A production system to generate reference genetic profiles from buccal swab cells on FTA^® cards

Article Outline

• Abstract
• 1. Introduction
• 2. Materials and methods
  • 2.1. Application protocol
  • 2.2. Software
• 3. Discussion
• Conflict of interest statement
• Acknowledgement
• Copyright

Abstract 

To generate the large quantity of genetic profiles that continuously feeds the French Reference Sample Database (F.N.A.E.G.), a secure and robust process is required. A complete automated production chain has been developed by Hamilton Robotics and the French Police Scientifique in Lyon to produce genetic profiles from buccal swab cells on FTA^® cards. The activities have been divided between Pre- and Post-PCR. The samples on FTA^® cards are punched directly into PCR plates. The plates are then transferred onto the Hamilton Microlab^® STAR liquid handling instruments. Air displacement pipetting coupled with Hamilton's CO-RE Technology allows a highly secure and contamination free pipetting for FTA^® wash and STR^® Identifiler^® PCR reaction set-up. Plates are sealed and transferred to the Post-PCR system for pooling into 384 format and denaturation. Throughout the process steps a complete sample tracking is performed and sample information is transferred to the LIMS system. This poster describes in detail this production system with an actual throughput of 40,000samples/month, which is in production since 2006.

Keywords: Automation, Forensics, Reference, Database, Genotyping, Robotics, FTA, Casework, High-throughput

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1. Introduction 

A complete automated production chain has been developed by Hamilton Robotics and the French Police Scientifique in Lyon to produce genetic profiles from buccal swab cells on FTA^® cards. The activities have been divided between Pre- and Post-PCR. Throughout the process steps a complete sample tracking is performed and sample information is transferred to the LIMS system. This article describes in detail this production system with an actual throughput of 40,000samples/month, which is in production since 2006.

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2. Materials and methods 

The complete system consists of four plateforms based on the Microlab Star Plus instruments. Samples are processed on two identical Pre-PCR systems and two identical Post-PCR systems (Fig. 1).

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• Fig. 1. 

  Pre- and Post-PCR system 3D views.

2.1. Application protocol 

The protocol details are as follows (also see Fig. 2):

(e)The plates are transferred to a Hamilton Temperature controlled carrier (4°C). The STR^® Identifiler^® mastermix (Applied Biosystems Inc., Foster City, USA) is distributed by the 96-Probe Head (12.5μl) into the plates containing the dried punched samples.

(g)Automatic sealing is performed (Roboseal, HJ-Bioanalytik Gmbh, Mönchen-gladbach, Germany). Plates are then stored back at 4°C and the user can remove plates and start a new batch.

(i)After thermocycling, a set of 4×96-Well PCR plates containing the amplified samples are loaded onto the Hamilton MICROLAB^® StarPlus Post-PCR system and automatically centrifuged (SIAS IXION centrifuge).

(k)The Formamide+LIZ (9μl) is distributed by the single channels in each well of an empty 384-Well PCR plate (Hard-Shell^®, Bio-Rad Laboratories Inc.). Then 1μl of all samples is transferred from each of the four 96-Well PCR plates into the 384-Well PCR plate.

(m)After centrifugation this plate is consecutively transferred to 95°C and 4°C for sample denaturation.

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• Fig. 2. 

  Automated protocol steps.

The user can remove the processed plates and start a new run.

2.2. Software 

All methods were programmed using the new Hamilton Venus One Software package. The dynamic scheduler enables the user to add or remove tasks at all times during runtime (Fig. 3). The advanced features of the Venus One software allow sample tracking throughout the process. To track sample ID at all steps of the process, files are imported to and from the LIMS system.

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• Fig. 3. 

  Scheduling of a day's work with Venus One Dynamic Sched.

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3. Discussion 

Since its installation in September 2006 over 300,000 genotypes have been processed in duplicate on the Pre- and Post-PCR systems and entered in the F.N.A.E.G. (French National Fingerprint Database). The initial system's throughput was set to 20,000samples/month. In December 2008 this throughput was increased to 40,000samples/month without any major hardware modifications.

The scheduling of the methods was modified to optimise batch processing and an additional heating position was added to the Pre-PCR chains to allow parallel processing of two plates. The automated punchers were also uncoupled to improve task scheduling. In Post-PCR, no hardware was modified. The method programming was optimised and the PCR reaction is now performed off line for more flexibility.

In addition, the new Venus One software was installed. The creation of Genetic databases requires a very high number of samples to be processed and therefore a highly reliable and robust production tool is needed. Hamilton Robotics quality products and engineering have proven to be great tools for automation of human genetic identification both for reference as shown here and for casework samples.

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Conflict of interest statement 

None.

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Acknowledgement 

Acknowlegments to the U.A.G. team I.N.P.S. for their great contribution to this work.