Nov 21, 2016
Potassium voltage-gated channel subfamily D member 3
The KCND3 gene codes for an alpha subunit of a voltage-gated potassium channel (Lee et al., 2012).
Changes in the KCND3 gene have been found in individuals with Brugada syndrome 9 and spinocerebellar ataxia 19.
A change in the KCND3 gene was also identified in a UDN participant. Research is underway to see if this change is causing symptoms in this patient.
The participant, a 49-year-old female with muscle weakness, balance problems, clumsiness, muscle twitching (fasiculations) and cramps, abnormal heart rhythm (second-degree AV block), episodes of high potassium (hyperkalemia), restrictive lung disease, double vision (diplopia), and seizures was found to carry the following genetic change in the KCND3 gene: c.1348C>T/ p.L450F.
The patient has double vision (diplopia on lateral gaze) with weakness (opthalmoplegia) and started having seizures (left temporal lobe focus). These seizures are now controlled with carbamazepine treatment and a pacemaker.
The patient also has an abnormal heart rhythm (second-degree AV block) and had a pacemaker implanted at age 48. Based on recent imaging findings, she has probable early heart disease (cardiomyopathy).
She has been diagnosed with a potassium channel disease (channelopathy) with impaired renal excretion, and has had several episodes of extreme high potassium (hyperkalemia) with dramatic ECG changes, respiratory failure, and very low serum phosphate.
The patient also has stage 3 thyroid cancer (multifocal papillary).
Some of her other features include:
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