Patients with unexplained CLD had a lower median serum ALT activity (30 U/L [IQR 21–51] vs. 41 [IQR 24–58]; p = 0.032) and values above the upper reference range (URR) were observed in proportionately fewer patients than amongst those in whom the aetiology was known (31.3% vs. 50.7%; p = 0.016). This evidence concerns the gene GPT and congenital secretory chloride diarrhea 1.