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Growth & Development

  Heredity & Environment
- Inherited Abnormalities -

Growth & Development

Ψ  Chromosomal Miscount - usually results in spontaneous abortion (miscarriage). An estimated half of all zygotes have an odd number of chromosomes.

Ψ  Most zygotes with chromosomal abnormalities are aborted; but, one in 200 are born & in every case have a recognizable syndrome, such as:
•  Down syndrome: Trisomy - 21, most common extra-chromosome syndrome
 •  Klinefelter syndrome (23 location), impairs sexual maturation
  •  Fragile X syndrome - most common form of inherited mental retardation.

Ψ  The variable that most often correlates with chromosomal abnormalities is maternal age.

Ψ  Some methods of genetic testing follow:
 •  PKU or Phenylketonuria (every newborn in the US is tested)
   •  Alpha-Fetoprotein Assay
     •  Chorionic villi Sampling (CVS)
       •  Amniocentesis (reveals sex of the fetus)
         •  Ultrasound (sonogram)

It's a Mickey Mouse World , isn't it?

Harmful Genes

Dominant disorders:
         •  Huntington's Chorea - central nervous system disease
          •  Tourette's Syndrome - tics & twitches, sometimes with uncontrollable speech
                             •   Link to more information on Huntington's Disease. User Friendly
Recessive disorders:
         •  Cystic Fibrosis
          •  Thalassemia
           •  Sickle-cell Anemia

Ψ  Genes that predispose for schizophrenia occur on chromosomes 1,5,6,10,13,15, & 22.

Ψ  Genetic counseling is the process of helping people understand & adapt to the medical, psychological & familial implications of genetic contributions to disease. This process integrates the following:
•  Interpretation of family & medical histories to assess the chance of disease occurrence
   or recurrence.
 •  Education about inheritance, testing, management, prevention, resources & research.
  •  Counseling to promote informed choices and adaptation to the risk or condition.

Growth & Development
Robert C. Gates