Monogenic Diabetes Genetic Testing (Blood)

Testing Laboratory

Department

Diagnostic Genetics

Delphic Registration Code (Alpha Code)

DNAT

Test Code (Numeric Code)

7933

Laboratory Handling

Transport

Transport all bloods between >8 degrees C to <24 degrees C within 24-48 hours. If necessary specimens can be refrigerated overnight for transport at the temperatures stated, the following day. For testing of other sample types please contact the laboratory prior to sending.

Registration

Please store specimens at 4 degrees C until processed.

Sample Stability

48 hours at room temperature.

Associated Tests

• DNA Extraction and Storage (Blood)

Synonyms

Maturity-Onset Diabetes of the Young, MODY, Single-gene diabetes

Turnaround Time

12 weeks

Specimen Type

• Whole Blood

Specimen Requirements

Tube/Container Type:

Preferred

• EDTA (Lavender Cap)

Acceptable

• EDTA (Microtainer)

Preferred Sample Volume (ml)

4

Minimum Sample Volume (ml)

0.5

Paediatric Specimen Requirements

Tube/Container Type:

Preferred

• EDTA (Lavender Cap)

Acceptable

• EDTA (Microtainer)

Preferred Sample Volume (ml)

4

Minimum Sample Volume (ml)

0.5

Additional Specimen Information

This test requires viable nucleated cells. Do not centrifuge or freeze the EDTA blood sample.

An aliquot of genomic DNA extracted by another ISO15189 accredited laboratory is also an acceptable specimen type. DNA samples should have a minimum volume of 20 µL and a concentration of at least 20 ng/µL.

If the available DNA does not meet these requirements, please contact the laboratory to discuss sample suitability and any specific testing requirements.

Aliquot Instructions

Sample Type

• Whole Blood

Minimum Volume (ml)

4

Transport to Lab

Ambient (8 - 24 degrees Celsius)

Additional Referral/Aliquot Information

Important Note:

All genetic test requests for MODY require a referral from an endocrinologist. All MODY referrals also require completed Monogenic Diabetes Referral form. See link for MODY referral form under Additional Information below.

The specialty of the referring clinician and the clinical presentation must be provided. Failure to provide the information required may delay testing.

Test Method

Capture-based target enrichment is performed using the Twist Bioscience Enzymatic Fragmentation Library Preparation v1.0 and custom panel. Next-generation sequencing (NGS) is performed on an Illumina MiSeq platform. Variant calls are identified using the Illumina DRAGEN analysis platform v42.4. Variant triage and curation is performed using Illumina Emedgene v38. The coding regions and flanking +/-20bp (encompassing the splice sites) of the following listed genes are sequenced in this test. 100% coverage of bases within these regions is achieved by NGS (to a depth of ≥50x).

The Multiplex Ligation-dependent Probe Amplification (MLPA) kit P241-E1 MODY Mix1 from MRC-Holland is used to detect copy number variations in HNF4A, GCK, HNF1A, and HNF1B.

Uncertainty of Measurement

Please contact the Diagnostic Genetics Pathologist at dgen@adhb.govt.nz to discuss sources of test uncertainty, which include, but are not limited to, measurement uncertainty (MU) and biological variation.

Resources

• Monogenic Diabetes Molecular Genetics Test Form (611 KB)

Contact Information