Table 2.

Results of enzymatic activity on control^aand patient DBS

Enzyme	n	Activity (nmol/ml/h) Average DS Range	CV1	CV2	Pb	Cutoffc
		Arylsulfatase B
Mucopolysaccharidosis type VI (age range: 1.5–17 years)	34	0.0–2.06 M: 1.2 DS:0.67	6.4	11.47	<0.0001	2.7
Controls (<36 days)	21	4.0–31.5 M: 10.1 DS: 5.9
Controls (3 months–59 years)	625	2.9–43.2 M: 9.2 DS: 5.6
		α-Galactosidase A
Fabry disease – men (age range: 10–50.1 years)	23	0.0 –0.3 M: 0.08 DS: 0.09	8.2	10.7	<0.0001	1.15
Fabry disease d - heterozygotes (age range: 28–67 years)	8	0.21–3.34 M: 1.0 DS: 1.0
Controls (<36 days)	80	2.5–21.9 M: 11.3 DS: 5.2
Controls (3 months–88 years)	2337	2.0–21.8 M: 7.4 DS: 3.5
		α-Iduronidase
Mucopolysaccharidosis type I (age range: 8 months–27.7 years)	15	0.0–0.65 M: 0.25 DS: 0.23	5.2	11.3	<0.0001	1.1
Normal control (<36 days)	48	3.0–19.6 M: 9.9 DS: 3.6
Normal controls (3 months–59 years)	1585	1.5–20.1 M: 9.5 DS: 3.8
		β-Galactosidase
Gangliosidosis GM 1 (age range: 7 months–4 years)	10	0.1–2.3 M: 1.4 DS: 0.7	5.3	13.4	<0.01	11.4
Mucopolysaccharidosis type IVB (age: 4 years)	1	2.1
Controls (3 months–88 years)	2354	19–99 M: 47 DS: 16
Controls (<36 days)	166	28–164 M: 71 DS: 26
		β-Glucosidase
Gaucher disease (age range: 4 months–72.8 years)	101	0.39–5.3 M:3.6 DS:1.14	15	14.7	<0.0001	5.6
Controls (6 months–63 years)	715	5.9–16.8 M:9.6 DS: 2.6
		Total Hexosaminidase
Sandoff disease (age: 1 years)	1	42.1	4.1	10.2	<0.0001	111.4
Normal controls (3 months–88 years)	1820	180.8–750.2 M: 396.3 DS:120.8
Controls (<36 days)	114	284.3–884.1 M: 527.2 DS: 130.2
Overexpression of total Hexosaminidase activity**	32	856.4–4882.8 M: 1538.3 DS: 913.1
		Iduronate Sulfatase
Mucopolysaccharidosis type II (age range: 1.1–35 years)	31	0.0 –1.86 M: 0.86 DS: 0.43	8.0	11.2	<0.0001	6.3
Controls (<36 days)	11	19.1–44.2 M:32.8 DS: 9.3
Controls (3 months–59 years)	210	10.7–45.2 M: 24.8 DS: 7.3
		Chitotriosidase
Patients affected by Gaucher disease and elevated chitotriosidase	86	120.9–3479.8 M:1108.9 DS: 789.9	9.4	12.4	<0.0001	96.7
Patients affected by Gaucher disease without elevated chitotriosidase*	15	0.0–80.8 M: 41.3 DS: 34.8
Patients affected by other lysosomal disorders***	74	20.3 – 1649.6 M: 229.1 DS:231.5
Controls (3 months–78 years)	518	2.3 –96.1 M:36.3 DS:23.2

^aAccording to the Shapiro-Wilk test, all control groups analyzed failed to show a normal distribution (Sig. <0.05 with 95% confidence)

^bCited values correspond to the results of the non-parametric Mann-Whitney test comparing activity values of individuals affected by enzyme deficiency and healthy controls

^cObtained through ROC (Receiver Operating Characteristics) analysis, based on a comparison between results for patients and control individuals (99 % confidence, 100 % sensitivity, and 100 % specificity). Both sensitivity and specificity values refer to the certainty offered by each cutoff for the enzyme analyzed. The ROC analysis was made with the complete dataset

^dResults correspond to obligated heterozygotes (mothers of Fabry patients) who at the time of this writing are still not under clinical follow-up

*All referred patients with clinical findings suggesting Gaucher disease were evaluated for chitotriosidase. Eight cases showed increased Chitotriosidase activities (range: 105–1650 nmol/ml/h) with normal β–glucosidase activity in leukocyte samples; subsequent studies indicated Niemmann Pick disease (data not shown)

**The values shown do not establish a cutoff for the overexpression. Some patients with a confirmed diagnosis of LSD (n = 32) showed increases of 1.5 to 6.5 times above the reference value. (range: 180.8–750.2 nmol/ml/h). This study is in progress

***Patients with other LSDs and increased chitotriosidase: Gangliosidosis GM1 (n = 3), Fabry disease (n = 3), MPS I (n=2), MPS II (n = 1), MPS VI (n=1), MPS VII (n = 1)

CV₁: Intra assay variability coefficient. (%)

CV²: Inter assay variability coeffcient. (%) (n = 30)