Birth Defects

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Birth Defects
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What is a birth defect?

• A birth defect is an abnormality of structure,
  function or metabolism (body chemistry) present
  at birth that results in physical or mental
  disabilities or death. .

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Categories of Birth Defects

• Single-gene defects
• A mutation (change) in a single gene can cause
  birth defects. Every human being has about 20,000
  to 25,000 genes that determine traits like eye
  and hair color (4). Genes also direct the growth,
  development and functioning of every system in
  the body. Genes are packaged into each of the 46
  chromosomes inside our cells.
• Examples include
• Achondroplasia (a form of dwarfism)
• Marfan syndrome (a connective-tissue diseas
• Tay-Sachs disease (a fatal nervous system
  disorder)
• Cystic fibrosis (a serious disorder of lungs and
  other organs, affecting mainly caucasians)
• Hemophilia (a blood-clotting disorder)
• Duchenne muscular dystrophy (progressive muscle
  weakness)

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Categories of Birth Defects

• Chromosomal birth defects
• Abnormalities in the number or structure of
  chromosomes can cause many birth defects.
  Chromosomal abnormalities usually are caused by
  an error that occurred when an egg or sperm cell
  was developing. Because of the error, a baby can
  be born with too many or too few chromosomes, or
  with one or more chromosomes that are broken or
  rearranged.
• Examples include
• Down syndrome (an extra copy of chromosome 21 or
  other rearrangements resulting in extra genetic
  material from this chromosome) Affected children
  have varying degrees of intellectual
  disabilities, characteristic facial features and,
  often, heart defects and other problems.
• Trisomies 18 and 13 (an extra copy of chromosome
  18 or 13) Affected babies have multiple birth
  defects and often die in the first months of
  life.
• Sex chromosome abnormalities (missing or extra
  copies of the sex chromosomes, X and Y) These
  disorders affect sexual development and may cause
  infertility, growth abnormalities and behavioral
  and learning problems. However, most affected
  individuals live fairly normal lives. Examples
  include Turner syndrome (in which a girl is
  missing all or part of an X chromosome) and
  Klinefelter syndrome (in which a boy has one or
  more extra X chromosomes).

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Categories of Birth Defects

• Multifactorial birth defects
• Some birth defects appear to be caused by a
  combination of genes and environmental exposures.
  This is called multifactorial inheritance. In
  some cases, an individual may inherit one or more
  genes that make him more likely to have a birth
  defect if he is exposed to certain environmental
  substances, such as cigarette smoke. These
  individuals have a genetic predisposition to a
  birth defect. But if the individual is not
  exposed to the environmental substance before
  birth, he probably wont have the birth defect.
• Examples of multi-factorial birth defects
  include
• Cleft lip/palate (opening in the lip and/or roof
  of the mouth)
• Neural tube defects (NTDs) (serious birth defects
  of the brain and spinal cord, including spina
  bifida and anencephaly)
• Heart defects

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Most Common

• Heart defects
• As many as 1 in 100 babies in the United States
  are born with heart defects each year (1). While
  advances in surgery have dramatically improved
  the outlook for affected babies, heart defects
  remain the leading cause of birth defect-related
  infant deaths (8).
• Cleft lip/palate
• About 1 in 700 babies is born with cleft
  lip/palate each year (1). Affected babies can
  have problems with eating, speech and language.
  Some have a small cleft that can be corrected
  with one surgical procedure, while others have
  severe clefts and need multiple surgeries.

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• Cleft lip/palate

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Most Common

• Down syndrome
• This chromosomal abnormality affects about 1 in
  800 babies in the United States (1). Early
  intervention programs and treatment of associated
  health problems have greatly improved the outlook
  for affected individuals.
• Spina bifida (open spine)
• This disorder affects about 1 in 2,500 babies in
  the United States each year (1). Affected babies
  have varying degrees of paralysis and bladder and
  bowel problems.

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• Down Syndrome

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• Spina Bifida

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Most Common

• Other common birth defects include
  musculoskeletal defects (including arm and leg
  defects), gastrointestinal defects (including
  defects of the esophagus, stomach and intestines)
  and eye defects. These birth defects usually are
  multi-factorial.

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