Figure 1.

Residual enzymatic ASS1 activity correlates with initial biochemical parameters. (A) NH₄ ⁺ _max (µmol/L) subject to residual enzymatic ASS1 activity (%) as determined in the biallelic expression system. Each point represents a single patient (n = 52). Gray line displays estimated regression curve. GAM‐analysis, P < 0.001, R ² = 0.29. (B) Boxplot illustrating NH₄ ⁺ _max (µmol/L) with a residual enzymatic ASS1 activity below or equal to 8.1% (n = 32) and above 8.1% (n = 20). Data are shown as median (black thick line) and mean (triangle), length of the box corresponds to interquartile range (IQR), upper and lower whiskers correspond to max. 1.5 × IQR, each point represents an outlier. Recursive partitioning, P < 0.001. (C) Peak plasma L‐citrulline concentration subject to residual enzymatic ASS1 activity (%). Each point represents a single patient (n = 33). Gray line displays estimated regression curve. GAM‐analysis, P < 0.001, R ² = 0.46. ASS1, argininosuccinate synthetase 1.