The first report of primary hypotonia with abnormal electromyogram and CBS mutation in a Chinese child

Figures

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  Fig. 1. Slit-lamp examination showed a superonasal displacement of the crystalline lens. The white arrow indicates the edge of the dislocated lens

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  Fig. 2. Brain MRI showed no abnormality

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  Fig. 3. Pedigree of the family. Black symbols represent affected persons and symbols with a dot are carriers (The mother was a presumed carrier). The proband is indicated by an arrow.NT: not tested

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  Fig. 4. Sanger sequencing of the patient and his father. The mutation c.767G > T (p.G256V) was from the father

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  Fig. 5. Orthologous protein sequence alignment of CBS from multiple species. Mutated residues R317 and G256 are boxed

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  Fig. 6. Demonstration of CBS protein structure under changes. The ligands pyridoxal 5’-phosphate and protoporphyrin IX in the CBS protein were marked in red and purple, respectively (a). To better visualize the key residues at 256 and 317 positions, the model was laterally rotated and the G256 and R317 were marked in the mode of lines and sticks (b, c). The mutant P35520_G256V was made by replacing 256Gly with Val, which turns the residue to pyridoxal 5’-phosphate and occupied more space (d). The mutant P35520_R317G was made by replacing 317Arg with Gly, and thus a sharply released internal space could be seen on the relatively out layer of the model (e)