β-catenin, which is encoded by the CTNNB1 gene, is essential for the development and functioning of the brain. There are a few documented cases of dystonia related to CTNNB1. Here, we report the case of an 11-year-old Spanish boy referred for movement disorders and gait disturbance. He had motor developmental delay and achieved unassisted walking at 3 years, with a tiptoe gait and valgus foot posture requiring ankle-foot orthoses. Blood tests showed elevated creatine kinase levels (1684 U/L, normal range 62–235). Molecular analysis revealed a deletion in exons 3-9 of the DMD gene, leading to the diagnosis of Becker muscular dystrophy. By age 8, he presents frequent falls due to a dystonic posture of the feet and abnormal movements in the upper and lower limbs. Whole-exome sequencing revealed a novel heterozygous, de novo pathogenic frameshift variant in the CTNNB1 gene (NM_001098209.1):p.Thr297fs/ c.889dupA. Treatment with levodopa/carbidopa (5.3 mg/kg/day) led to a partial clinical improvement, including a decrease in dystonia, measured by the Burke-Fahn-Marsden Dystonia Rating Scale, and choreic movements in all four limbs. We suggest that levodopa contributes to motor improvement in patients with CTNNB1-related dystonia, supporting its inclusion in the differential diagnosis of childhood dopa-responsive dystonia.

Research project: A. Conception, B. Organization, C. Execution;

Statistical Analysis: A. Design, B. Execution, C. Review and Critique;

Manuscript: A. Writing of the first draft, B. Review and Critique.

A.R.B., 1C, 3A

L.M., 1C, 3B

J.A., 1C, 3B

C.B., 1C, 3B

L.C., 1C, 3B

A.N., 1C, 3B

J.D.O.-E., 1A, 1B, 1C, 3B

The legal guardians gave their written consent to the recording of the patient for publication, and the study received ethical approval by the Ethics Committee (ART-03-23). We confirm that we have read the Journal's position on issues involved in ethical publication and affirm that this work is consistent with those guidelines.

Received: 20 March 2024

Accepted: 27 April 2024

Article published online:
03 June 2024

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