(96 days)
The eSensor® CF Genotyping Test is an in vitro diagnostic device used to simultaneously detect and identify a panel of mutations and variants in the cystic fibrosis transmembrane conductance regulator (CFTR) gene in genomic DNA samples isolated from human peripheral whole blood specimens. The panel includes mutations and variants recommended by the 2004 American College of Medical Genetics (ACMG). The eSensor® CF Genotyping Test is a qualitative genotyping test that provides information intended to be used for cystic fibrosis carrier screening as recommended by ACMG and the 2005 American College of Obstetricians and Gynecologists (ACOG) for adults of reproductive age, as an aid in newborn screening for cystic fibrosis, and in confirmatory diagnostic testing for cystic fibrosis in newborns and children. The test is not indicated for use in fetal diagnostic or pre-implantation testing. This test is also not indicated for stand-alone diagnostic purposes and results should be used in conjunction with other available laboratory and clinical information.
The eSensor® CF Genotyping Test is intended for use on the eSensor® XT-8 System.
The eSensor® CF Genotyping Test on the eSensor® XT-8 System is an in vitro diagnostic device for performing hybridization and genotyping of multiple mutations and/or polymorphisms in an amplified DNA sample. A single-use, disposable test cartridge is used to perform hybridization and genotyping. The cartridge contains an EEPROM chip which transmits the cartridge lot number, expiration date and protocol identity to the XT-8 instrument.
The analysis process for each sample consists of three steps: 1) Genomic DNA isolated from whole blood obtained using EDTA as anti-coagulant is combined with PCR Mix and Taq polymerase enzyme and is subjected to amplification of target sequences by PCR using a thermal cycler. 2) Amplified DNA is treated with exomuclease enzyme to generate single-stranded target DNA. 3) Single-stranded, amplified target DNA is mixed with hybridization and genotyping reagents and transferred to an eSensor® CF Genotyping Tet cartinge, and the cartridge is inserted in the eSensor® XT-8 Instrument controls the circulation of the sample inside the cartridge to allow hybridization at a controlled temperature and then detects and genotypes the sample by voltammetry.
Genotyping of the test panel polymorphisms is achieved by a sandwich assay principle: 1) Each pair of electrodes contains a different synthetic oligonucleotide capture probe which is complementary to one of the target DNA fragments. 2) The hybridization reagents contain pairs of ferrocenc-labeled synthetic oligonucleotide signal probes; one member of each pair is complementary to the major allele sequence of the target polymorphism, while the second member of the pair is complementary to the minor allele sequence. Each member of the probe pair has a ferrocene label with a different oxidation potential for each allele. 3) Single-stranded, amplificd target DNA hybridizes to its specific capture probe, and in turn hybridizes to the allele-specific, ferrocenc-labeled signal probe. 4) Each electrode of the array is analyzed by voltammetry; the target polymorphism is determined by the location of the electrode containing the capture probe, and the genotype is identified by the ratio of signals from the allclespecific ferrocene labels. The array also includes positive and negative confirm the hybridization reaction and detect non-specific signals.
Upon completion of the test, the EEPROM chip on the cartridge contains information that prevents its re-use with a new sample. The eSensor® XT-8 instrument analyzes the results and provides a report of the test results.
The eSensor® CF Genotyping Test on the XT-8 System is an in vitro diagnostic device intended for genotyping multiple mutations or polymorphisms in an amplified DNA sample utilizing electrochemical detection technology.
Here's an analysis of the acceptance criteria and the study that proves the device meets them:
1. Table of Acceptance Criteria and Reported Device Performance
The acceptance criteria are implied through the successful demonstration of 100% agreement with DNA sequencing after repeat testing for initial no-calls across various studies. The primary performance metric is the agreement with the gold standard (DNA sequencing).
| Acceptance Criteria (Implied) | Reported Device Performance |
|---|---|
| Overall Agreement | 100% (after repeat testing for initial no-calls) for all studies |
| First-pass Correct Calls | Varies by study/site, generally high (e.g., 96.9% to 100%) |
| First-pass No-calls | Present in some initial runs, resolved to 100% correct after repeats |
| First-pass Miscalls | 0% (across all studies at first-pass and final) |
2. Sample Sizes and Data Provenance
- Test Set Sample Sizes:
- Reproducibility Study: 22 gDNA samples containing positive calls for all ACOG/ACMG panel mutations and the 5/7/9T polymorphism. Each sample was run in duplicate, generating 1320 total replicates across multiple sites and operators.
