Pediatric Patient Resources

Top Contributors - Alicia Dupilka 

Original Editors - Alicia Dupilka, Elaine Lonnemann, Kim Jackson, Leana Louw, WikiSysop, Admin and Scott Buxton

Resources for Physiotherapists and the Families of their Pediatric Clients

Down Syndrome 

Definition: Genetic disorder occurring when the individual has full or a partial copy of chromosome 21. This extra genetic material causes an alteration in the development of the child.

How common is it?
     • Most common genetic disorder
     • ~1:691 babies are born each year with Down’s Syndrome
     • ~6,000 babies are born each year with Down’s Syndrome

Types

     • Trisomy 21 (Nondisjunction)
          o The pair of the 21st chromosome fails to separate
          o Extra chromosome is replicated in every cell in the body
          o Accounts for ~95% of cases

     • Mosaicism
          o Nondisjunction takes place in chromosome 21 in one cell but not all cells
          o Accounts for ~1% of cases
          o May have fewer characteristics than other types of Down’s Syndrome

     • Translocation
          o Part of chromosome 21 breaks off during cell division and attaches to another chromosome, typically chromosome 14
          o Accounts for ~4% of cases

Causes

     • Cause of nondisjunction is currently unknown
          o Research suggests the likelihood increases as women age
          o No definitive research suggesting environmental factors of the parents before or during pregnancy

How is Down’s Syndrome Diagnosed?

     • Prenatally

          o Screening tests
                Most only provide a probability
                Blood test: measures quantities of various substances in the mother’s blood
                Ultrasound: checks for “markers”

          o Diagnostic tests
                Can provide a definite diagnosis with almost 100% accuracy
                Carry up to a 1% risk of causing a spontaneous termination
                Chorionic villus sampling (CVS): usually performed in first trimester between 9 and 11 weeks
                Amniocentesis: usually performed in the second trimester after 15 weeks

     • At birth

          o Usually identified by certain physical traits
                Low muscle tone
                Single deep crease across the palm of the hand
                Slightly flattened facial profile
                Upward slant to the eyes

          o Chromosomal analysis may also need to be done to confirm the diagnosis
                This is done by drawing a sample of the baby’s blood