case_images: PMC8356262_01
case_images: A: Cranial magnetic resonance imaging shows no abnormality in (a) T1 and (b) T2 axial sequences.
  B: Transverse dopamine transporter image with
  123I-beta-CIT (2beta-carbomethoxy-3beta-(4-iodophenyl)tropane) single-photon emission computed tomography demonstrates normal binding of radioligand in both caudate nuclei and putamina.
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case_images: PMC8356262_01_f1000research-10-54602-g0000.jpg
case_images: f1
case_images: Cranial magnetic resonance imaging and dopamine transporter (DAT) imaging with 123I-beta-CIT (2beta-carbomethoxy-3beta-(4-iodophenyl) tropane) single-photon emission computed tomography were normal ( Figure 1).
case_images: A: Sanger sequencing chromatogram which shows a novel heterozygous mutation c. 542T>G (p. Val181Gly) in the first amino acid of exon 5 in the GCH1 gene (
  black arrow).
  B: Amino acid sequence alignment of the GCH1. Note that the first Val in exon 5 (highlighted in
  red) is highly conserved across species. Residues involved in catalysis are highlighted with
  black triangles
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case_images: PMC8356262_01_f1000research-10-54602-g0001.jpg
case_images: f2
case_images: Val181Gly) in the first amino acid of exon 5 in GCH1 gene ( Figure 2A). The first Val in the 5th exon was located in the enzymatic core of GCH1 at the C-terminus , and is highly conserved across species ( Figure 2B).