1. Chromosomal Disorders

2. Down Syndrome 47 chromsomes 1/700 births
3 x #21 nondisjunction of chromosome 21
Short, broad hands with palmar crease, short stature, hyper-flexibility of joints, mental retardation, broad head with round face, open mouth with large tongue.

3. Cri-du-Chat 46 total chromosomes Upper arm deletion on chromosome #5
“Cry of the cat” severely impaired- both mentally and physically, their plaintive, catlike crying gives the syndrome its name.

4. Edwards Syndrome 47 chromosomes 1/8000 births
Nondisjunction of chromosome # 18.
Congenital malformation of many organs. Low-set malformed ears, receding mandible, small mouth and nose with general elfin appearance, mental deficiency, horseshoe or double kidney, short sternum, 90% die within the first 6 months after birth

5. Patau Syndrome 47 chromosomes 1/20,000 births
Nondisjunction of chromosome #13.
Mental deficiency and deafness, minor muscle seizures, cleft lip and/or palate, cardiac anomalies, posterior heel prominance

6. Turner Syndrome 45 chromosomes 1/2500 female births
Monosomy of chromosome X.
Female, but almost always sterile. Short in stature, webbing in neck region, hearing deficiencies, and significant cardiovascular abnormalities

7. XXX- Triplo X Syndrome 47 chromosomes 1/700 female births
Trisomy of chromosome 23
Female, phenotypically normal, limited fertility, may have slight mental retardation

8. Klinefelter Syndrome 47 chromosomes 1/500 male births
Nondisjunction of chromosome 23. XXy
Male, subfertile with small testes, developed breasts, feminine pitched voice, knock knees, long limbs.

9. Jacob’s Syndrome 47 chromosomes 1/1000 male births
Xyy- nondisjunction of chromosome 23
Male- tend to be taller than normal. Most have normal sexual development and able to father children. May have increased risk of learning disabilities, delayed speech and gross motor skills. Some linked to Autism. Not inherited.