The role of the Clinical Scientist in Genetics in the NHS

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The role of the Clinical Scientist in Genetics in the NHS Powered By Docstoc
					An evaluation of the Cytocell Chromoprobe CLL Panel as a routine diagnostic service in Aberdeen

Julie Turbitt
Grade A Trainee Clinical Scientist

Scottish Genetic Laboratories Consortium 26th November 2008

Chronic Lymphocytic Leukaemia (CLL)


Most frequent leukaemia in the Western world – accounts for 25% of all leukaemias Characterised by the accumulation of mature-appearing neoplastic B-lymphocytes in the blood, bone marrow, and/or lymph nodes





Shows a highly variable clinical course
- some patients survive without therapy for many years with no or minimal symptoms - while others may die within a few months of diagnosis



Prediction of survival based on: - Molecular markers (e.g. ZAP-70, CD38) - IGH mutation analysis - Cytogenetics

Interphase FISH


Chromosomal abnormalities have been identified in CLL patients using a variety of different methods: conventional cytogenetic analysis, interphase FISH, MLPA or array-CGH iFISH is now the preferred method of choice for CLL analysis in the majority of cytogenetic laboratories - difficulties in culturing CLL B-cells for conventional cytogenetic studies Approx. 80% of CLL cases found to be abnormal by iFISH
13q14.3 13q34





Poor: 17p (TP53) deletion, 11q (ATM) deletion Good: Monoallelic 13q deletion



Guidance at moment is for all cases to be monitored for 17p deletion (Eichhorst & Hallek 2007)

Aims and Objectives
This audit aims to determine:


The overall abnormality rate for CLL cases received by the Aberdeen laboratory, from November 2006 until May 2008. The overall success of the Cytocell Panels in the laboratory for routine diagnostic CLL samples by investigating the percentage of CLL panels that are successful on first attempt i.e. those that do not require any additional FISH tests to complete analysis.





To examine the cost of the Cytocell CLL Panel for routine use in the Aberdeen laboratory and to consider if it is the most appropriate commercial test available to best inform referring clinicians.

Methods


For a period of 17 months, samples of peripheral blood, bone marrow, or lymph nodes from 47 patients with a working or established diagnosis of CLL were analysed using the Chromoprobe Multiprobe –System CLL Panel (Cytocell). This panel examines: c-MYB (6q23.3), D12Z1 (chromosome 12), ATM (11q22.3), region D13S319 to D13S25 (13q14.3), TP53 (17p13.1), IGH and CCND1 (t(11;14)), IGH and BCL2 (t(14;18) and IGH (14q32). Location of probes on the Cytocell CLL Panel:



IGH and BCL2 13q14.3

ATM

D12Z1

MYB

IGH and CCND1

TP53

IGH Split

Results
1. ABNORMALITY DETECTION RATE USING THE CYTOCELL CLL PANEL


Panel provided an abnormal karyotype for 57.4% (27/47) of samples tested.
- 13q deletion was the most frequent abnormality detected



Abnormalities associated with prognostic implications were largely detected from patient blood samples (62.5%)

Table 1 – Percentage of sample type showing a prognostic result

CLL (Total No. prognostic samples = 24) Blood Marrow Lymph Node

62.5 %

29.2 %

8.3 %

Table 2 – Summary of abnormal CLL results
NO. OF CASES
1 3 5 1 1 1 1 1 1 1 1 1 1 3 1

ABNORMALITY
del(11q) del(11q), del(13q) del(13q) del(13q) (homozygous), del(13q) (heterozygous) del(13q), 13q del(13q), 13q -, 1F2R2G IGH/BCL2 del(13q), 3x17p del(17p) del(17p), del(6q), -13, +11, +18 del(17p), del(13q), -13, -14 del(17p), -17, +12, -14 del(17p), +12, IGH split del(17p), -17, partial del 3’IGH +12 +12, partial del 3’IGH

PROGNOSIS
Poor Poor Good Good Good ? ? Poor Poor Poor Poor Poor Poor ? Intermediate ? Intermediate

1
1 2

del(6q)
del 3’IGH partial del 3’IGH

Intermediate
? ?

