T14674C

# General Information

| **Position** | **14674** | **Variant** | **m.14674T\>C** | **Locus** | **MT\-TE** | **RNA** | **tRNA Glu** |
| --- | --- | --- | --- | --- | --- | --- | --- |
| **Homoplasmy** | \+ | **Heteroplasmy** | \- | **mitoTIP** | Pathogenic | **Pathogenicity** | Cfrm \[LP] |

"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.14674T\>C variant in MT\-TE has been reported in 18 pedigrees. To date, 47 carriers have been reported. Homoplasmy was reported in 40/47 carriers (85\.1%), and 30/47 carriers (63\.8%) were affected. The main clinical manifestations among affected carriers included No specific clinical features were available for affected carriers.

| **No.** | **Position** | **Variant** | **Family ID** | **Nationality** | **Diseases** | **Unaffected Maternal Relatives** | **Affected Maternal Relatives** | **Publication Year** | **PMID/Ref** | **Note** |
| --- | --- | --- | --- | --- | --- | --- | --- | --- | --- | --- |
| 1 | 14674 | m.14674T\>C | [T14674C\-F1](https://mitofam.com/doc/939/) | UK | Myopathy | 6 | 2 | 2009 | [19720722](https://pubmed.ncbi.nlm.nih.gov/19720722/) |  |
| 2 | 14674 | m.14674T\>C |[ T14674C\-F2 ](https://mitofam.com/doc/940/)| UK | Myopathy | 2 | 0 | 2009 | [19720722](https://pubmed.ncbi.nlm.nih.gov/19720722/) |  |
| 3 | 14674 | m.14674T\>C | [T14674C\-F3](https://mitofam.com/doc/941/) | UK | Myopathy | 5 | 0 | 2009 | [19720722](https://pubmed.ncbi.nlm.nih.gov/19720722/) |  |
| 4 | 14674 | m.14674T\>C | T14674C\-F4 | Japan | Poor sucking, congenital myopathy | 0 | 0 | 2010 | [21194154](https://pubmed.ncbi.nlm.nih.gov/21194154/) |  |
| 5 | 14674 | m.14674T\>C | T14674C\-F5 | Japan | Failure to thrive, mitochondrial myopathy | 0 | 0 | 2010 | [21194154](https://pubmed.ncbi.nlm.nih.gov/21194154/) |  |
| 6 | 14674 | m.14674T\>C | T14674C\-F6 | Japan | Failure to thrive, mitochondrial myopathy, febrile convulsion | 0 | 0 | 2010 | [21194154](https://pubmed.ncbi.nlm.nih.gov/21194154/) |  |
| 7 | 14674 | m.14674T\>C | T14674C\-F7 | Japan | Floppy infant, congenital muscular dystrophy | 1 | 0 | 2010 | [21194154](https://pubmed.ncbi.nlm.nih.gov/21194154/) |  |
| 8 | 14674 | m.14674T\>C | T14674C\-F8 | Japan | Poor sucking, floppy infant, mitochondrial myopathy, bilateral basal ganglia lesions | 0 | 0 | 2010 | [21194154](https://pubmed.ncbi.nlm.nih.gov/21194154/) |  |
| 9 | 14674 | m.14674T\>C | T14674C\-F9 | UK | Feeding difficulties, hypotonia | ND | ND | 2011 | [21931168](https://pubmed.ncbi.nlm.nih.gov/21931168/) |  |
| 10 | 14674 | m.14674T\>C | T14674C\-F10 | UK | Feeding and respiratory difficulties, hypotonia, hepatomegaly | ND | ND | 2011 | [21931168](https://pubmed.ncbi.nlm.nih.gov/21931168/) |  |
| 11 | 14674 | m.14674T\>C | [T14674C\-F11](https://mitofam.com/doc/942/) | Italy | Feeding and respiratory difficulties | ND | ND | 2011 | [21931168](https://pubmed.ncbi.nlm.nih.gov/21931168/) |  |
| 12 | 14674 | m.14674T\>C | T14674C\-F12 | Turkey | Feeding difficulties, hypotonia | ND | ND | 2011 | [21931168](https://pubmed.ncbi.nlm.nih.gov/21931168/) |  |
| 13 | 14674 | m.14674T\>C | T14674C\-F13 | Brazil | Profound hypotonia,cervical weakness, and feeding difficulties | 1 | 0 | 2021 | [33832841](https://pubmed.ncbi.nlm.nih.gov/33832841/) | Carrying QRSL1 c.686T\>G; p.Val299Gly |
