PB1301 - Immunofluorescent test detection of MYH9 gene associated mutation in Malaysia: A simple approach for detection of platelet disorders when molecular testing is not available.

Tuesday, June 25, 2024

13:45 – 14:45 ICT

Room: Exhibition Hall

Presenting Author(s)

Nurasyikin Yusof, FRCPA

Associate Profesor
Universiti Kebangsaan Malaysia Medical Centre
Cheras, Kuala Lumpur, Malaysia

Co-Author(s)

HR

Hari Priya Raghvan

Haematologist
UKM Medical Centre
Kuala Lumpur, Kuala Lumpur, Malaysia
DA

Dr Suria Abdul Aziz

Haematologist
UKM Medical Centre
cheras, Kuala Lumpur, Malaysia
NT

Nor Rafeah Tumian

Clinical Haematologist, Clinical Haematology Unit, Department of Medicine, UKM Medical Centre
National University of Malaysia/UKM
CHERAS, Kuala Lumpur, Malaysia
CL

CKhai Loh

Pediatrician
UKM Medical Centre
cheras, Kuala Lumpur, Malaysia
Marie-Christine Morel-Kopp, PhD

Senior Scientist
Northern Blood Research Centre, Kolling Institute of Medical Research, The University of Sydney, Sydney, Australia
St Leonards, New South Wales, Australia
Christopher M. Ward, BMedSc MBChB PhD FRACP FRCPA

Clinical Director, Division of Cancer Haematology and Palliative Care
Northern Sydney Local Health District/University of Sydney
St Leonards, New South Wales, Australia

Background: Molecular testing for platelet disorder is not available in Malaysia. We explore the immunofluorescent test detecting Myosin heavy chain 9 (MYH9)-related platelet disorders (MYH9-RD) gene mutation that encodes the non-muscle myosin heavy chain IIA (NMMHC-IIA), a cytoskeletal contractile protein. Pathogenic MYH9 variants cause NMMHC-IIA aggregation in neutrophils. Blood smear immunofluorescence detecting the abnormal protein aggregates is a sensitive and specific screening tool used to validate variant pathogenicity.

Aims: This study was conducted to evaluate the potential of immunofluorescent test screening for suspected MYH9-RD in Malaysia.

Methods: A prospective study was conducted on 34 patients with chronic and refractory immune thrombocytopenia using immunofluorescent testing. Presence of abnormal aggregates of NMMHC-IIA indicates positive immunofluorescent test.

Results: Out of 34 patients, 3 (8.8%) patients had a positive immunofluorescent test, 2 with Type II inclusions and 1 with Type III inclusions. They all had moderate thrombocytopenia with unrecordable mean platelet volume (MPV) indicating platelet anisocytosis and presence of large platelets. One patient showed inclusion like bodies in the full blood picture. Two of the cases had family history of ITP/easy bruising. Full physical examination showed no other clinical manifestation.

Conclusion(s): The abnormal NMMHC-IIA aggregates can be detected via immunofluorescent test. Screening for MYH9-RD using this relatively simple approach is useful when genetic testing is not easily available. Identifying patients with MYH9-RD is important to give them a correct diagnosis and prevent unnecessary/harmful treatments such as steroids and splenectomy in cases of suspected autoimmune thrombocytopenia. Further testing would be required to confirm the genetic origin of this condition.