Updated by: Arabinda Naik
It is a type of sex-linked inheritance where the genes of one parent are transferred to the grand children through children of opposite sex. When a male has a defective sex-linked gene located on X chromosome, he transmits the defective X chromosome to her daughter only. The female who has this gene transmits it to her son and daughter. The sex-linked trait being recessive is not expressed in female but expressed in males. Therefore, males suffer from the genetic defect due to presence of faulty gene on single X chromosome while female are carriers of these defective gene as they have the other X which masks the effect of faulty gene. Red, green colour blindness and Haemophilia are example of sex-linked inheritance. The defective gene is located on X chromosome. Thus, a single defective gene cause disease in male while two defective gene only can cause the disease in female. Female in heterozygous condition is normal but the career of the disease. The disease is expressed only in males because male does not have the partner of such defective gene on Y chromosome to mask the effect of faulty gene.