When these new genes are arranged in the chromosomes, there is possibility that they
arrange in an order where two genes with opposing properties (like tall and short) may
come to stay near each other, and these are known as alleles. It is being increasingly
recognized that all human characters including diseases are determined by genes, and
chromosomes are not identical, and they have specific locations for individual genes.
Applying the same genetic principles, alleles in a chromosome locus or position may be
held responsible since diseases are either expression of genetic reactions in the body or
expression of environmental factors like bacteria or toxins on the human cells.
Most human genetic disorders are determined by recessive allele. Presence of
dominant and recessive alleles was first determined by Gregor Mendel. Normal alleles
usually are dominant and mutant alleles, recessive. In this way, the chances of an
offspring being affected by a disease can be predicted by the study of the alleles of the
parents. This process has lead to the concept of genetic counseling; Medicine owes this to
mendelian principles since genetic counseling is totally based upon mendelian genetics
and probability rules. The development of this process involves analysis of fetal samples
by amniocentesis in a pregnant mother (Audesirk, T. and Audesirk, G, 1996).
Alkaptonuria is a genetic disorder where dysmetabolism is noticeable
by discoloration of urine when exposed to air, and these children would have died
prematurely with brain disorders. The gene therapy for this disease was easily discovered
when it was found that this disease is...
gene n."The Concise Oxford English Dictionary, Eleventh edition revised . Ed. Catherine Soanes and Angus Stevenson. Oxford University Press, 2006. Oxford Reference Online. Oxford University Press.British Council Delhi.29 April 2007