| 14 | 14674 | m.14674T\>C | T14674C\-F14 | Brazil | Fever, adynamia, and feeding difficulties | 4 | 0 | 2021 | [33832841](https://pubmed.ncbi.nlm.nih.gov/33832841/) | Carrying EARS2 c.358C\>T |
| 15 | 14674 | m.14674T\>C | [T14674C\-F15](https://mitofam.com/doc/943/) | Sweden | Infantile vomiting, feeding difficulty,failure to thrive, pneumonia, sepsis, hypotonia, muscle weakness, dysphagia | 2 | 0 | 2022 | [34806237](https://pubmed.ncbi.nlm.nih.gov/34806237/) |  |
| 16 | 14674 | m.14674T\>C | [T14674C\-F16 ](https://mitofam.com/doc/944/)| Sweden | Irritability, lethargy, hypotonia, feeding difficulties, failure to thrive, mild liver involvement, respiratory infection, respiratory failure, dysphagia | 2 | 2 | 2022 | [34806237](https://pubmed.ncbi.nlm.nih.gov/34806237/) |  |
| 17 | 14674 | m.14674T\>C | [T14674C\-F17](https://mitofam.com/doc/945/) | Sweden | Poor feeding, vomiting, failure to thrive, severe muscular hypotonia, swallowing difficulties | 1 | 0 | 2022 | [34806237](https://pubmed.ncbi.nlm.nih.gov/34806237/) |  |
| 18 | 14674 | m.14674T\>C |[ T14674C\-F18](https://mitofam.com/doc/946/) | Sweden | Gait instability, poor balance, leg pain, muscle fatigue, feeding difficulty, thin stature, mild cognitive impairment, hypotonia, areflexia, joint contractures, swallowing difficulty, respiratory infection, motor delay | 3 | 1 | 2022 | [34806237](https://pubmed.ncbi.nlm.nih.gov/34806237/) |  |

# 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 | 14674 | m.14674T\>C | T14674C\-F1 | T14674C\-F1\-II8 | Fam | M | Y | Y | A | 22 months | Homo | Homo | / | / | hypotonia, myopathy, ventilator\-dependent, tube\-feeding, hepatic involvement, reversible weakness, residual myopathy |  |
| 2 | 14674 | m.14674T\>C | T14674C\-F1 | T14674C\-F1\-I2 | Uninf | F | N | Y | A | ND | / | Homo | / | / | mild motor developmental delay, anaemia, poor weight gain |  |
| 3 | 14674 | m.14674T\>C | T14674C\-F1 | T14674C\-F1\-II7 | Fam | F | N | Y | A | ND | Homo | / | / | / | anaemia, poor weight gain |  |
| 4 | 14674 | m.14674T\>C | T14674C\-F2 | T14674C\-F2\-II1 | Fam | M | Y | Y | A | 22 | Homo | Homo | / | / | hypotonia, myopathy, tube\-feeding, hepatic involvement, persistent proximal myopathy |  |
| 5 | 14674 | m.14674T\>C | T14674C\-F2 | T14674C\-F2\-III1 | Fam | M | Y | Y | A | 7 | Homo | Homo | / | / | hypotonia, ventilator\-dependent, tube\-feeding, hepatic involvement, complete recovery |  |
| 6 | 14674 | m.14674T\>C | T14674C\-F2 | T14674C\-F2\-I2 | Uninf | F | N | N | A | ND | Homo | / | / | / | Healthy |  |
| 7 | 14674 | m.14674T\>C | T14674C\-F3 | T14674C\-F3\-III1 | Fam | M | Y | Y | A | 11 | Homo | Homo | / | / | severe hypotonia, ventilator\-dependent, tube\-feeding, liver dysfunction, myopathic facies, scapular winging, residual myopathy |  |
| 8 | 14674 | m.14674T\>C | T14674C\-F3 | T14674C\-F3\-III2 | Fam | M | Y | Y | A | 9 | Homo | Homo | / | / | hypotonia, ventilator\-dependent, tube\-feeding, hepatic involvement, complete recovery |  |
| 9 | 14674 | m.14674T\>C | T14674C\-F3 | T14674C\-F3\-II5 | Fam | F | Y | Y | A | 26 | Homo | Homo | / | / | hypotonia, tube\-feeding, hepatic involvement, complete recovery |  |
