Successful newborn screening for Gaucher disease using fluorometric assay in China

Abstract

Gaucher disease (GD) is an inherited metabolic disorder that involves accumulation of glycolipid glucocerebroside in monocyte–macrophage cells, which can result in multiple organ damage. Enzyme replacement and substrate reduction therapies have improved the potential for early diagnosis and treatment. Determining the true incidence of this rare disease is critical for relevant policy establishment. Newborn screening allows for early diagnosis and an comparatively accurate incidence of GD. A fluorometric method to detect acid β-glucocerebrosidase (GBA) activity on a dried blood spot punch was developed. Validity and feasibility of the fluorometric method was demonstrated by examining 116 healthy controls, 19 confirmed GD patients and 19 obligate carriers. GBA activity was measured on dried blood spots of 80 855 newborns. Samples from positively screened newborns were reanalyzed by a leukocyte GBA activity test and GBA gene analysis. Plasma glucosylsphingosine level was determined as a biomarker of the pathophysiology of GD. GD patients were distinguished from healthy controls and obligate carriers using the fluorometric method. Mean GBA activity in newborn screening specimens was 145.69±44.76 μmol l−1 h−1 (n=80 844). Three children had low GBA activity, of which one child had low GBA activity on the second dried blood spot specimen. Leukocyte, genetic and biomarker analysis confirmed the diagnosis and indicated that this child was in the early stages of GD. In conclusion, the incidence of GD in Shanghai of China is approximately 1 in 80 855. Screening for GD by fluorometric analysis of GBA activity is an efficient and feasible technology in newborns.

Value of Glucosylsphingosine (Lyso-Gb1) as a Biomarker in Gaucher Disease: A Systematic Literature Review

“…Further, Polo et al reported a significant elevation of lyso-Gb1 in neonatal dried blood spots using a newly developed and validated assay [ 120 ]. These findings support the value of measuring lyso-Gb1 in dried blood spots as a means to conduct high-throughput newborn screening, first conducted by Kang et al in China [ 3 ]. Although few countries have newborn screening programs that include GD, high rates of false positives have been reported on the measurement of enzyme activity on dried blood spots [ 121 , 122 ], and second-tier analyses are being introduced.…”

“…Using the NICE STA method, risk of bias in the sole randomized controlled trial was deemed low, although bias regarding the allocation concealment process and between-group baseline similarities was unclear ( Table S1 ) [ 36 ]. Thirty non-randomized clinical trials and observational studies with full-study reporting were assessed using the Newcastle–Ottawa scoring tool [ 3 , 26 , 33 , 37 , 38 , 39 , 40 , 41 , 42 , 43 , 44 , 45 , 46 , 47 , 48 , 49 , 50 , 51 , 52 , 53 , 54 , 55 , 56 , 57 , 58 , 59 , 60 , 61 , 62 , 63 ], of which 19 were deemed to have a high risk of bias (score 0–3; Table S2 ). Thirty-two animal studies were assessed using the SYRCLE risk of bias tool [ 45 , 53 , 58 , 64 , 65 , 66 , 67 , 68 , 69 , 70 , 71 , 72 , 73 , 74 , 75 , 76 , 77 , 78 , …”

“…Eleven studies provided information relevant to the diagnosis of GD [ 3 , 26 , 33 , 38 , 40 , 41 , 44 , 46 , 47 , 49 , 50 ]. Normally, lyso-Gb1 is undetectable or found at trace levels in plasma (i.e., <4.9 ng/mL (10.61 nmol/L)) and tissue [ 39 , 114 ].…”

“…Normally, lyso-Gb1 is undetectable or found at trace levels in plasma (i.e., <4.9 ng/mL (10.61 nmol/L)) and tissue [ 39 , 114 ]. Data from five prospective observational studies indicated consistently that lyso-Gb1 in plasma and red blood cell (RBC) membranes were higher in untreated patients with GD than in control subjects ( Table 4 ) [ 3 , 26 , 40 , 44 , 46 ]. In addition, findings from an open-label pilot clinical trial showed that lyso-Gb1 in cerebrospinal fluid were below the lower limit of quantification (10.0 pg/mL (21.66 pmol/mL)) in all control subjects but were elevated in patients with neuronopathic GD [ 49 ].…”

“…Gaucher disease (GD) is an autosomal recessive disease of glycosphingolipid metabolism caused by a functional deficiency of the lysosomal enzyme β-glucocerebrosidase (glucosylceramidase (GBA); EC 3.2.1.45), resulting from variants in the GBA1 gene [ 1 , 2 ]. GD is one of the more common lysosomal storage disorders, occurring with an incidence of approximately 1 in 50,000 to 100,000 live births [ 3 , 4 ], although genetic studies indicate a homozygote frequency of ∼1:850 in the Ashkenazi Jewish population [ 5 ].…”