"In HLCS deficiency; has normal or low KM values for biotin (non-KM mutant); growth of patients' fibroblasts is compromised compared with normal fibroblasts; patients cells are not sensitive to biotin-depletion from the media; growth rates cannot be restored by re-administration of biotin; enzyme activity is severely compromised and cannot be increased by additional biotin; turn-over rate for the mutant protein is double that of wild-type enzyme."xsd:string