4 Modes of Inheritance Autosomal or Sex-Linked Dominant or Recessive Autosomal –chromosomes other than sex chromos.Sex linked – X or YDominant or Recessive
5 Autosomal Recessive ~equal in males & females Often skips generations May show carriers (half shaded) but not always!
6 Autosomal Dominant Does not skip generations Affect crossed with unaffected = 50% of offspring are typically affected
7 Sex-Linked Traits Mostly males Mother of affected male is a carrier or affected.No male carriers, but can have female carriers
8 Pedigree Flowchart How many males & females are affected? More Males Males = Affected FemalesAutosomalMore MalesSex Linked TraitNo male carriers?No:Does the trait skip a generation?Are carriers present?Yes:RecessiveNo: DominantYes: Recessive8
9 Human Karyotypes Diploid organisms 46 Chromosomes 23 homologous pairs 2 sex chromos.Used to detectedaneuploidy associateddisorders
10 Nondisjunction Not coming apart Abnormal chromosome #s in gametes Causes: Aneuploidy
11 Down Syndrome Trisomy Chromosome 21 1/800 US births Mild – severe Three bodiesChromosome 21autosomal1/800 US birthsMild – severe
12 Sex Chromosomes Disorder Turner’s SyndromeFemale with only one XXOCauses Sterility = no sex organ development at pubertyShort statureWebbed neckcommon feature of Turner syndrome is short stature, which becomes evident by about age 5. An early loss of ovarian function (ovarian hypofunction or premature ovarian failure) is also very common.Many affected girls do not undergo puberty unless they receive hormone therapy, and most are unable to conceive (infertile)About 30 percent of females with Turner syndrome have extra folds of skin on the neck (webbed neck), a low hairline at the back of the neck, puffiness or swelling (lymphedema) of the hands and feet, skeletal abnormalities, or kidney problems. One third to one half of individuals with Turner syndrome are born with a heart defect, such as a narrowing of the large artery leaving the heart (coarctation of the aorta) or abnormalities of the valve that connects the aorta with the heart (the aortic valve).
13 Klinefelter’s Syndrome Males with an extra XReduced fertilityLess testosterone1/1000 malesXYYNormal reproductionDelay motor skillstemperKlinefeltersdo not produce as much testosterone as usual shortage of testosterone can lead to delayed or incomplete puberty, breast enlargement (gynecomastia), reduced facial and body hair, and an inability to have biological children (infertilityOlder children and adults with Klinefelter syndrome tend to be taller than their peers. Compared with unaffected men, adults with Klinefelter syndrome have an increased risk of developing breast cancer and a chronic inflammatory disease called systemic lupus erythematosus. Their chance of developing these disorders is similar to that of women in the general population.Children with Klinefelter syndrome may have learning disabilities and delayed speech and language development. They tend to be quiet, sensitive, and unassertive, but personality characteristics vary among affected individuals.XYYAlthough males with this condition may be taller than average, this chromosomal change typically causes no unusual physical features. Most males with 47,XYY syndrome have normal sexual development and are able to father children.47,XYY syndrome is associated with an increased risk of learning disabilities and delayed development of speech and language skills. Delayed development of motor skills (such as sitting and walking), weak muscle tone (hypotonia), hand tremors or other involuntary movements (motor tics), and behavioral and emotional difficulties are also possible. These characteristics vary widely among affected boys and men.
14 X Chromosome No cases of babies born without an X chromosome X is vital for normal development
15 Y Chromosome Important role in sex determination Y presence creates a male no matter how many extra XsException : Swyer syndromeSRY gene mutations that cause Swyer syndrome prevent production of the sex-determining region Y protein or result in the production of a nonfunctioning protein. A fetus whose cells do not produce functional sex-determining region Y protein will develop as a female despite having a Y chromosome.