaffected Maternal Relatives** | **Affected Maternal Relatives** | **Publication Year** | **PMID/Ref** | **Note** |
| --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- |
| 1 | 8993 | m.8993T\>C |[ T8993C\-F4](https://mitofam.com/doc/1689/) | Finnish | Adult\-onset ataxia and axonal polyneuropathy | 2 | 3 | 2005 | [16049925](https://pubmed.ncbi.nlm.nih.gov/16049925/) |  |
| 2 | 8993 | m.8993T\>C | [T8993C\-F5](https://mitofam.com/doc/1690/) | Italian | NARP; MILS\-compatible deceased sibling | 0 | 2 | 2007 | [17568559](https://pubmed.ncbi.nlm.nih.gov/17568559/) |  |
| 3 | 8993 | m.8993T\>C | [T8993C\-F6](https://mitofam.com/doc/1691/) | UK | Adult\-onset ataxia and polyneuropathy; episodic ataxia | 0 | 2 | 2007 | [18055910](https://pubmed.ncbi.nlm.nih.gov/18055910/) |  |
| 4 | 8993 | m.8993T\>C | [T8993C\-F7 ](https://mitofam.com/doc/1692/)| Vietnam | Leigh syndrome | 5 | 0 | 2018 | [29512743](https://pubmed.ncbi.nlm.nih.gov/29512743/) |  |
| 5 | 8993 | m.8993T\>C | [T8993C\-F8](https://mitofam.com/doc/1693/) | USA | Leigh syndrome | 13 | 0 | 1994 | [8190310](https://pubmed.ncbi.nlm.nih.gov/8190310/) |  |
| 6 | 8993 | m.8993T\>C | [T8993C\-F9](https://mitofam.com/doc/1694/) | Netherlands | Leigh syndrome | 0 | 4 | 1993 | [8395787](https://pubmed.ncbi.nlm.nih.gov/8395787/) |  |

# **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 | 8993 | m.8993T\>C | T8993C\-F4 | T8993C\-F4\-II6 | Fam | F | N | N | A | 89 y | 59% | / | / | / | Healthy; no neuromuscular symptoms reported |  |
| 2 | 8993 | m.8993T\>C | T8993C\-F4 | T8993C\-F4\-III1 | Fam | F | N | N | A | 35 | 28% | / | / | / | Multiple sclerosis diagnosis; low heteroplasmy considered independent cause |  |
| 3 | 8993 | m.8993T\>C | T8993C\-F4 | T8993C\-F4\-III3 | Fam | M | N | Y | A | 65 y | 79% | / | / | / | Adult\-onset axonal sensorimotor polyneuropathy, gait difficulty, mild ataxia |  |
| 4 | 8993 | m.8993T\>C | T8993C\-F4 | T8993C\-F4\-III5 | Fam | M | N | Y | A | 58 y | 64% | / | / | / | Adult\-onset ataxia, dysarthria, axonal sensorimotor neuropathy |  |
| 5 | 8993 | m.8993T\>C | T8993C\-F4 | T8993C\-F4\-III6 | Fam | F | Y | Y | A | 52 y | 89% | / | / | / | Adult\-onset ataxia, seizures/drop attacks, axonal sensorimotor polyneuropathy, mild muscle weakness |  |
| 6 | 8993 | m.8993T\>C | T8993C\-F4 | T8993C\-F4\-III4 | Fam | F | N | Y | D | 22 y | / | / | / | / | Early\-onset ataxic gait; limb dysmetria; high\-arched feet; reduced lower\-limb strength; moderate mental impairment; seizures; lethargy/coma; autopsy compatible with Friedreich's ataxia |  |
| 7 | 8993 | m.8993T\>C | T8993C\-F5 | T8993C\-F5\-I1 | Uninf | F | N | Y | A | 53 y | 30% | / | / | / | Short stature; mild peripheral neuropathy |  |
| 8 | 8993 | m.8993T\>C | T8993C\-F5 | T8993C\-F5\-II1 | Fam | F | Y | Y | A | 30 y | 94% | / | / | / | NARP; visual loss from retinitis pigmentosa, sensorineural deafness, cerebellar ataxia, muscle weakness, mild mental retardation |  |
| 9 | 8993 | m.8993T\>C | T8993C\-F5 | T8993C\-F5\-II2 | Fam | F | N | Y | D | 3 y | / | / | / | / | Encephalopathic features compatible with Leigh syndrome |  |
