(548 days)
The SEEKER System, including the SEEKER Instrument and the SEEKER LSD Reagent Kit-IDUA|GAA|GBA|GLA for use on the SEEKER Instrument, is intended for quantitative measurement of the activity of a-L-iduronidase, a-D-glucosidase, Bglucocerebrosidase and a-D-galactosidase A from newborn dried blood spot specimens as an aid in screening newborns for Mucopolysaccharidosis Type I, Pompe, Gaucher and Fabry diseases. Reduced activity of these enzymes may be indicative of these lysosomal storage diseases. The enzymes measured using the SEEKER LSD Reagent Kit-IDUA|GAA|GBA|GLA and their associated lysosomal storage diseases are listed below.
| Enzyme (abbreviation) | Disease |
|---|---|
| α-L-iduronidase (IDUA) | Mucopolysaccharidosis Type I (MPS I) |
| α-D-glucosidase (GAA) | Pompe |
| β-glucocerebrosidase (GBA) | Gaucher |
| α-D-galactosidase A (GLA) | Fabry |
The SEEKER System employs digital microfluidic technology to measure multiple lysosomal enzymatic activities quantitatively from newborn dried blood spot specimens. The following components are provided:
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- SEEKER Instrument (including USB and power cables), Desktop PC with monitor, keyboard, mouse, and the Spot Logic software.
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- SEEKER LSD Reagent Kit IDUA|GAA|GBA|GLA containing enzyme specific substrate reagents, dried blood spot extraction buffer, reaction stop buffer, 4 levels of calibrators and quality control dried blood spots containing 4 levels of quality control (OC) material. Each Reagent Kit contains sufficient consumables for 1440 tests. The contents of the kit are listed below:
| Component | Contents | Quantity |
|---|---|---|
| Quality control | ||
| dried blood spots | QC-Base Pool (QCBP) | 1x15 spots |
| QC-Low (QCL) | 1x15 spots | |
| QC-Medium (QCM) | 1x15 spots | |
| QC-High (QCH) | 1x15 spots | |
| Enzyme substrates | IDUA | 9x100 µL |
| GAA | 9x100 µL | |
| GBA | 9x100 µL | |
| GLA | 9x100 µL | |
| Calibrators | Calibrant A (CALA) | 9x50 µL |
| Calibrant B (CALB) | 9x50 µL | |
| Calibrant C (CALC) | 9x50 µL | |
| Calibrant D (CALD) | 9x50 µL |
Other components needed to run tests include the following:
| Component | Contents | Quantity |
|---|---|---|
| Other Reagents | Extraction Buffer (EXT) | 9 x 30 mL |
| Filler Fluid | 9 x 10 mL | |
| Cartridge | SEEKER cartridge | 1 x 36 |
The composition of the enzyme reagents and buffers are summarized below:
| Reagent (Description) | Composition |
|---|---|
| IDUA | |
| (α-L-iduronidase substrate) | 2 mM 4-MU-α-L-iduronide sodium salt |
| 3mM D-saccharolactone | |
| 0.04 M acetate buffer, pH 3.5 | |
| 20 mM methyl β-cyclodextrin | |
| 0.01% Tween20 | |
| GAA | |
| (α-D-glucosidase substrate) | 5 mM 4-MU-α-glucopyranoside |
| 12 µM acarbose | |
| 0.04 M acetate buffer, pH 3.8 | |
| 20 mM methyl β-cyclodextrin | |
| 0.01% Tween20 | |
| GBA | |
| (β-glucocerebrosidase substrate) | 16 mM 4-MU-β-glucopyranoside |
| 0.05 M/0.1M citrate phosphate buffer, pH 5.2 | |
| 0.01% Tween20 | |
| 1.5% sodium taurocholate | |
| GLA | |
| (α-D-galactosidase A substrate) | 10 mM 4-MU-α-galactopyranoside |
| 145 μM N-acetyl galactosamine | |
| 0.04 M acetate buffer, pH 4.6 | |
| 20 mM methyl β-cyclodextrin | |
| 0.01% Tween20 | |
| Stop Buffer STB | |
| (reaction stopping buffer) | 0.6 M NaHCO3, pH 11.0 in 0.04% Tween 20 |
| Extraction Buffer EXT | |
| (dried blood spot extraction buffer) | 0.1% Tween 20 in water |
| Filler Fluid | |
| (medium for droplet movement) | 0.1% Triton X-15 in 5cSt silicone oil |
The Seeker Calibrators are supplied as part of the SEEKER LSD Reagent Kit -IDUA|GAA|GBA|GLA. The calibrators consist of 4 levels of aqueous preparation of 4methylumbelliferone sodium salt (4-MU) in 0.6M sodium bicarbonate buffer, pH 11.0 with 0.01% Tween 20. The concentration of 4-MU in each of the 4 calibrators is indicated in the table below:
| Calibrator Level | Concentration of 4-MU |
|---|---|
| Calibrant A (CAL A) | 0.0375 µM |
| Calibrant B (CAL B) | 0.0750 µM |
| Calibrant C (CAL C) | 0.1500 µM |
| Calibrant D (CAL D) | 0.3000 µM |
The quality control dried blood spots include 4 levels of control material: OC Low (QCL), QC Medium (QCM) and QC High (QCH). The composition of the 4 quality control dried blood spot (DBS) is summarized below. QCBP is used to fill empty wells on a cartridge.
