Abstract:
We researched hypertrophic cardiomyopathy (HCM) and
long QT syndrome (LQTS) as models for studying the
pathophysiology of arrhythmias and hypertrophy, and in the
process we have had the opportunity to compare local disease
profiles with global patterns.
We trawled our database entries over the past 20 years
to identify all cases of heart muscle and arrhythmic disease.
Among these, we separated the index cases from the rest
of their family members, segregating for the relevant heart
disease, so that numbers were not biased by family size, and
analysed the race and gender composition of the HCM and
LQTS sectors.
The majority of HCM index cases (n = 5 90, 51.1% of HCM
index cases) were of mixed ancestry (MA), with white Caucasian
ancestry following closely behind with 74 cases (42.0%);
only a few black African (n = 5 9, 5.1%) or I ndian/Asian (n = 5
3, 1.7%) cases were seen or referred. The LQTS index cases
were almost exclusively white Caucasian (n = 5 36, 88% of
LQTS index cases), with four cases (9.8%) of MA, one (2.4%)
of Indian/Asian and none of black African descent. These
race demographics did not fit the national demographics for
South Africa as a whole. In contrast, in both groups, gender
biases (slightly more male than female HCM cases, and a
0.4 ratio of males to females in LQTS) previously reported
elsewhere appeared to be replicated in our database.
Genetic bias is an unlikely explanation for the skewed
demographics in our database; a more likely explanation
relates to various missed opportunities to diagnose, missed
diagnoses and misdiagnoses, as well as the real population
drainage of our main referral centre in the context of a
differentiated healthcare system.
