Table 3.

Binary trait heritability (h ²)

Trait	Number of cases	h 2	SE	P value	Kullback‐Leibler R 2
Psychiatric involvement	214	0.55	0.19	0.0016	0.01 **
Cerebellar ataxia	213	0.46	0.37	0.0957	0.19
Migraine	214	0.77	0.33	0.0104	0.05 *
Cognition	205	0.46	0.91	0.1023	0.04
Dysphonia–dysarthria	213	0.13	0.53	0.4019	0.15
Encephalopathy	214	0.64	0.36	0.0408	0.10
Stroke‐like episodes	214	0.51	0.49	0.1423	0.12
Visual acuity	210	0.26	0.26	0.2130	0.04
Ptosis	213	0.15	0.39	0.3510	0.08*
CPEO	213	0.47	0.52	0.2102	0.06
Hearing impairment	214	0.52	0.38	0.0886	0.23*
Diabetes	214	0.37	0.35	0.1462	0.22
Cardiovascular involvement	193	0.08	0.36	0.4066	0.13

Converting NMDAS scores to a binary trait leads to a loss of information and, as a result, it was not possible to calculate heritabilities for neuropathy, seizures, gastrointestinal disturbance, or myopathy. Kullback‐Leibler R ² represents the information gained by including heteroplasmy level and age (*and sex, where P < 0.1) in the model. **Psychiatric involvement was analyzed as a quasi‐quantitative trait to avoid numerical problems in SOLAR, and therefore, this figure represents the proportion of variance due to covariates. Bold indicates significant heritabilities (P < 0.05).