Human Genetics

Chromosomal Disorders Nondisjunction – means “not coming apart”; when homologous chromosomes fail to separate, abnormal chromosome numbers may find their way into gametes Monosomy – missing one chromosome from a pair Trisomy – having three copies of a chromosome Ex] Trisomy 21 – extra chromosome-21

A karyotype displays a diploid number of chromosomes. Analyzing Karyotypes A karyotype displays a diploid number of chromosomes.

How Are Karyotypes Made?

Human Female Karyotype Human Karyotypes Human Female Karyotype Notation: 46, XX Autosomes Sex Chromosomes Notation: 46, XY

Karyotype Analysis Is this person a male or a female?   What condition does this person have? Trisomy 21 / Downs Syndrome What was it caused by? Nondisjunction  What notation would you use to characterize this patient’s karyotype? 47, XY, +21

Recognizing Disorders in Karyotypes

Patient 1

Patient 2 Turner’s Syndrome

Patient 2 Short stature (height) Failure of ovaries to develop Abnormal fingernails and toenails. Kidney and urinary tract disorders. Hearing problems. Drooping eyelids. Wandering eyes.

Patient 3 Cri-Du-Chat

Cri Du Chat Patient 3 Cry is high-pitched so it sounds like a cat. Low-set or abnormally shaped ears. Mental retardation Webbed fingers and toes. Small head Wide-set eyes

Patient 4 Klinefeleter’s Syndrome

Patient 4 Very little body hair. Underdeveloped muscles Enlarged breasts Reduced speech ability Reduced problem-solving skills. Trouble with controlling impulses

XXX Syndrome Patient 5 Very tall Often has learning disabilities Delayed learning in speech, language. Delayed motor skills.

Patient 5

Trisomy 13: Patau’s Syndrome Patient 6 Trisomy 13: Patau’s Syndrome

Patient 6 Extra fingers and toes Deformed, rocker-bottom feet. Severe mental deficiency due to underdeveloped brain. Facial deformation such as cleft palate. Heart and Kidney defects.

Trisomy 18: Edward’s Syndrome Patient 7 Trisomy 18: Edward’s Syndrome

Edward’s Syndrome Patient 7 Mental retardation Small head, very wide-set eyes, small lower jaw. Small eyes. Bones are severely retarded in their growth (they grow slowly) Urinary tract, digestive tract, and genitals are malformed.

Patient 8 Trisomy 21: Down’s Syndrome

Down’s Syndrome Patient 8 Flat face with an upward slant to the eye, short neck, and abnormally shaped ears. Hearing problems. Heart disease Intestinal problems Thyroid dysfunctions Skeletal problems Dementia