| Quality Control Level | Composition |
|---|---|
| QCBP | Heat inactivated human serum, adjusted to ~50% hematocrit |
| using human red blood cells | |
| QCL | 5% cord blood and 95% heat inactivated serum, adjusted to |
| ~50% hematocrit using human red blood cells | |
| QCM | 50% cord blood and 50% heat inactivated serum adjusted to |
| ~50% hematocrit using human red blood cells | |
| QCH | Human umbilical cord blood, adjusted to ~50% hematocrit |
| using human red blood cells |
The enzymatic activity values for the quality control DBS measured by the manufacturer are given on the lot specific quality control certificate included in each assay kit for all levels except QCBP. Each laboratory should establish its own mean and acceptable ranges for the quality control materials.
3. SEEKER Cartridges
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- Finnipipette Novus 8-channel automatic pipette 1-10 uL
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- Finnipipette Novus 1-channel automatic pipette 10-100 uL
The SEEKER System is a device designed for quantitative measurement of the activity of α-L-iduronidase (IDUA), α-D-glucosidase (GAA), β-glucocerebrosidase (GBA), and α-D-galactosidase A (GLA) from newborn dried blood spot specimens. This serves as an aid in screening newborns for Mucopolysaccharidosis Type I (MPS I), Pompe, Gaucher, and Fabry diseases.
Here's an analysis of the acceptance criteria and the study that proves the device meets those criteria:
1. Acceptance Criteria and Reported Device Performance
The acceptance criteria for the SEEKER System are implicitly defined by the analytical and clinical performance standards required for its De Novo classification as a Class II device with special controls. These controls mandate thorough demonstration of performance characteristics, including clinical validity, reference intervals, carry-over, detection limits, and imprecision. The clinical validity is primarily demonstrated by the false positive and false negative rates observed in the pivotal clinical study.
