Positive clinical, neuropsychological, and metabolic impact of liver transplantation in patients with argininosuccinate lyase deficiency

Liver transplantation (LTx) is increasingly used in Urea Cycle Defects (UCDs) to prevent recurrent hyperammonemia and re-lated neurological irreversible injury. Among UCDs, argininosuccinate lyase deficiency (ASLD) has a more complex phenotypethan other UCDs, with long-term neurocognitive deficits. Therefore, the role of LTx in ASLD is still debated. The impact ofLTx on nine patients with early- onset ASLD was assessed through pre- and post-LTx clinical, neuropsychological, MRI andbiochemical evaluations. After LTx, no episodes of metabolic decompensations were reported. Neuropsychological evaluationsdocumented significant improvement in cognitive/developmental functioning especially in patients transplanted in early child-hood. Improvements were also highlighted in daily living skills and emotional-behavioral problems, with a reduction in atten-tion disturbances and somatic complaints. Movement disorders resolved after LTx in patient transplanted in early childhood.Any patients developed epilepsy with stability of EEG alterations after LTx. A positive effect of LTx on other disease-related out-comes such as growth, diet, medications, hospitalizations, and long-term ASLD-related complications was highlighted. The pri-mary biomarker argininosuccinic acid dramatically reduced in plasma after transplantation with a decreasing trend in CSF atlong-term follow-up. Moreover, health-related quality of life improved after LTx, especially when assessed through MetabQoL, atool designed for intoxication diseases such as ASLD. In conclusion, our study showed a global beneficial impact of LTx in early-onset ASLD patients to avoid episodes of hyperammonemia, and improve neurocognitive outcome, adaptive and behavioraldeficits when performed in early childhood with a dramatic benefit in terms of quality of life.