On this page, you will find information about a genetic change that was identified in UDN participants. We are trying to find others with the same or similar condition.

Sharing information on this website is not a requirement of UDN participation. Only descriptions about participants who give explicit consent will appear here.

Date of Report

Aug 22, 2017

Full Name

Mitochondrially encoded tRNA leucine 2

Mitochondrial DNA


The MT-TL2 gene encodes the mitochondrial tRNA for leucine.

Database Links

GeneCards: GCMTP012268

NCBI Gene: 4568

OMIM: 590055

Clinical Significance

A change in the MT-TL2 gene was identified in two UDN participants. Research is underway to see if this change is causing symptoms in these patients.

The participants, two male siblings ages 4 and 5 with developmental delay and abnormal MRI findings (T2 hyperintensity of caudate nuclei and putamen bilaterally), were found to carry the following genetic change in the MT-TL2 gene: m.12297T>C.

Gene MT-TL2
Inheritance Pattern Mitochondrial, homoplasmic
Transcript NC_012920.1
DNA Change m.12297T>C
Protein Change

At 6 months, the older brother was not sitting or rolling and was found to have low muscle tone (hypotonia). Over time, his hypotonia has become more noticeable and currently he is unable to stand or walk. He has also developed involuntary muscle contractions (dystonia) and problems with coordination (ataxia). The patient does not communicate verbally, but uses an assistive communication device. He is very social and engaged.

His younger brother is similarly affected, but has not developed dystonia. In addition to the symptoms above, the patients also have abnormal MRI findings (T2 hyperintensity of caudate nuclei and putamen bilaterally).

Some of their other features include:

  • Global developmental delay
  • Dystonia
  • Abnormal crease on the palm of the hand (bridged palmar crease)
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