Table: Acceptance Criteria (Implied by Regulatory Requirements) and Reported Device Performance
| Performance Characteristic | Acceptance Criteria (Implied) | Reported Device Performance (Pivotal Phase Study) | Notes |
|---|---|---|---|
| Clinical Validity (False Positive Rate) | Acceptable false positive rates to minimize unnecessary confirmatory testing and emotional burden. | IDUA: 0.035% | |
| GAA: 0.092% | |||
| GBA: 0.047% | |||
| GLA: 0.097% | These rates are considered acceptable, particularly given the benefits of early detection and the fact that newborns with "presumed normal" results after risk assessment were not followed up, potentially leading to an overestimation of the false positive rate. | ||
| Clinical Validity (False Negative Rate) | Acceptable false negative rates to ensure affected newborns are detected and receive timely therapy. | IDUA: 0% | |
| GAA: 0% | |||
| GBA: 0% | |||
| GLA: 0% (Note: 2 newborns that would have been FN at 7.0µmol/L/hr cutoff were TP at 8.0µmol/L/hr cutoff. Labeling specifies known limitations for female Fabry and late-onset Pompe). | The reported 0% false negative rate for IDUA, GAA, and GBA is based on active surveillance and the assumption that early-onset cases would be reported. However, some limitations are disclosed in the labeling, acknowledging potential false negatives due to clinical variability (e.g., late-onset Pompe, female Fabry patients). The adjustment of cutoffs over time also indicates complexities in achieving a perfect 0% FN rate. The note about GLA false negatives suggests that the 0% reported might be dependent on the specific cutoff used at the time. | ||
| Imprecision (Reproducibility) | Reproducibility across different instruments, reagent lots, and days, within acceptable limits. | ||
| (No explicit %CV target stated, but general medical device standards suggest low CVs for reliable quantitative assays). | IDUA: 14.2% - 28.5% CV (depending on concentration) | ||
| GAA: 12.0% - 17.0% CV | |||
| GBA: 15.7% - 38.0% CV | |||
| GLA: 9.4% - 16.3% CV | These CVs are generally considered acceptable for screening assays, especially at lower concentrations where biological variability or technical limitations might be higher. The CLSI EP5-A3 guideline was followed. | ||
| Linearity/Reportable Range | Linear response over the intended measurement range, covering normal and disease-associated values. | IDUA: 2.77 to 50.75 µmol/L/h | |
| GAA: 2.18 to 94.66 µmol/L/h | |||
| GBA: 2.14 to 73.24 µmol/L/h | |||
| GLA: 4.88 to 153.74 µmol/L/h. Max deviation from linearity 88 mg/mL and hematocrit at 66% caused significant negative bias; heparin increased imprecision. | Generally good, but specific interferences identified for IDUA (high protein, high hematocrit, heparin) are crucial for laboratories to consider. These are included in the package insert. | ||
| Carry-over | Demonstrate minimal or no significant impact from carry-over. | Most assays showed minimal bias ( |
§ 862.1488 Lysosomal storage disorder newborn screening test system.
(a)
Identification. A lysosomal storage disorder newborn screening test system is intended to measure lysosomal enzyme levels obtained from dried blood spot specimens on filter paper from newborns as an aid in screening newborns for a lysosomal storage disorder.(b)
Classification. Class II (special controls). The special controls for this device are:(1) Design verification and validation must include information that demonstrates the performance characteristics of the device, including:
(i) Study results that adequately demonstrate the clinical validity of the device, which must include information supporting the link between the analyte being measured and the condition being screened. The clinical validity of the device must be demonstrated in a clinical validation study using either well-characterized prospectively or retrospectively obtained clinical specimens from the intended use population. Testing in the clinical validation study must be performed by operators representative of the types of operators intended to use the test. The study design of the clinical validation study must assess the effects of sample collection and processing steps on test performance. Confirmed positive specimens must have a diagnosis based on confirmatory diagnostic methods or clinically meaningful information regarding the status of the subject must be obtained.
(ii) The reference interval in the normal newborn population for the analyte or analytes measured by the device.
(iii) Study results demonstrating the level of carryover or drift affecting the device performance.
(iv) Study results demonstrating the concentrations of the limit of blank, limit of detection, and limit of quantitation of the device. Sample concentrations below the limit of quantitation must not be reported by the device.
(v) Study results, which must be collected using sample panels from at least three reagent lots and at least three instruments over more than 20 testing days, demonstrating the imprecision of the device. The sample panels must consist of blood spot specimens with a range of analyte concentrations that span the reportable range of the device and must include samples with concentrations in the screen positive range, samples with concentrations at each cutoff, and samples with concentration in the normal range.
(2) The labeling required under § 809.10(b) of this chapter must include:
(i) A warning that indicates that the test is not intended to diagnose lysosomal storage disorders.
(ii) A warning that indicates that test results are intended to be used in conjunction with other clinical and diagnostic findings, consistent with professional standards of practice, including confirmation by alternative methods, and clinical evaluation as appropriate.
(iii) Detailed information on device performance, including the false positive rate and the false negative rate observed in the clinical study.
(iv) Information on device performance in any relevant subgroup (
e.g., age of newborn at time of sample collection, birth weight, sex, gestational age, race, ethnicity) observed in the clinical study.