Table 1.

Characteristics of patients identified with APRT deficiency and tests used for diagnosis (alone or in combination)

No. of families43
No. of patients53
    <16 years (n [%])20 (37.7)
    >16 years (n [%])33 (62.3)
Male gender (n [%])34 (64.1)
Age at diagnosis (years; median [IQR])36.3 (6.4 to 50.5)
Tests leading to diagnosis (n [%])
    stone analysis31 (58.5)
    crystalluria15 (28.3)
    renal biopsy6 (11.3)
        native kidney2 (3.8)
        transplant3 (5.7)
        both1 (1.9)
    APRT activity (overall)41 (77.4)
    APRT activity in asymptomatic2 (3.8)
  • For some patients, several diagnostic tests were simultaneously performed (e.g., crystalluria and stone analysis). For five patients, diagnosis was made directly by APRT activity measurement in the setting of familial screening. IQR, interquartile ratio.