Lesser Known Disorders
Each issue of this series contains at least three lesser known disorders. Some of these disorders may contain subtypes which will also be presented. You will also notice that each disorder has a code. These codes represent the coding system for all disabilities and disorders listed in the Educator’s Diagnostic Manual(EDM) Wiley Publications.
Disorders in this issue:
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Osteogenesis imperfecta (OI)-Brittle Bone Disease
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Multiplex Developmental Disorder
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Addison’s Disease
OI 1.05 – Osteogenesis imperfecta (OI)-Brittle Bone Disease
Disability Category – Orthopedic Impairment
Definition
Osteogenesis imperfecta (OI) is a genetic disorder characterized by bones that break easily, often from little or no apparent cause. There are at least four recognized forms of the disorder, representing a range of severities. For example, a person may have just a few or as many as several hundred fractures in a lifetime (National Institute of Arthritis and Musculoskeletal and Skin Diseases, 2004).
Explanation
This inherent weakness of the bones is due to a malfunction in the body’s production of the protein collagen. Collagen, of which there are at least ten identifiable subtypes, is found in the connective tissues of the body and make up a large portion of the bones and cartilage. It is the substance that holds the tissues together, providing strength and mass to the bones. For a person with OI, either the amount of collagen being produced is too little, or the quality being produced is poor. Either way, the bones of a person with OI are less dense and break easily. It is estimated that OI affects between 20,000 and 50,000 people in the United States (Cleveland Clinic, 2004).
At least four types of OI have been identified:
OI 1.05a Type I Osteogenesis imperfecta
Type I is the most common form of OI. People with this type of the disease tend to fracture easily and exhibit other features, such as blue sclera, hearing loss, a triangular face, spinal curvature, and dental problems.
OI 1.05b Type II Osteogenesis imperfecta
Type II, though less common, is a very severe form of the disease. Newborns with Type II often fracture before birth and usually die shortly after birth.
OI 1.05c Type III Osteogenesis imperfecta
Individuals with Type III OI tend to be very small in stature, experience hearing loss at a young age, and have a barrel-shaped rib cage.
OI 1.05d Type IV Osteogenesis imperfecta
Type IV OI individuals tend to fracture easily and often have spinal curvature and significant dental problems.
OI 1.06 Osteopetrosis
Definition
Generalized hereditary condition consisting of excessive bone mineralization, resulting in altered stature, frequent fractures, lack of bone marrow hematopoietic function (A hematopoietic stem cell is a cell isolated from the blood or bone marrow that can renew itself, can differentiate to a variety of specialized cells, can mobilize out of the bone marrow into circulating blood, and can undergo programmed cell death, called apoptosis—a process by which cells that are detrimental or unneeded self-destruct), and a tendency for severe osteomyelitis (an acute or chronic bone infection, usually caused by bacteria) of the jaws (Marquette University School of Dentistry, 2001).
Explanation
Osteopetrosis is a congenital disease characterized in each of its forms by defective osteoclast function. Osteoclasts are the cells responsible for bone resorption. They are necessary for the formation of bone marrow. In people with osteopetrosis, osteoclasts do not function normally and the cavity for bone marrow does not form. This causes bones that appear dense on x-ray and cannot resist average stressors and therefore break easily. The condition is quite rare; incidences have been reported at 1 in 20,000–500,000 for the dominant form and 1 in 200,000 for the recessive.
Symptoms include:
- Pain
- Frequent fractures, especially of the long bones, which often do not heal
- Nerve compression, leading to headache, blindness, deafness
- Enlarged spleen
- Osteomyelitis
- Frontal bossing of the skull
- Unusual dentition, including malformed and unerrupted teeth
- Infection
- Bleeding
- Stroke (Osteopetrosis.org, 2002)
There are three major types of osteopetrosis:
OI 1.06a Adult Form
A milder type of osteopetrosis that is found in adults between 20 and 40 years old. This form rarely causes a significant reduction in life expectancy.
OI 1.06b Intermediate Form
A type of osteopetrosis that is less severe than the malignant infantile form. Found in children younger than 10 years old, it is more severe than the adult form of osteopetrosis, but usually does not shorten life expectancy.
OI 1.06c Malignant Infantile Form
A type of osteopetrosis that is very severe. It is inherited when both parents have an abnormal gene that is passed to the child. The disease is apparent from birth and frequently ends in death. Despite its name, the disease is not related to cancer.
MR 1.06-Multiplex Developmental Disorder
Disability Category-Autism
Definition
Turner Multiplex Complex (Multiplex) Developmental Disorder (MCDD) is a proposed developmental disorder (or syndrome) designed to encompass preschool and early school age children who have consistent and enduring deficits in affect regulation, relatedness, and thought. Such children are thought to represent another variant in the spectrum of pervasive developmental disorders (Demb & Noskin, 2001).
Diagnostic Symptoms
Unknown MDD symptoms emerge in earliest childhood, often in the first years of life, and persist throughout development. Diagnostic criteria for MDD include (Yale Developmental Disabilities Clinic, 2005):
1. Impaired social behavior/sensitivity, similar to that seen in autism, such as:
- Detachment, avoidance of others, or withdrawal
- Impaired peer relations
- Highly ambivalent attachments
- Limited capacity for empathy or understanding what others are thinking or feeling
2. Affective symptoms, including:
- Intense, inappropriate anxiety
- Recurrent panic
- Emotional lability, without obvious cause
3. Thought disorder symptoms, such as:
- Sudden, irrational intrusions on normal thoughts
- Magical thinking
- Confusion between reality and fantasy
- Delusions such as paranoid thoughts or fantasies of special powers
Further KeyPoints
There are some children who display the severe, early-appearing social and communicative deficits characteristic of autism who also display some of the emotional instability and disordered thought processes that resemble schizophrenic symptoms. Cohen et al. (1986) coined the term Multiplex Developmental Disorder (MDD) to describe these children, although they are often given a diagnosis of PDD-NOS by clinicians who may be unfamiliar with this terminology (Yale Developmental Disabilities Clinic, 200
OHI 14.02 Addison’s Disease
Disability Category – Other Health Impaired
Definition
Addison’s disease is a disorder that results in one’s body producing insufficient amounts of certain important hormones (Mayo Clinic, 2005a). Addison’s disease is an endocrine or hormonal disorder that occurs in all age groups and afflicts men and women equally. The disease is characterized by weight loss, muscle weakness, fatigue, low blood pressure, and sometimes darkening of the skin in both exposed and nonexposed parts of the body.
Addison’s disease occurs when the adrenal glands do not produce enough of the hormone cortisol and, in some cases, the hormone aldosterone. The disease is also called adrenal insufficiency, or hypocortisolism (Endocrine and Metabolic Diseases Information Service, 2004).
Explanation
Because the symptoms progress slowly, they are usually ignored until a stressful event like an illness or an accident causes them to become worse. This is called an addisonian crisis, or acute adrenal insufficiency. In most cases, symptoms are severe enough that patients seek medical treatment before a crisis occurs. However, in about 25 percent of patients, symptoms first appear during an addisonian crisis. The symptoms of adrenal insufficiency usually begin gradually. Characteristics of the disease are:
- chronic, worsening fatigue
- diarrhea
- loss of appetite
- low blood pressure that falls further when standing, causing dizziness or fainting
- muscle weakness
- nausea
- skin changes
- vomiting
- weight loss (Endocrine and Metabolic Diseases Information Service, 2004).
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