Early Onset Muscle Weakness Syndrome Officially Recognized as Undesirable Genetic Condition by HAUSA

Holstein Association USA (HAUSA) has declared Early Onset Muscle Weakness Syndrome (MW) as an officially recognized genetic condition, beginning in February 2024. This decision is supported by the HAUSA Board of Directors, Genetic Advancement Committee, staff, Holstein breeders and scientific researchers. Haplotype calls for MW were first released by CDCB in the December 2023 genetic evaluations and will continue to utilize MW test results received by HAUSA which are shared with CDCB for this collaborative effort.

Starting in late February 2024, direct gene test results for MW will be labeled on Official Holstein Pedigrees, and other products where officially recognized genetic conditions are displayed. The recessive files shared by CDCB with industry collaborators as a part of the April 2024 evaluations will include MW gene test results for males.

These codes will designate animals with official gene test results in the recessive file:

• TE = tested free of MW
• MW = Heterozygous Carrier
• MW2 = Homozygous Carrier

Haplotype calls for the condition, reported as HMW, will continue to be included in CDCB genomic evaluations as:

• 0 = noncarrier
• 1 = carrier
• 2 = homozygous
• 3 = probable carrier
• 4 = probable homozygous

Breeders are encouraged to forward all gene test results, including those for MW, to labresults@holstein.com to advance the understanding of conditions and improve the accuracy of haplotype calls. Routine, continuous streams to confidentially share gene test results for MW, as well as Cholesterol Deficiency (CD), are in place between HAUSA and CDCB for research and improvement of haplotype calls.