| 10 | 8993 | m.8993T\>C | T8993C\-F6 | T8993C\-F6\-I1 | Uninf | F | N | Y | A | 76 y | 86% | / | / | / | Adult\-onset gait ataxia, cerebellar dysarthria, nystagmus, mild axonal sensorimotor neuropathy, cerebellar atrophy |  |
| 11 | 8993 | m.8993T\>C | T8993C\-F6 | T8993C\-F6\-II1 | Fam | F | Y | Y | A | 50 y | 82% | / | / | / | Intermittent speech and gait disturbance, childhood hemipareses, headaches, neuropathy, ataxic gait |  |
| 12 | 8993 | m.8993T\>C | T8993C\-F6 | T8993C\-F6\-III1 | Fam | F | N | Y | A | 25 y | 83% | / | / | / | Episodic gait disturbance, progressive dysarthria, optic atrophy, axonal sensorimotor neuropathy, cerebellar atrophy |  |
| 13 | 8993 | m.8993T\>C | T8993C\-F7 | T8993C\-F7\-III1 | Fam | M | Y | Y | D | 21mo | 94% | / | / | / | Leigh syndrome; epilepsy; hypotonia; vomiting; abnormal brain MRI |  |
| 14 | 8993 | m.8993T\>C | T8993C\-F7 | T8993C\-F7\-II2 | Fam | F | N | N | A | 32 | 71\.66% | / | / | / | Healthy |  |
| 15 | 8993 | m.8993T\>C | T8993C\-F7 | T8993C\-F7\-II3 | Fam | F | N | N | A | ND | 66\.81% | / | / | / | Healthy |  |
| 16 | 8993 | m.8993T\>C | T8993C\-F7 | T8993C\-F7\-III2 | Fam | M | N | N | A | ND | 87% | / | / | / | Healthy |  |
| 17 | 8993 | m.8993T\>C | T8993C\-F7 | T8993C\-F7\-III3 | Fam | F | N | N | A | ND | 91\.24% | / | / | / | Healthy |  |
| 18 | 8993 | m.8993T\>C | T8993C\-F7 | T8993C\-F7\-I2 | Uninf | F | N | N | A | ND | 16\.33% | / | / | / | Healthy |  |
| 19 | 8993 | m.8993T\>C | T8993C\-F8 | T8993C\-F8\-I1 | Uninf | F | N | N | A | ND | 7% | / | / | / | Healthy |  |
| 20 | 8993 | m.8993T\>C | T8993C\-F8 | T8993C\-F8\-II1 | Fam | F | N | N | A | ND | 39% | / | / | / | Healthy |  |
| 21 | 8993 | m.8993T\>C | T8993C\-F8 | T8993C\-F8\-II2 | Fam | F | N | N | A | ND | 52% | / | / | / | Healthy |  |
| 22 | 8993 | m.8993T\>C | T8993C\-F8 | T8993C\-F8\-II3 | Fam | F | N | N | A | ND | 5% | / | / | / | Healthy |  |
| 23 | 8993 | m.8993T\>C | T8993C\-F8 | T8993C\-F8\-II4 | Fam | F | N | N | A | ND | 8% | / | / | / | Healthy |  |
| 24 | 8993 | m.8993T\>C | T8993C\-F8 | T8993C\-F8\-II5 | Fam | F | N | N | A | ND | 2% | / | / | / | Healthy |  |
| 25 | 8993 | m.8993T\>C | T8993C\-F8 | T8993C\-F8\-II6 | Fam | F | N | N | A | ND | 4% | / | / | / | Healthy |  |
| 26 | 8993 | m.8993T\>C | T8993C\-F8 | T8993C\-F8\-III1 | Fam | F | N | N | A | ND | 88% | / | / | / | Normal neurologic exam; unsteadiness and poor endurance |  |
| 27 | 8993 | m.8993T\>C | T8993C\-F8 | T8993C\-F8\-III2 | Fam | F | N | N | A | ND | 25% | / | / | / | Healthy |  |
| 28 | 8993 | m.8993T\>C | T8993C\-F8 | T8993C\-F8\-III3 | Fam | M | N | N | A | ND | 28% | / | / | / | Healthy |  |
| 29 | 8993 | m.8993T\>C | T8993C\-F8 | T8993C\-F8\-III4 | Fam | F | N | N | A | ND | 44% | / | / | / | Healthy |  |
| 30 | 8993 | m.8993T\>C | T8993C\-F8 | T8993C\-F8\-IV1 | Fam | M | Y | Y | A | 5 y | \>90% | \>90% | / | \>90%(F) | Leigh syndrome; developmental delay; hypotonia; severe ataxia; basal ganglia lesions; respiratory difficulty with ventilator dependence; normal blood lactate and urine organic acids |  |
| 31 | 8993 | m.8993T\>C | T8993C\-F8 | T8993C\-F8\-IV2 | Fam | F | N | N | A | ND | 66% | / | / | / | Healthy |  |