| 10 | 14674 | m.14674T\>C | T14674C\-F3 | T14674C\-F3\-II6 | Fam | M | Y | Y | A | 26 | Homo | Homo | / | / | hypotonia, tube\-feeding, hepatic involvement, complete recovery |  |
| 11 | 14674 | m.14674T\>C | T14674C\-F3 | T14674C\-F3\-II2 | Fam | F | N | N | A | ND | Homo | / | / | / | Healthy |  |
| 12 | 14674 | m.14674T\>C | T14674C\-F4 | T14674C\-F4\-P1 | Uninf | F | Y | Y | A | 5 months | / | Homo | / | / | Poor sucking, congenital myopathy |  |
| 13 | 14674 | m.14674T\>C | T14674C\-F5 | T14674C\-F5\-P1 | Uninf | F | Y | Y | A | 3 months | / | Homo | / | / | Failure to thrive, mitochondrial myopathy |  |
| 14 | 14674 | m.14674T\>C | T14674C\-F6 | T14674C\-F6\-P1 | Uninf | M | Y | Y | A | 4 months | / | Homo | / | / | Failure to thrive, febrile convulsion, mitochondrial myopathy |  |
| 15 | 14674 | m.14674T\>C | T14674C\-F7 | T14674C\-F7\-P1 | Uninf | M | Y | Y | A | 9 months | / | Homo | / | / | Floppy infant, congenital muscular dystrophy |  |
| 16 | 14674 | m.14674T\>C | T14674C\-F8 | T14674C\-F8\-P1 | Fam | F | Y | Y | A | ND | Homo | / | / | / | Poor sucking, mitochondrial myopathy, bilateral basal ganglia lesions |  |
| 17 | 14674 | m.14674T\>C | T14674C\-F8 | T14674C\-F8\-P2 | Fam | M | Y | Y | A | ND | Homo | / | / | / | Floppy infant, mitochondrial myopathy, bilateral basal ganglia lesions |  |
| 18 | 14674 | m.14674T\>C | T14674C\-F9 | T14674C\-F9\-P1 | Fam | ND | Y | Y | A | 35 | Homo | / | / | Homo (saliva) | Feeding difficulties,hypotonia |  |
| 19 | 14674 | m.14674T\>C | T14674C\-F9 | T14674C\-F9\-P2 | Fam | ND | Y | Y | A | 13 | Homo | / | / | Homo (saliva) | Feeding difficulties,hypotonia |  |
| 20 | 14674 | m.14674T\>C | T14674C\-F10 | T14674C\-F10\-P1 | Uninf | M | Y | Y | A | 22 | Homo | / | / | Homo (saliva) | Feeding and respiratory difficulties,hypotonia,hepatomegaly |  |
| 21 | 14674 | m.14674T\>C | T14674C\-F11 | T14674C\-F11\-II1 | Fam | F | Y | Y | A | 15 | Homo | / | / | Homo (saliva) | Feeding and respiratory difficulties |  |
| 22 | 14674 | m.14674T\>C | T14674C\-F11 | T14674C\-F11\-I2 | Uninf | F | N | Y | A | ND | / | / | / | Homo (tissue not specified) | Mild facial weakness |  |
| 23 | 14674 | m.14674T\>C | T14674C\-F12 | T14674C\-F12\-P1 | Uninf | F | Y | Y | A | 4 | Homo | / | / | Homo (saliva) | Feeding difficulties,hypotonia |  |
| 24 | 14674 | m.14674T\>C | T14674C\-F13 | T14674C\-F13\-P1 | Fam | M | Y | Y | A | 1 month | Homo | / | / | / | Profound hypotonia,cervical weakness, and feeding difficulties | Carrying QRSL1 c.686T\>G; p.Val299Gly |
| 25 | 14674 | m.14674T\>C | T14674C\-F13 | T14674C\-F13\-P2 | Fam | F | N | N | A | ND | Homo | / | / | / | Healthy |  |
| 26 | 14674 | m.14674T\>C | T14674C\-F14 | T14674C\-F14\-P1 | Fam | F | N | ND | A | ND | Homo | / | / | / | Clinical history unreliable; possible mild muscle weakness | Carrying EARS2 c.358C\>T |
| 27 | 14674 | m.14674T\>C | T14674C\-F14 | T14674C\-F14\-P2 | Fam | ND | N | N | A | ND | / | / | / | / | Healthy |  |
| 28 | 14674 | m.14674T\>C | T14674C\-F14 | T14674C\-F14\-P3 | Fam | ND | N | N | A | ND | / | / | / | / | Healthy |  |
| 29 | 14674 | m.14674T\>C | T14674C\-F14 | T14674C\-F14\-P4 | Fam | ND | N | N | A | ND | / | / | / | / | Healthy |  |
