Developmental Disabilities

What are developmental disabilities? 

Developmental disabilities are birth defects related to a problem with how a body part or body system works.  They may also be known as functional birth defects.  Many of these conditions affect multiple body parts or systems. 

What are the different types of developmental disabilities? 

Nervous system disabilities
These are birth defects that affect  the functioning of the  brain, spinal cord, and nervous system, which can impact intelligence and learning. These conditions can also  cause problems such as behavioral disorders, speech or language difficulties, convulsions, and movement disorders.  Some of the common nervous system disabilities include: 

• Mental retardation  - The term  mental retardation describes a certain range of scores on an IQ (intelligence quotient) test. Mental retardation can result from a number of different conditions,  including (but not limited to): 

1. Down syndrome - a set of mental  and physical characteristics related to having an extra copy of Chromosome 21. 
2. Fragile  X syndrome- the most common inherited form of mental retardation caused by a defect in a specific part of the Fragile X Mental Retardation-1 gene that causes the body to produce low amounts or none of a certain protein.  Without the protein, the brain doesn’t develop normally. 

• Autism Spectrum Disorders -  a range of problems that can affect a person's communication skills, social skills,  and intelligence. Because  autism is diagnosed on a spectrum, people with this condition can have mild symptoms or severe symptoms; but they all have a type of autism. 

Sensory-related disabilities  Sensory-related  problems are often a key part of complex birth defect patterns. For instance: 

• Children with congenital rubella are likely to be deaf, and to develop cataracts of the eyes. 
• Children with Williams syndrome have trouble seeing spatial relationships between objects around them. 
• Those with Fragile X syndrome are often very sensitive to loud noises; they may overreact or have outbursts in reaction to  such sounds. 

Metabolic Disorders 

This group of functional birth defects affects a person's metabolism,  which is the way the  body builds up, breaks down, and otherwise  processes the materials it needs to function. For example, how your body breaks down sugar to create energy is a metabolic process. Two commonly known metabolic disorders include: 

• Phenylketonuria (PKU) - a condition in which a problem with a specific enzyme, a protein that speeds up certain chemical reactions, causes mental retardation. 
• Hypothyroidism - a hormonal condition that, if left untreated in an infant, can cause mental retardation. 

Degenerative Disorders 

Some infants born with degenerative  disorders appear normal at birth, but then lose abilities or functions due to the in condition. In these cases, the defect is usually not detected until an older age,  when the child or person starts to show signs of loss of function. Some degenerative disorders  are the result of metabolic disorders.
Degenerative disorders  can cause physical, mental,  and sensory problems, depending on the specific defect. Rett syndrome is an example of a degenerative birth defect. This disorder, which usually affects girls, is most often caused by a specific genetic abnormality. 

What are the treatments for developmental disabilities? 

Many  developmental disabilities have no cure, but there are often ways to  treat the symptoms.  For example: 

• Children with Down syndrome can often benefit from  speech therapy, occupational therapy, and exercises for gross and fine motor skills. They  might also be helped by special  education and attention at school.  Surgery  can also help correct heart defects. 
• People with Fragile X syndrome can get help  to reduce or eliminate some  of the learning, physical, social and emotional, speech and language, and sensory problems common  in Fragile X. The sooner those  with Fragile X get help, the more they can learn  and the better their outcomes. 
• There are a variety  of treatment options  to help  with the symptoms of autism spectrum disorders.  This may include behavioral, occupational, physical,  and speech-language therapy.  In addition, educational specialists can help guide  the child’s school experiences. 
• Girls  with Rett syndrome can be treated  for some  of the problems associated with the condition. These treatments generally aim to slow the loss  of abilities, improve  or preserve movement,  and encourage communication  and social contact. Treatments may include help from physical therapists, occupational therapists,  and speech-language therapists.  Other options, such as medication or surgery  are also effective  for treating some  of the symptoms  of Rett syndrome. 
• Treatment for hypothyroidism, or underactive thyroid, includes daily oral hormone treatment.   
• The most effective treatment for PKU is a special diet that carefully limits  the protein phenylalanine (Phe).  People  with PKU who  are on this diet  from birth  or shortly thereafter develop normally  and usually have no symptoms of PKU. 

Where can I get more information on  developmental disabilities? 

• Facts about Down syndrome 
• Autism Overview: What We Know 
• Families and Fragile X Syndrome 
• Rett Syndrome 

Notes: Dr. M. Kristine Schlossberg

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EditText of this page (last edited March 3, 2010)