| 32 | 8993 | m.8993T\>C | T8993C\-F8 | T8993C\-F8\-IV3 | Fam | M | N | ND | D | ND | / | / | / | 59%(Skin); 59%(LUNG); 59%(Liver) | Miscarried male fetus |  |
| 33 | 8993 | m.8993T\>C | T8993C\-F8 | T8993C\-F8\-IV4 | Fam | M | N | N | A | ND | 90% | / | / | / | Healthy |  |
| 34 | 8993 | m.8993T\>C | T8993C\-F9 | T8993C\-F9\-I1 | Uninf | F | N | Y | A | 56 y onset | \+ | / | / | / | Leigh syndrome; weakness, fatigability, sensory disturbances; pyramidal and cerebellar signs |  |
| 35 | 8993 | m.8993T\>C | T8993C\-F9 | T8993C\-F9\-II2 | Fam | M | N | Y | A | 3 y onset | \+ | \~homo | / | / | Leigh syndrome; mental retardation; pyramidal, extrapyramidal and cerebellar signs; putamen and cerebellar MRI abnormalities |  |
| 36 | 8993 | m.8993T\>C | T8993C\-F9 | T8993C\-F9\-II3 | Fam | F | N | Y | A | 9 y onset | \+ | / | / | / | Leigh syndrome; mental retardation; eye, pyramidal and cerebellar signs; brainstem MRI abnormalities |  |
| 37 | 8993 | m.8993T\>C | T8993C\-F9 | T8993C\-F9\-II4 | Fam | F | N | Y | A | 4 y onset | \+ | / | / | / | Leigh syndrome; mental retardation; eye, pyramidal, extrapyramidal and cerebellar signs; cerebellar MRI abnormalities |  |
| 38 | 8993 | m.8993T\>C | T8993C\-F9 | T8993C\-F9\-II1 | Fam | M | N | Y | D | 6 y onset; died 17 y | / | / | / | / | Leigh syndrome; mental retardation; eye signs; pyramidal, extrapyramidal and cerebellar signs |  |

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

The **m.8993T\>C** variant in MT\-ATP6 has been reported in 6 pedigrees. To date, 38 carriers have been reported. Homoplasmy was reported in 1/38 carriers (2\.6%), and 17/38 carriers (44\.7%) were affected. The main clinical manifestations among affected carriers included leigh syndrome, mental retardation, extrapyramidal and cerebellar signs, pyramidal, adult\-onset ataxia, axonal sensorimotor neuropathy, cerebellar atrophy, eye, and other features.

| **No.** | **Position** | **Variant** | **Family ID** | **Nationality** | **Diseases** | **Unaffected Maternal Relatives** | **Affected Maternal Relatives** | **Publication Year** | **PMID/Ref** | **Note** |
| --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- |
| 1 | 8993 | m.8993T\>C | T8993C\-F4 | Finnish | Adult\-onset ataxia and axonal polyneuropathy | 2 | 3 | 2005 | [16049925](https://pubmed.ncbi.nlm.nih.gov/16049925/) |  |
| 2 | 8993 | m.8993T\>C | T8993C\-F5 | Italian | NARP; MILS\-compatible deceased sibling | 0 | 2 | 2007 | [17568559](https://pubmed.ncbi.nlm.nih.gov/17568559/) |  |
| 3 | 8993 | m.8993T\>C | T8993C\-F6 | UK | Adult\-onset ataxia and polyneuropathy; episodic ataxia | 0 | 2 | 2007 | [18055910](https://pubmed.ncbi.nlm.nih.gov/18055910/) |  |
| 4 | 8993 | m.8993T\>C | T8993C\-F7 | Vietnam | Leigh syndrome | 5 | 0 | 2018 | [29512743](https://pubmed.ncbi.nlm.nih.gov/29512743/) |  |
| 5 | 8993 | m.8993T\>C | T8993C\-F8 | USA | Leigh syndrome | 13 | 0 | 1994 | [8190310](https://pubmed.ncbi.nlm.nih.gov/8190310/) |  |
| 6 | 8993 | m.8993T\>C | T8993C\-F9 | Netherlands | Leigh syndrome | 0 | 4 | 1993 | [8395787](https://pubmed.ncbi.nlm.nih.gov/8395787/) |  |