| 30 | 14674 | m.14674T\>C | T14674C\-F14 | T14674C\-F14\-P5 | Fam | ND | N | N | A | ND | / | / | / | / | Healthy |  |
| 31 | 14674 | m.14674T\>C | T14674C\-F14 | T14674C\-F14\-P6 | Fam | F | Y | Y | A | 1 year and 3 months | Homo | / | / | / | Fever, adynamia, and feeding difficulties | Carrying EARS2 c.358C\>T |
| 32 | 14674 | m.14674T\>C | T14674C\-F15 | T14674C\-F15\-II2 | Fam | M | Y | Y | A | 1 month | Homo | / | / | / | Infantile vomiting, feeding difficulty,failure to thrive,pneumonia,sepsis,hypotonia, muscle weakness, dysphagia |  |
| 33 | 14674 | m.14674T\>C | T14674C\-F15 | T14674C\-F15\-II1 | Fam | F | N | N | A | ND | / | / | / | / | Healthy |  |
| 34 | 14674 | m.14674T\>C | T14674C\-F15 | T14674C\-F15\-I2 | Uninf | F | N | N | A | ND | Homo | / | / | / | Healthy |  |
| 35 | 14674 | m.14674T\>C | T14674C\-F16 | T14674C\-F16\-I2 | Uninf | F | N | N | A | ND | Homo | / | / | / | Healthy |  |
| 36 | 14674 | m.14674T\>C | T14674C\-F16 | T14674C\-F16\-II2 | Fam | F | N | N | A | ND | Homo | / | / | / | Healthy |  |
| 37 | 14674 | m.14674T\>C | T14674C\-F16 | T14674C\-F16\-II6 | Fam | M | Y | Y | A | 1 month | Homo | / | / | / | Irritability, lethargy, hypotonia, feeding difficulties, failure to thrive, mild liver involvement |  |
| 38 | 14674 | m.14674T\>C | T14674C\-F16 | T14674C\-F16\-III1 | Fam | M | N | Y | A | 1 month | Homo | / | / | / | Respiratory infection, feeding difficulties, muscular hypotonia, swallowing difficulties, respiratory failure |  |
| 39 | 14674 | m.14674T\>C | T14674C\-F16 | T14674C\-F16\-III2 | Fam | F | N | Y | A | 2 months | Homo | / | / | / | Feeding difficulties, dysphagia, failure to thrive, muscular hypotonia |  |
| 40 | 14674 | m.14674T\>C | T14674C\-F17 | T14674C\-F17\-I2 | Uninf | F | N | N | A | ND | Homo | / | / | / | Healthy |  |
| 41 | 14674 | m.14674T\>C | T14674C\-F17 | T14674C\-F17\-II1 | Fam | F | Y | Y | A | 3 weeks | Homo | / | / | / | Poor feeding, vomiting, failure to thrive, severe muscular hypotonia,swallowing difficulties |  |
| 42 | 14674 | m.14674T\>C | T14674C\-F18 | T14674C\-F18\-III1 | Fam | M | N | N | A | ND | Homo | / | / | / | Healthy |  |
| 43 | 14674 | m.14674T\>C | T14674C\-F18 | T14674C\-F18\-III2 | Fam | F | N | N | A | ND | Homo | / | / | / | Healthy |  |
| 44 | 14674 | m.14674T\>C | T14674C\-F18 | T14674C\-F18\-IV4 | Fam | F | N | N | A | ND | / | / | / | / | Healthy | No molecular testing in child; included because mother has confirmed mutation load and child phenotype is explicitly reported. |
| 45 | 14674 | m.14674T\>C | T14674C\-F18 | T14674C\-F18\-IV5 | Fam | F | N | N | A | ND | / | / | / | / | Healthy | No molecular testing in child; included because mother has confirmed mutation load and child phenotype is explicitly reported. |
| 46 | 14674 | m.14674T\>C | T14674C\-F18 | T14674C\-F18\-IV6 | Fam | F | N | Y | A | 4 | Homo | / | / | / | Gait unsteadiness, poor balance, leg pain, muscle fatigue, feeding difficulties, thin stature, borderline cognition |  |
| 47 | 14674 | m.14674T\>C | T14674C\-F18 | T14674C\-F18\-IV7 | Fam | F | Y | Y | A | Birth | Homo | / | / | / | General hypotonia, areflexia, joint contractures, swallowing difficulty,respiratory infection, motor delay, poor mobility |  |

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