- Lot-to-Lot Reproducibility: 21 genomic DNA samples covering all possible genotypes.
- Genomic DNA Extraction Reproducibility: 20 whole blood samples of different genotypes.
- Method Comparison: 112 gDNA samples extracted from whole blood.
- Data Provenance: The document does not explicitly state the country of origin for the data or whether it was retrospective or prospective. Given the nature of a 510(k) submission for a diagnostic test, it is highly likely that samples were collected prospectively or obtained from biobanks with appropriate ethical approvals, and the studies were conducted in a controlled, prospective manner to validate device performance. The reproducibility study involved an "Internal Site" and "External Sites," suggesting multi-center data collection, likely within the USA where the manufacturer is located.
3. Number of Experts and Qualifications for Ground Truth Establishment
The document does not explicitly state the number of experts or their qualifications for establishing the ground truth. However, the ground truth was established using DNA sequencing, which is a widely accepted gold standard in genetic testing. The interpretation of DNA sequencing results for CFTR mutations is a specialized task typically performed by molecular geneticists or clinical laboratory directors with expertise in sequencing analysis.
4. Adjudication Method for the Test Set
The document does not describe a formal adjudication method (e.g., 2+1, 3+1). Instead, discrepancies (initial "no-calls") in the device's output were resolved by re-running the tests, leading to "Final Correct Calls." Miscalls were not observed.
5. Multi-Reader Multi-Case (MRMC) Comparative Effectiveness Study
No multi-reader multi-case (MRMC) comparative effectiveness study was done. This device is an automated genotyping test, not an imaging device that would typically involve human readers for interpretation. The comparison is between the automated device's output and the established DNA sequencing results, and not aimed at quantifying human reader improvement with AI assistance.
6. Standalone Performance
Yes, standalone performance (algorithm only without human-in-the-loop) was performed. The eSensor® CF Genotyping Test is an automated system that provides results via a software program on the eSensor® XT-8 instrument. The performance data presented (reproducibility, method comparison, limit of detection, interfering substances) all reflect the standalone analytical performance of the device without explicit human intervention in the result interpretation process (beyond standard laboratory procedures for running the test and reviewing the final report).
7. Type of Ground Truth Used
The type of ground truth used was DNA sequencing. This is explicitly stated as the reference method for comparison throughout the performance characteristics section (e.g., "All samples gave 100% correct calls when compared with DNA sequencing," and "All samples gave 100% agreement with DNA sequencing").
8. Sample Size for the Training Set
The document does not specify a separate training set size for the device's development or algorithm. This is common for predicate-based 510(k) submissions of in vitro diagnostic devices where the focus is on analytical and clinical validation of the final product, rather than the development process of a machine learning algorithm that typically requires a distinct training phase. The device uses established electrochemical detection technology and a predefined panel of mutations, not a learning algorithm that would necessitate a large training dataset as seen in modern AI/ML submissions.
9. How Ground Truth for the Training Set Was Established
As no separate training set is explicitly mentioned or seems applicable in the context of this device's technology, the method for establishing ground truth for a training set is not provided. The development of the device likely relied on established scientific knowledge of CFTR mutations and electrochemical detection principles, rather than an iterative machine learning training process. The validation studies (using DNA sequencing as ground truth) confirm the performance of the final device.
§ 866.5900 Cystic fibrosis transmembrane conductance regulator (CFTR) gene mutation detection system.
(a)
Identification. The CFTR gene mutation detection system is a device used to simultaneously detect and identify a panel of mutations and variants in the CFTR gene. It is intended as an aid in confirmatory diagnostic testing of individuals with suspected cystic fibrosis (CF), carrier identification, and newborn screening. This device is not intended for stand-alone diagnostic purposes, prenatal diagnostic, pre-implantation, or population screening.(b)
Classification. Class II (special controls). The special control is FDA's guidance document entitled “Class II Special Controls Guidance Document: CFTR Gene Mutation Detection System.” See § 866.1(e) for the availability of this guidance document.