Total cases - 27

Results
2. SUCCESS RATE OF THE CYTOCELL CHROMOPROBE CLL PANEL


Panel had a 1st attempt success rate of 63.8% (30/47 samples)

Table 3 - Percentage of sample type with 1st attempt panel success

Sample type

No. 1st attempt Success 2006

No. 1st attempt Success 2007

No. 1st attempt Success 2008

Average 1st attempt panel success (06-08)

Blood Marrow Lymph Node AVERAGE

3 (Total 4) 0 (Total 1) 0 (Total 0)

8 (Total 11) 15 (Total 18) 0 (Total 2)

2 (Total 4) 2 (Total 7) 0 (Total 0)

66.7 % 65.4 % 0%

60 %

74.2 %

36.4 %

Results
3. FAILURE OF INDIVIDUAL SQUARES/PROBES ON THE CYTOCELL CHROMOPROBE CLL PANEL
Figure 2 – Frequency of individual failed squares on CLL Panel

Frequency of 1st attempt failures

7 6 5 4 3 2 1 0
H/ BC L2 PA NE L ND 1 TP 53 M YB 12 H 13 q1 4. 3 H/ CC CE P AT M IG

IG

FISH PROBES
The ATM probe was accountable for nearly a quarter of 1st attempt panel failures Approx. 9 % of diagnostic cases required a repeat of the entire CLL panel

EN T

IR E

IG

Results
4. CLL SERVICE COST USING THE CYTOCELL CHROMOPROBE PANEL - The total cost of the Cytocell panels (including any additional Vysis FISH probes required) from November 2006 to May 2008 = £6684.10 - Average cost per sample = £142.21 5. COST OF CLL DIAGNOSTIC SERVICE USING ALTERNATIVE COMMERCIAL CLL FISH PROBES
Table 4: Cost summary of Aberdeen CLL routine diagnostic service, using alternative CLL FISH probes Cytocell Multiprobe CLL Panel Cost assuming 1st attempt FISH success Actual cost Potential savings compared to Cytocell Multi-Probe Panel £5734.00 £6684.10 NA Cytocell Liquid CLL Kit Vysis CLL Multi-Colour Probe sets £2737.75 ? Kreatech CLL Dual Colour assays £2726.00 ?

£3290.00 ?

£3394.10

£3946.35

£3958.10

Results
(ii). COST OF ALTERNATIVE FISH PROBE SETS TO INCLUDE ALL PROGNOSTIC INFORMATION PROVIDED BY THE CYTOCELL PANEL, i.e. the inclusion of:

- del(6q) probe and IGH rearrangement information

 

Both the Vysis and Kreatech FISH probe sets do not contain probes to identify deletions of 6q. However, from a total of 47 CLL samples, del(6q) was only observed in 1 patient using the Cytocell panel. Patients with this deletion are classified into the intermediate-risk group. - ? Is it economical or necessary to have kits containing del(6q) FISH probes



Even after the inclusion of a del(6q) probe and IGH rearrangement probes, savings for the CLL routine diagnostic service in Aberdeen are still obtained from the use of alternative CLL FISH probe sets.

Service improvements and Future Plan
This audit revealed that the percentage of Cytocell 1st attempt panel success was low with a number of squares/probes on the panel, in particular ATM, prone to failure.

Laboratory Recommendations:
1. Introduction of alternative FISH CLL kits to the Aberdeen laboratory. 2. Blood samples, as opposed to bone marrow samples should be used for iFISH CLL analysis. 3. Referring clinicians should be consulted regarding what results they require from CLL iFISH analysis - a more economical CLL FISH service could be provided without the inclusion
of probes to detect, e.g. IGH rearrangements or deletion of 6q. - however, the IGH/CCND1 (t(11;14)) probe should still be included, in order to enable atypical B-CLL patients to be distinguished from possible mantle cell lymphoma patients.