Duchenne Muscular Dystrophy. Duchenne muscular dystrophy (DMD), or Meryon’s disease, is a genetically transmitted disease, passed from a mother to her children (Fig. 2.20). Affected female offspring usually suffer no apparent symptoms and may unknowingly carry the disease. Male offspring with the disease die at a young age. Not all cases of the disease come from an affected mother. A fraction, perhaps one third, of the cases arise spontaneously, to be genetically transmitted by an affected female. This is the most widely held view at present. The incidence of DMD is about 1 in 10,000 male births. The population risk (prevalence) that a woman is a DMD carrier is about 3 in 10,000.
From the text page download data set dmd. dat|mat|xls. This data set is modified data from Percy et al. (1981) (entries containing missing values
excluded). It consists of 194 observations corresponding to blood samples collected in a project to develop a screening program for female relatives of boys with DMD. The program was implemented in Canada and its goal was to inform a woman of her chances of being a carrier based on serum markers as well as her family pedigree. Another question of interest was whether age should be taken into account. Enzyme levels were measured in known carriers (67 samples) and in a group of noncarriers (127 samples). The first two serum markers, creatine kinase and hemopexin (ck,h), are inexpensive to obtain, while the last two, pyruvate kinase and lactate dehydroginase (pk,ld), are expensive. The variables (columns) in the data set are
(a) Find the mean, median, standard deviation, and real MAD of pyruvate kinase level, pk, for all cases (carrier=1).
(b) Find the mean, median, standard deviation, and real MAD of pyruvate kinase level, pk, for all controls (carrier=0).
(c) Find the correlation between variables pk and carrier.
(d) Use MATLAB’s gplotmatrix to visualize pairwise dependencies between the six variables.
(e) Plot the histogram with 30 bins and smoothed normalized histogram (density estimator) for pk. Use ksdensity.