A boy with Klinefelter syndrome (47,XXY) is born to a motherwho is phenotypically normal and a father who has the X-linkedskin condition called anhidrotic ectodermal dysplasia. The mother’sskin is completely normal with no signs of the skin abnormality.In contrast, her son has patches of normal skin and patchesof abnormal skin. Using the appropriate genetic terminology, explain theson’s skin phenotype.

A boy with Klinefelter syndrome (47,XXY) is born to a motherwho is phenotypically normal and a father who has the X-linkedskin condition called anhidrotic ectodermal dysplasia. The mother’sskin is completely normal with no signs of the skin abnormality.In contrast, her son has patches of normal skin and patchesof abnormal skin. Using the appropriate genetic terminology, explain theson’s skin phenotype.

Human Heredity: Principles and Issues (MindTap Course List)

11th Edition

ISBN:9781305251052

Author:Michael Cummings

Publisher:Michael Cummings

Chapter4: Pedigree Analysis In Human Genetics

Section: Chapter Questions

Problem 22QP: Analysis of X-Linked Dominant and Recessive Traits In the eighteenth century, a young boy with a...

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A boy with Klinefelter syndrome (47,XXY) is born to a motherwho is phenotypically normal and a father who has the X-linkedskin condition called anhidrotic ectodermal dysplasia. The mother’sskin is completely normal with no signs of the skin abnormality.In contrast, her son has patches of normal skin and patchesof abnormal skin. Question: Which parent contributed the abnormal gamete?
A woman who sought genetic counseling is found to be heterozygousfor a chromosomal rearrangement between the second andthird chromosomes. Her chromosomes, compared to those in anormal karyotype, are diagrammed on the next page:(a) This woman is phenotypically normal. Does thissurprise you? Why or why not? Under what circumstancesmight you expect a phenotypic effect of such arearrangement?
A boy with Klinefelter syndrome (47,XXY) is born to a motherwho is phenotypically normal and a father who has the X-linkedskin condition called anhidrotic ectodermal dysplasia. The mother’sskin is completely normal with no signs of the skin abnormality.In contrast, her son has patches of normal skin and patchesof abnormal skin. Question: Using the appropriate genetic terminology, describe themeiotic mistake that occurred. Be sure to indicate in whichdivision the mistake occurred.
Duchenne muscular dystrophy is a recessive disorder caused by a rare,loss-of-function allele that is located on the X chromosome in humans. Anunaffected woman (i.e., without disease symptoms) who is heterozygousfor the X-linked allele causing Duchenne muscular dystrophy has childrenwith a man with a functional (non-disease-causing) allele. What is theprobability that this couple will have an unaffected son?
When examining a human pedigree, what features do you look forto distinguish between X-linked recessive inheritance and autosomal recessive inheritance? How would you distinguish X-linkeddominant inheritance from autosomal dominant inheritance in ahuman pedigree?
The maternal-effect mutation bicoid (bcd) is recessive. Inthe absence of the bicoid protein product, embryogenesis isnot completed. Consider a cross between a female heterozygousfor the bicoid mutation (bcd+/ bcd-) and a homozygousmale(bcd-/ bcd-). How is it possible for a male homozygous for the mutationto exist?
Researchers discovered recently that the sole functionof the SRY protein is to activate an autosomal genecalled Sox9 in the presumptive gonad (before it has“decided” to become a testis or an ovary).a. What would be the sex of an XY individual homozygous for nonfunctional mutant alleles of Sox9?Explain.b. Given your answer to part (a), why is SRY, ratherthan Sox9, considered the male determining factor?(Hint: What do you think would happen if you didan experiment like the one in the Fast Forward BoxTransgenic Mice Prove That SRY Is the MalenessFactor, except that you used a Sox9 transgeneinstead of SRY?)
Galactosemia is a recessive human disease that istreatable by restricting lactose and glucose in the diet.Susan Smithers and her husband are both heterozygous for the galactosemia gene.a. Susan is pregnant with twins. If she hasfraternal (nonidentical) twins, what is theprobability both of the twins will be girls whohave galactosemia?b. If the twins are identical, what is the probabilitythat both will be girls and have galactosemia?For parts (c–g), assume that none of the children isa twin.c. If Susan and her husband have four children, whatis the probability that none of the four will havegalactosemia?d. If the couple has four children, what is the probability that at least one child will have galactosemia?e. If the couple has four children, what is the probability that the first two will have galactosemia andthe second two will not?f. If the couple has three children, what is the probability that two of the children will have galactosemia and one will not, regardless of order?g. If…
A karyotype shows that a child has Klinefelter syndrome (47,XXY). If the child is also colorblind (due to a recessive X-linked allele), despite his parents having normal color vision, in which parent and stage of meiosis did nondisjunction occur? And explain why .
Campomelic dysplasia (CMD1) is a congenital humansyndrome featuring malformation of bone and cartilage.It is caused by an autosomal dominant mutation of agene located on chromosome 17. Consider the followingobservations in sequence, and in each case, draw whateverappropriate conclusions are warranted.(a) Of those with the syndrome who are karyotypically46,XY, approximately 75 percent are sex reversed,exhibiting a wide range of female characteristics.(b) The nonmutant form of the gene, called SOX9, isexpressed in the developing gonad of the XY male,but not the XX female.(c) The SOX9 gene shares 71 percent amino acid codingsequence homology with the Y-linked SRY gene.(d) CMD1 patients who exhibit a 46,XX karyotypedevelop as females, with no gonadal abnormalities.
Two mothers give birth to sons at the same time at a busy urbanhospital. The son of mother 1 has hemophilia, a disease causedby an X-linked recessive allele. Neither parent has the disease.Mother 2 has a son without hemophilia, despite the fact thatthe father has hemophilia. Several years later, couple 1 suesthe hospital, claiming that these two newborns were swappedin the nursery following their birth. As a genetic counselor, youare called to testify. What information can you provide the juryconcerning the allegation?
Assuming no other abnormalities, classify each of the following human sex chromosome complements as to whether or not individuals with that complement will be morphologically male or female. Three human sex chromosome complements will be classified as male and three will be classified as female. XXY XYY XXX XO XY XX