Question

The genes for ABO blood group is located on _______
A. Chromosome 4
B. Chromosome 7
C. Chromosome 9
D. Chromosome 11

Answer 1

ABO gene has multiallelic- three alleles: A, B, and O. The three alleles of this blood group are $I^A$, $I^B$, i. These alleles are present on the autosomal chromosome and show a Mendelian pattern of inheritance.

Complete answer: The ABO gene is present on the long arm of chromosome 9. ABO encodes for ABO histo-blood group glycosyltransferase. It also has genes like ACTL7A encoding protein like actin protein A, ANGPTL2 coding for angiopoietin related protein-2, CAAP1 coding for caspase activity and apoptosis inhibitor 1, etc.
-Chromosome 4 has around 1000 to 1100 genes. Some of the genes located on chromosome 4 are ANK2 coding for neuronal ankyrin 2, CRMP1 coding for collapsin response mediator protein 1, FGFR3, and FGFR1 coding for fibroblast growth factor receptor 1 and 3. It also codes for complement 1, cytokines, platelet factor 4, interleukin 8, etc. It also codes for Huntington protein.
-Chromosome 7 has around 948 protein-coding genes. Some of which are ACTR3B coding for actin-related protein 3B, BCAP29 coding B cell receptor-associated protein 29, AEBP1 coding for AE binding protein, MAP11 coding for microtubule-associated protein 11, DMTF1 coding for cyclin D binding myb like transcription factor 1, MTERF1 coding for mitochondrial transcription termination factor 1, etc. genetic mutations in chromosome 7 can lead to diseases like Maple syrup urine disease, muscular dystrophy, hemochromatosis type 3, Zellweger syndrome, Schizophrenia, Williams syndrome, etc.
-Chromosome 11 has around more than 1000 genes. Gene mutation in chromosome 11 can lead to any diseases like cystic fibrosis, sickle cell anemia, porphyria, autism, bladder cancer, etc.
Hence, the correct answer is an option (C).

Note: The A allele encodes for α-1,3-N-acetylgalactosamine transferase which transfers GalNac to Gal on H antigen. Allele B encodes for α-1,3-galactosyl transferase that transfers Gal to H antigen. O allele does not code for any transferase enzyme.