In:
Movement Disorders, Wiley, Vol. 34, No. 10 ( 2019-10), p. 1516-1527
Abstract:
Childhood‐onset dystonia is often genetically determined. Recently, KMT2B variants have been recognized as an important cause of childhood‐onset dystonia. Objective To define the frequency of KMT2B mutations in a cohort of dystonic patients aged 〈 18 years at onset, the associated clinical and radiological phenotype, and the natural history of disease. Methods Whole‐exome sequencing or customized gene panels were used to screen a cohort of 65 patients who had previously tested negative for all other known dystonia‐associated genes. Results We identified 14 patients (21.5%) carrying KMT2B variants, of which 1 was classified as a variant of unknown significance. We also identified 2 additional patients carrying pathogenic mutations in GNAO1 and ATM . Overall, we established a definitive genetic diagnosis in 23% of cases. We observed a spectrum of clinical manifestations in KMT2B variant carriers, ranging from generalized dystonia to short stature or intellectual disability alone, even within the same family. In 78.5% of cases, dystonia involved the lower limbs at onset, with later caudocranial generalization. Eight patients underwent pallidal DBS with a median decrease of Burke‐Fahn‐Marsden Dystonia Rating Scale‐Motor score of 38.5% in the long term. We also report on 4 asymptomatic carriers, suggesting that some KMT2B mutations may be associated with incomplete disease penetrance. Conclusions KMT2B mutations are frequent in childhood‐onset dystonia and cause a complex neurodevelopmental syndrome, often featuring growth retardation and intellectual disability as additional phenotypic features. A dramatic and long‐lasting response to DBS is characteristic of DYT‐ KMT2B dystonia. © 2019 International Parkinson and Movement Disorder Society
Type of Medium:
Online Resource
ISSN:
0885-3185
,
1531-8257
Language:
English
Publisher:
Wiley
Publication Date:
2019
detail.hit.zdb_id:
2041249-6