Thread: HCM gene testing- are we wasting our time?

Here is the abstract of the most recent HCM paper I am aware of, directed specifically at hetero MCs:

J Vet Intern Med 2009;23:91–99

P r o s p e c t i v e Ec h o c a r d i o g r a p h ic an d T i s s u e D o p p l e r Im a g i n g
Scr eening o f a Popul ation of Maine C oon Cats T ested f or the A31P
Mu t a t i o n i n t h e M y o s i n - B i n d i n g P r o t e i n C G e n e :
A S p e c i fi c An a l y s i s of the H ete roz ygous Status

C. Carlos Sampedrano, V. Chetboul, J. Mary, R. Tissier, M. Abitbol, F. Serres, V. Gouni, A. Thomas, and J.-L. Pouchelon

Background: A mutation in the sarcomeric gene coding for the myosin-binding protein C gene has been identified in a
colony of Maine Coon cats with hypertrophic cardiomyopathy (MyBPC3-A31P mutation). However, the close correlation
between genotype and phenotype (left ventricular hypertrophy [LVH] and dysfunction) has never been assessed in a large pop-
ulation, particularly in heterozygous (Hetero) cats.

Objectives: To investigate LV morphology and function with echocardiography and tissue Doppler imaging (TDI) in a
population of Maine Coon cats tested for the MyBPC3-A31P mutation with focus on Hetero animals.

Animals: Ninety-six Maine Coon cats.

Methods: Prospective observational study. Cats were screened for the MyBPC3-A31P mutation and examined with both
echocardiography and 2-dimensional color TDI.

Results: Fifty-two out of 96 cats did not have the mutation (wild-type genotype, Homo WT), 38/96 and 6/96 were
Hetero- and homozygous-mutated (Homo M) cats, respectively. Only 11% of Hetero cats (4/38) had LVH and 29% (10/34) of
Hetero cats without LVH were >4 years old (4.1–11.5 years). LVH was also detected in 2 Homo WT cats (4%). A significantly
decreased (P < o .05) longitudinal E/A (ratio between early and late diastolic myocardial velocities) in the basal segment of
the interventricular septum was observed in Hetero cats without LVH (n = 34) compared with Homo WT cats without LVH
(n = 50), thus confirming that the Hetero status is associated with regional diastolic dysfunction (P < o .05).

Conclusions: The heterozygous status is not consistently associated with LVH and major myocardial dysfunction. More-
over, Homo WT cats can also develop LVH, suggesting that other genetic causes might be implicated.

This is quite a bit more positive paper about hetero MCs than the earlier papers. This paper did not follow cats to see when they died, though, it just looked for evidence of HCM-related heart changes at some (not very old) ages. Real question is average lifespan of clear (homo WT) vs. hetero M vs. homo M cats. This would be a very expensive undertaking with no financial benefits to any sort of drug company, so unlikely to ever be carried out.