Achondroplasia

1
Achondroplasia

• Presentation by
• Sarah Maas, Isabelle McKusick and Betty House
• November 16, 2005

2
What is Achondroplasia?

• Achondroplasia is an autosomal dominant condition
• It was discovered in 1994 by Dr. John Wasmuth
• It is caused by a mutation of the fibroblast
  growth factor receptor-3 (FGFR3) gene on
  chromosome 4.
• Achondroplasia is the most common form of
  Dwarfism
• Although there are over 200 types of dwarfism,
  two-thirds have achondroplasia
• It affects 1 in 25,000
• 30,000 to 50,000 in U.S. have some form of
  Dwarfism
• It occurs in both sexes and all races
• Motor skills are temporarily delayed
• Cognitive skills/intelligence levels are not
  affected

3
Characteristics

• Characteristic features are evident at birth
• Head is large, forehead is prominent
• Hydrocephalus (excess fluid on the brain) may
  present
• Protruding jaw, poor dental structure, crowded
  teeth
• Disproportionate features
• Upper extremities are shorter than lower
  extremities
• Hands are short fingers are stubby
• Average adult height is about 4 feet tall

4
A Social History of Achondroplasia

• Depicted in ancient Egyptian art
• Classical Greece and Rome
• In Renaissance and Medieval courts,
• dwarves were often owned as a sign of
  wealth
• Isabella dEste and Diego Velázquez
• Scandinavian Mythology
• 18th and 19th century Russia

5
Dwarfism in 19th and 20th Century

• P.T. Barnum and Charles Stratton
• Effects of Hollywood

6
Achondroplasia Today

• Please dont use the M word.
• Acceptable terms are Dwarf or Little Person
• Dwarf tossing is outlawed in many states
• If nurtured properly, dwarf children achieve
  success and happiness
• Us and Them focus on similarities and ways to
  even out the balance
• Simple, helpful tools include
• A step stool
• Pedal extensions in automobiles
• Tailored clothing
• Support groups such as Little Peoples
  Association

7
Interesting hereditary facts

• Nine of 10 born with achondroplasia have
  average-sized parents
• So 90 are caused by new mutation from
  average-sized parents
• Fathers 40 are more likely to have children with
  achondroplasia

• In 10, the mutation may pass from generation to
  generation
• If both parents have achondroplasia, their
  children have
• 50 chance of having achondroplasia
• 25 chance of being average size
• 25 chance of having two altered copies of the
  mutation (double-dominant or homozygous).
• Homozygous infants are stillborn or die shortly
  after birth
• Currently, there is no routine screening for
  achondroplasia
• Couples at risk (one or both parents with
  achondroplasia) may choose ultrasound and DNA
  testing for achondroplasia or double-dominant/homo
  zygous

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How does Achondroplasia affect development?

• Obstructive Upper Airway Disease
• Middle-ear infections hearing problems
• Because of large heads, short limbs and poor
  muscle tone, motor skills are delayed
• Spinal alignment problems
• Back pain
• Walking problems
• Excessive weight gain

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Treatment Options

• Growth Hormone Therapy (GHT)
• Lumbar lordosis (reverse curvature of spine)
• Lumbosacral spinal stenosis (narrow spinal canal
  adds pressure to spinal cord)
• Lumbar laminectomy surgery

• Limb lengthening surgery is very controversial
• 70 have transient pain
• 45 have infections
• 35 experience foot drop
• 30 experience stiff knees
• 15 experience stiff ankles
• Reports of incorrect alignment (legs are uneven)

10
Personal Account

• Dr. Michael Ain
• Sent out 20-30 applications to medical schools
• Attended Albany Medical College
• Pediatric Orthopedic Surgeon
• Specializes in orthopedic problems of
  dwarfismand related disorders
• Greenberg Center for Skeletal Dysplasia at Johns
  Hopkins
• Married, has 2-year-old with achondroplasia

11
References
Human Growth Foundation http//home.earthlink.ne
t/dkennedy56/dwarfism_hgfachon.html Hopkins
Medicine Greenberg Center http//www.hopkinsmedi
cine.org/greenbergcenter/achon.htm March of
Dimes http//www.marchofdimes.com/professionals/6
81_1204.asp Little People of America
(LPA) http//www.lpaonline.org/around.html Betty
Adelson, Dwarfism Medical and Psycosocial
Aspects of Profound Short Stature (Johns Hopkins
University Press, 2005) MedPage
Today http//www.medpagetoday.com/OBGYN/Pregnancy
/tb/1749 Encyclopedia Brittannica
Online http//www.britannica.com/eb/article-90316
49?querydwarfism20historyct Dwarfs Not a
Fairy Tale film documentary produced by the
Children of Difference Foundation Johns Hopkins
Magazine, April 1999, Aiming High http//www.jhu
.edu/jhumag/0499web/ortho.html