# **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 | 8993 | m.8993T\>C | T8993C\-F4 | T8993C\-F4\-II6 | Fam | F | N | N | A | 89 y | 59% | / | / | / | Healthy; no neuromuscular symptoms reported |  |
| 2 | 8993 | m.8993T\>C | T8993C\-F4 | T8993C\-F4\-III1 | Fam | F | N | N | A | 35 | 28% | / | / | / | Multiple sclerosis diagnosis; low heteroplasmy considered independent cause |  |
| 3 | 8993 | m.8993T\>C | T8993C\-F4 | T8993C\-F4\-III3 | Fam | M | N | Y | A | 65 y | 79% | / | / | / | Adult\-onset axonal sensorimotor polyneuropathy, gait difficulty, mild ataxia |  |
| 4 | 8993 | m.8993T\>C | T8993C\-F4 | T8993C\-F4\-III5 | Fam | M | N | Y | A | 58 y | 64% | / | / | / | Adult\-onset ataxia, dysarthria, axonal sensorimotor neuropathy |  |
| 5 | 8993 | m.8993T\>C | T8993C\-F4 | T8993C\-F4\-III6 | Fam | F | Y | Y | A | 52 y | 89% | / | / | / | Adult\-onset ataxia, seizures/drop attacks, axonal sensorimotor polyneuropathy, mild muscle weakness |  |
| 6 | 8993 | m.8993T\>C | T8993C\-F4 | T8993C\-F4\-III4 | Fam | F | N | Y | D | 22 y | / | / | / | / | Early\-onset ataxic gait; limb dysmetria; high\-arched feet; reduced lower\-limb strength; moderate mental impairment; seizures; lethargy/coma; autopsy compatible with Friedreich's ataxia |  |
| 7 | 8993 | m.8993T\>C | T8993C\-F5 | T8993C\-F5\-I1 | Uninf | F | N | Y | A | 53 y | 30% | / | / | / | Short stature; mild peripheral neuropathy |  |
| 8 | 8993 | m.8993T\>C | T8993C\-F5 | T8993C\-F5\-II1 | Fam | F | Y | Y | A | 30 y | 94% | / | / | / | NARP; visual loss from retinitis pigmentosa, sensorineural deafness, cerebellar ataxia, muscle weakness, mild mental retardation |  |
| 9 | 8993 | m.8993T\>C | T8993C\-F5 | T8993C\-F5\-II2 | Fam | F | N | Y | D | 3 y | / | / | / | / | Encephalopathic features compatible with Leigh syndrome |  |
| 10 | 8993 | m.8993T\>C | T8993C\-F6 | T8993C\-F6\-I1 | Uninf | F | N | Y | A | 76 y | 86% | / | / | / | Adult\-onset gait ataxia, cerebellar dysarthria, nystagmus, mild axonal sensorimotor neuropathy, cerebellar atrophy |  |
| 11 | 8993 | m.8993T\>C | T8993C\-F6 | T8993C\-F6\-II1 | Fam | F | Y | Y | A | 50 y | 82% | / | / | / | Intermittent speech and gait disturbance, childhood hemipareses, headaches, neuropathy, ataxic gait |  |
| 12 | 8993 | m.8993T\>C | T8993C\-F6 | T8993C\-F6\-III1 | Fam | F | N | Y | A | 25 y | 83% | / | / | / | Episodic gait disturbance, progressive dysarthria, optic atrophy, axonal sensorimotor neuropathy, cerebellar atrophy |  |
| 13 | 8993 | m.8993T\>C | T8993C\-F7 | T8993C\-F7\-III1 | Fam | M | Y | Y | D | 21mo | 94% | / | / | / | Leigh syndrome; epilepsy; hypotonia; vomiting; abnormal brain MRI |  |
| 14 | 8993 | m.8993T\>C | T8993C\-F7 | T8993C\-F7\-II2 | Fam | F | N | N | A | 32 | 71\.66% | / | / | / | Healthy |  |
| 15 | 8993 | m.8993T\>C | T8993C\-F7 | T8993C\-F7\-II3 | Fam | F | N | N | A | ND | 66\.81% | / | / | / | Healthy |  |
| 16 | 8993 | m.8993T\>C | T8993C\-F7 | T8993C\-F7\-III2 | Fam | M | N | N | A | ND | 87% | / | / | / | Healthy |  |
| 17 | 8993 | m.8993T\>C | T8993C\-F7 | T8993C\-F7\-III3 | Fam | F | N | N | A | ND | 91\.24% | / | / | / | Healthy |  |
| 18 | 8993 | m.8993T\>C | T8993C\-F7 | T8993C\-F7\-I2 | Uninf | F | N | N | A | ND | 16\.33% | / | / | / | Healthy |  |
