In pedigree analysis symbol ⨀ is used for A. Heterozygous for autosomal recessive B. Affected individuals C. Death D. Carrier for sex-linked recessive
Hint: In pedigree chart, a clear circle shows a female individual. A half-shaded symbol or a dot in the middle of a symbol can represent a carrier of different genes.
Complete answer: Pedigree analysis is a method devised by scientists to study the inheritance of genes in humans. From several generations, the exact phenotypic data is collected (as much as possible), and then a pedigree is drawn which looks like a chart. A careful insight or analysis of this chart allows scientists or analysts to determine whether a particular trait is dominant or recessive. In the pedigree analysis, specific symbols are used to denote different features. These are used while drawing a pedigree. Some of the basic symbols and their meanings are:
Additionally, a dot in a circle (⨀) shows an individual who is a carrier for a sex-linked recessive gene.
So, the correct option is D. Carrier for sex-linked recessive.
Note: In pedigree analysis, each row indicates a generation. The individual who brought the family to the attention of the pedigree analyst or researcher is called a ‘proband’. The proband can be identified by an arrow pointing towards the individual (the symbol which shows him/her).