Brian is 15 months old. He has recently been was diagnosed with X-linked ichthyosis. He is in the clinic with his family

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Brian is 15 months old. He has recently been was diagnosedwith X-linked ichthyosis. He is in the clinic with his family toreceive the results of the genetic testing. The testing has beendone to find out if Brian has an inherited or sporadic form of thedisorder. Faisal and Nadia, Brian’s parents, are worried becausethey are expecting their second child, another boy, in about 3months. Nadia’s medical notes reveal that she experiencedsignificant post-natal depression after Brian’s birth. Theclinician informs them that Nadia is a carrier of a causativemutation and asks them for a family history.
Nadia explains that she has an older sister and that hermother miscarried a baby at about 16 weeks before going on toconceive Nadia. Nadia’s sister is married and has one healthydaughter aged 6. Nadia and her sister lost contact with theirmother after she left their dad, but they are still in touch withtheir maternal grandmother, Lily, who has an identical twin,Hannah. Lily and Hannah both married young and each had twochildren. Hannah had a girl, then a boy and Lily had a boy, then agirl. Nadia tells you that Lily’s son, Leo (Nadia’s maternal uncle)died very young but that she doesn’t know what of because Lily didnot like to speak of it. Nadia tells you that her grand-maternalAunt Hannah’s youngest child, Eman, has Down Syndrome. He livesquiet and independent life in supported housing. Eman’s oldersister, Pearl, didn’t marry but had two daughters by two differentfathers. The first daughter has twins (runs in the family). Nadiasees the younger daughter, Asma, quite often; they are going toanti-natal classes together. Asma has one son who is aged 7 and isexpecting another boy about a month after Brian’s brother isborn.
The clinician asks if Nadia would be willing to disclose hergenetic status to her wider family. She says that she is willing.Then the clinician asks if Nadia will supply contact details forLily, Asma and Jo, to enable the hospital to contact them and askthem to consider genetic testing for the X-linked ichthyosiscausing mutation. Nadia agrees. She doesn’t have details for Jo,but she will ask Asma. The clinician explains that Asma’s oldersister should be informed too and anyone else who might be acarrier. Nadia is unable to say whether her mother has had morechildren.
Faisal informs you that he is red-green colour-blind andasks if that matters. You draw the fully annotated pedigree for theclinician and genetic counsellor to use in this case.
(question) With reference to the story aboveand the pedigree diagram that you have produced: What is theapproximate percentage chance that Asma’s unborn son will exhibitthe X-linked ichthyosis phenotype due to inheriting the causativemutation, if it was carried by Brian’s maternal great-grandmother?Please give your answer as a PERCENTAGE TO ONE DECIMALPLACE