| 19 | 8993 | m.8993T\>C | T8993C\-F8 | T8993C\-F8\-I1 | Uninf | F | N | N | A | ND | 7% | / | / | / | Healthy |  |
| 20 | 8993 | m.8993T\>C | T8993C\-F8 | T8993C\-F8\-II1 | Fam | F | N | N | A | ND | 39% | / | / | / | Healthy |  |
| 21 | 8993 | m.8993T\>C | T8993C\-F8 | T8993C\-F8\-II2 | Fam | F | N | N | A | ND | 52% | / | / | / | Healthy |  |
| 22 | 8993 | m.8993T\>C | T8993C\-F8 | T8993C\-F8\-II3 | Fam | F | N | N | A | ND | 5% | / | / | / | Healthy |  |
| 23 | 8993 | m.8993T\>C | T8993C\-F8 | T8993C\-F8\-II4 | Fam | F | N | N | A | ND | 8% | / | / | / | Healthy |  |
| 24 | 8993 | m.8993T\>C | T8993C\-F8 | T8993C\-F8\-II5 | Fam | F | N | N | A | ND | 2% | / | / | / | Healthy |  |
| 25 | 8993 | m.8993T\>C | T8993C\-F8 | T8993C\-F8\-II6 | Fam | F | N | N | A | ND | 4% | / | / | / | Healthy |  |
| 26 | 8993 | m.8993T\>C | T8993C\-F8 | T8993C\-F8\-III1 | Fam | F | N | N | A | ND | 88% | / | / | / | Normal neurologic exam; unsteadiness and poor endurance |  |
| 27 | 8993 | m.8993T\>C | T8993C\-F8 | T8993C\-F8\-III2 | Fam | F | N | N | A | ND | 25% | / | / | / | Healthy |  |
| 28 | 8993 | m.8993T\>C | T8993C\-F8 | T8993C\-F8\-III3 | Fam | M | N | N | A | ND | 28% | / | / | / | Healthy |  |
| 29 | 8993 | m.8993T\>C | T8993C\-F8 | T8993C\-F8\-III4 | Fam | F | N | N | A | ND | 44% | / | / | / | Healthy |  |
| 30 | 8993 | m.8993T\>C | T8993C\-F8 | T8993C\-F8\-IV1 | Fam | M | Y | Y | A | 5 y | \>90% | \>90% | / | \>90%(F) | Leigh syndrome; developmental delay; hypotonia; severe ataxia; basal ganglia lesions; respiratory difficulty with ventilator dependence; normal blood lactate and urine organic acids |  |
| 31 | 8993 | m.8993T\>C | T8993C\-F8 | T8993C\-F8\-IV2 | Fam | F | N | N | A | ND | 66% | / | / | / | Healthy |  |
| 32 | 8993 | m.8993T\>C | T8993C\-F8 | T8993C\-F8\-IV3 | Fam | M | N | ND | D | ND | / | / | / | 59%(Skin); 59%(LUNG); 59%(Liver) | Miscarried male fetus |  |
| 33 | 8993 | m.8993T\>C | T8993C\-F8 | T8993C\-F8\-IV4 | Fam | M | N | N | A | ND | 90% | / | / | / | Healthy |  |
| 34 | 8993 | m.8993T\>C | T8993C\-F9 | T8993C\-F9\-I1 | Uninf | F | N | Y | A | 56 y onset | \+ | / | / | / | Leigh syndrome; weakness, fatigability, sensory disturbances; pyramidal and cerebellar signs |  |
| 35 | 8993 | m.8993T\>C | T8993C\-F9 | T8993C\-F9\-II2 | Fam | M | N | Y | A | 3 y onset | \+ | \~homo | / | / | Leigh syndrome; mental retardation; pyramidal, extrapyramidal and cerebellar signs; putamen and cerebellar MRI abnormalities |  |
| 36 | 8993 | m.8993T\>C | T8993C\-F9 | T8993C\-F9\-II3 | Fam | F | N | Y | A | 9 y onset | \+ | / | / | / | Leigh syndrome; mental retardation; eye, pyramidal and cerebellar signs; brainstem MRI abnormalities |  |
| 37 | 8993 | m.8993T\>C | T8993C\-F9 | T8993C\-F9\-II4 | Fam | F | N | Y | A | 4 y onset | \+ | / | / | / | Leigh syndrome; mental retardation; eye, pyramidal, extrapyramidal and cerebellar signs; cerebellar MRI abnormalities |  |
| 38 | 8993 | m.8993T\>C | T8993C\-F9 | T8993C\-F9\-II1 | Fam | M | N | Y | D | 6 y onset; died 17 y | / | / | / | / | Leigh syndrome; mental retardation; eye signs; pyramidal, extrapyramidal and cerebellar signs |  |

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