case_images: PMC11226765_01
case_images: pedigree of the studied family (A); darkened square indicates the patient with dopa-responsive dystonia and hatched squares and circles indicate males and females with essential tremor; arrow: index patient; asterisk: genetic testing performed; sanger sequencing confirms the presence of the c.181G>T mutation in GCH1 in heterozygous state (B); partial nucleotide sequence alignment of human GCH1 with orthologs shows evolutionary conservation between species of the nucleotide 181 and the codon 61 (C)
case_images: PAMJ-47-159-g001.jpg
case_images: PMC11226765_01_PAMJ-47-159-g001.jpg
case_images: F1
case_images: Genetic analysis: blood samples were taken from the patient III.2 and family members II.6, II.7 and III.5 (Figure 1A), and genomic DNA was extracted using Wizard  Genomic DNA Purification Kit from Promega. A subsequent targeted segregation analysis by Sanger sequencing validated the presence of the mutation in the patient (Figure 1B) and its absence in the parents, confirming that the mutation has occurred de novo. This de novo nonsense variant affects a highly conserved amino acid (Figure 1C) and is classified as pathogenic according to the ACMG guidelines.