Father to son inheritance is never seen in case of:
Ans. is 'c' i.e. X linked recessive inheritance X linked recessive inheritance is a sex linked disorders i.e. they are transmitted by sex chromosomes. Remember that all sex linked diseases are linked to X chromosome so it is quite obvious that none of the sex linked disease (whether X-linked recessive or X-linked dominant) will be transmitted from father to son, as father transmits only 'Y' chromosome to the son.Other characteristic of this disorder is that it is mostly seen in males. Where as the diseases transmitted through non sex. Chromosomes (autosomes) have equal male and female incidence.So it is clear from the figureAn affected male does not transmit the disorder to his sons, but all daughters are carriersSons of heterozygous woman have 50% choice of receiving the abnormal geneIt usually affects males because of the presence of Y chromosome which is not homologous to X chromosome and therefore the mutant genes on the X is not paired with alleles on the YIt is rare in females only possible when mother is carrier and father has overt disease.* Most of the X linked disorders or X linked recessive. There are only few X-linked dominant conditions. These arePseudonym aparathyroidism Hypophosphatemic rickets*.Example of X-linked recessive disordersDuchenne muscular dystrophy *Hemophilia A and B*Chronic granulomatous diseaseGlucose 6-PO4 dehydrogenase deficiency*AgammaglobulinemiaWiskott Aldrich syndrome*Diabetes insipidus*Fragile X syndrome*Lesch Nyhan syndrome
Autosomal dominant inheritance
Autosomal recessive inheritance
X- linked recessive inheritance
Multifactorial inheritance
General