Chromosomal Mutations & their

effects

Karyotype• A picture of the chromosomes of an

individual or a species, including number, form, and size of the chromosomes.

• Often used to diagnosis chromosomal abnormalities.

Chromosomes

• Humans have 23 pairs– 22 pairs are autosomes– 1 pair are sex chromosomes

•(women = XX, men = XY)• Chromosomes have a centromere that

holds the chromatids (two parts of the chromosome) together.

• The top ½ of the chromosome is called the “p” arm and the bottom ½ is “q”

Nondisjunction Disorder

• Nondisjunction is the failure of chromosome pairs to separate during meiosis (making of gametes – sex cells)

• it can cause some gametes to gain an extra chromosome and others to lose one

• Monosomy = A chromosome having no homologue (matching chromosome)

• Trisomy =The condition of having three copies of a given chromosome in each somatic (body) cell rather than the normal number of two.

Normal Male Karyotype

Normal Female Karyotype

Turners Syndrome

1 in 5,000 births

45 chromosomesX only #23 MonosomyNondisjunction

Turners Syndrome96-98% do not survive to birthNo menstruationNo breast developmentNo hipsBroad shoulders and neck

Cri-Du-Chat Syndrome

1 in 216,000 births

46 chromosomesXY or XX

#5 Deletion of upper arm of chromosome

Cri-Du-Chat SyndromeMoon-shaped faceHeart diseaseMentally retardedMalformed larynxNormal lifespan

Aniridia-Wilms Tumor Syndrome

1 in 50,000,000 births

46 chromosomesXY or XX

#11 Deletion of upper arm

Aniridia-Wilms Tumor Syndrome

Mentally retardedGrowth retardedBlindnessTumors on kidneysShort lifespan

Thirteen Q Deletion Syndrome

1 in 500,000 births

46 chromosomesXY or XX

#13 Deletion of lower arm

Thirteen Q Deletion Syndrome

Mentally retarded Deformed faceNo thumbs Heart diseaseShort lifespan

Prader-Willi Syndrome

1 in 5,000,000 births

46 chromosomesXY=97% XX=3%

#15 Deletion of lower arm

Prader-Willi SyndromeSmall bird-like headMentally retardedRespiratory problemsObesityShort lifespan

Eighteen Q Deletion Syndrome

1 in 10,000,000 births

46 chromosomesXY or XX

#18 Deletion of lower arm

Eighteen Q Deletion Syndrome

Mentally retardedHeart diseaseAbnormal hands and feetLarge eyesLarge earsNormal lifespan

Cat-Eye Syndrome1 in 1,000,000 births

46 chromosomesXY or XX

#22 Deletion of bottom arm

Cat-Eye SyndromeFused fingers and toesMentally retardedSmall jawHeart problemsNormal lifespan

Four-Ring Syndrome

1 in 10,000,000 births

46 chromosomesXY or XX

#4 Inversion

Four-Ring Syndrome

Cleft palateClub feetTestes don’t descendShort lifespan

Down Syndrome

1 in 31,000 births

46 chromosomesXY=97%

XX=3%

#14/21 Translocation

1 in 1,250 births

47 chromosomesXY or XX

#21 Trisomy Nondisjunction

Down Syndrome Trisomy

Down Syndrome

Short, broad hands Stubby fingersRough skinImpotency in malesMentally retardedSmall round faceProtruding tongueShort lifespan

Patau’s Trisomy Syndrome

1 in 14,000 births

47 chromosomesXY or XX

#13 Trisomy Nondisjunction

Patau’s Trisomy Syndrome

Small headSmall or missing eyesHeart defectsExtra fingersAbnormal genitaliaMentally retardedCleft palateMost die a few weeks after birth

Edward’s Trisomy Syndrome

1 in 4,400 births

47 chromosomesXX=80%

XY=20%

#18 Trisomy Nondisjunction

Edward’s Trisomy Syndrome

Small headMentally retardedInternal organ abnormalities90% die before 5 months of age

Jacob’s Syndrome1 in 1,800 births

47 chromosomesXYY only

#23 Trisomy Nondisjunction

Jacob’s Syndrome

Normal physicallyNormal mentallyIncrease in testosteroneAcneNormal lifespan

?

Kleinfelter Syndrome1 in 1,100 births

47 chromosomesXXY only

#23 Trisomy Nondisjunction

Kleinfelter SyndromeScarce beardLonger fingers and armsSterileDelicate skinLow mental abilityNormal lifespan

Triple X Syndrome

1 in 2,500 births

47 chromosomesXXX only

#23 TrisomyNondisjunction

Triple X Syndrome

Normally physically Normal mentallyTallFertilenormal lifespan