Question

A couple brought their child Tom (with DMD, Duchene Muscular Dystrophy) to test for the presence of the mutation (missing Exon 53) in his mother (carrier testing). They are seeking genetic counseling prior to planning their next child. Which molecular methodology is appropriate for carrier testing in this case? Present a schematic representation and explain the possible expected results for the mother.

Answer 1

• Duchene Muscular Dystrophy is a sex linked diorder.
• It can be diagonised by MLPA (Multiplex Ligation dependent Probe Amplification) followed by direct sequencing of all exons at the genomic level, inorder to detect point mutations.

Cross Father Mother

Parents Phenotype- Normal DMD carrier

Genotype- XY XXD

Progenies: XX , XXD, XY, XDY

Unaffected female carrier female unaffected male affected male

50% of male progenie have got chance of getting DMD

50% of female progenies have got chance to be carriers

50% of female and male are exactly normal