Genetics project Fall 2010
A genetic disorder is a disease that is caused by an abnormality in an individual's DNA. Abnormalities can range from a small mutation in a single gene to the addition or subtraction of an entire chromosome or set of chromosomes. To learn more about different genetic disorders, browse through the Genetic Disorder Library.
genetic disorders
Tuesday, November 16, 2010
Monday, November 15, 2010
lyush nyan syndrom questions
Wednesday, November 10, 2010
What is the Lyush Nyan Syndrome?
What is Lesch-Nyhan syndrome?
Lesch-Nyhan syndrome is a condition characterized by the overproduction and accumulation of uric acid, a waste product of normal chemical processes that is found in blood and urine. The overproduction of uric acid can cause gouty arthritis (arthritis caused by an accumulation of uric acid in the joints), kidney stones, and bladder stones. Problems with the nervous system and behavioral disturbances are also characteristic of this disorder. Abnormal involuntary muscle movements such as flexing, jerking, and flailing are often displayed by people affected with this disorder. People with Lesch-Nyhan syndrome usually cannot walk, require assistance sitting, and are generally wheelchair-bound. Self-injury, including biting and head banging, is the most common and distinctive behavioral problem in those with Lesch-Nyhan syndrome.
How common is Lesch-Nyhan syndrome?
The prevalence of Lesch-Nyhan syndrome is approximately 1 in 380,000 individuals. This condition occurs with a similar frequency in all populations.
Molecular Genetics
This condition is inherited in an X-linked recessive pattern. The gene associated with this condition is located on the X chromosome, which is one of the two sex chromosomes. In males (who have only one X chromosome), one altered copy of the gene in each cell is sufficient to cause the condition. In females (who have two X chromosomes), a mutation would have to occur in both copies of the gene to cause the disorder. Because it is unlikely that females will have two altered copies of this gene, males are affected by X-linked recessive disorders much more frequently than females. A striking characteristic of X-linked inheritance is that fathers cannot pass X-linked traits to their sons.
Causes
It mostly occurs in boys. Persons with this syndrome are missing or are severely lacking an enzyme called hypoxanthine guanine phosphoribosyltransferase 1 (HGP). The body needs this enzyme to recycle purines. Without it, abnormally high levels of uric acid build up in the body.The condition affects about 1 in 380,000 people.
Treatment
No specific treatment exists for Lesch-Nyhan syndrome. The gout medication, allopurinol, successfully decreases uric acid levels, but does not improve the neurological outcome.
Some symptoms may be relieved with the drugs carbidopa/levodopa, diazepam, phenobarbital, or haloperidol.
Symptoms
The excess uric acid levels cause children to develop gout-like swelling in some of their joints. In some cases, kidney and bladder stones develop because of the high uric acid levels.
Males with Lesch-Nyhan have delayed motor development followed by bizarre, sinuous movements and increased deep tendon reflexes. A striking feature of Lesch-Nyhan syndrome is self-destructive behavior characterized by chewing off fingertips and lips, if not restrained. It is unknown how the enzyme deficiency causes these problems.
Reference
http://www.nlm.nih.gov/medlineplus/ency/article/001655.htm
http://www.nationwidechildrens.org/lesch-nyhan-syndrome
http://www.nationwidechildrens.org/lesch-nyhan-syndrome
What is Blue rubber bleb nevus syndrome?
Blue rubber bleb nevus syndrome (BRBNS) is a syndrome characterized by multiple cutaneous venous
malformations in association with visceral lesions, most commonly affecting the GI tract. In 1860, Gascoyen first described an association between cavernous hemangiomas of the skin and similar lesions in the GI tract. In 1958, Bean further described these lesions and coined the term blue rubber bleb nevus syndrome.
Blue rubber bleb nevus syndrome is an important syndrome because of its potential for serious or fatal bleeding.
Note the image below.
Treatment
No systemic therapy is currently considered a standard of care for blue rubber bleb nevus syndrome (BRBNS).. One report of blue rubber bleb nevus syndrome indicated the successful use of interferon-beta to treat the manifestations of disseminated intravascular coagulation in one patient with disseminated skin and GI venous malformations.
What are the symptoms of the Blue Rubber Bleb Nevus Syndrome?
Most lesions are asymptomatic but some may be spontaneously painful or tender to palpation. Patients may note increased sweating on the skin overlying the lesion. Physical complaints or symptoms vary depending on the organ system involved Patients may report fatigue from occult blood loss. Hematemesis, melena or frank rectal bleeding may prompt emergent presentations. When bone is involved, there may be complaints of joint pain or impaired ambulation. Extracutaneous lesions also may result in epistaxis, hemoptysis, hematuria, or menorrhagia. Patients may present with blindness due to cerebral or cerebellar cavernomas that may hemorrhage into the occipital lobes.
References
malformations in association with visceral lesions, most commonly affecting the GI tract. In 1860, Gascoyen first described an association between cavernous hemangiomas of the skin and similar lesions in the GI tract. In 1958, Bean further described these lesions and coined the term blue rubber bleb nevus syndrome.
Blue rubber bleb nevus syndrome is an important syndrome because of its potential for serious or fatal bleeding.
Note the image below.
Frequency
International
Blue rubber bleb nevus syndrome (BRBNS) is a rare disorder with only approximately 150 cases reported in the world's literature. Most cases are sporadic, but autosomal dominant inheritance has been reported.
Cause
The causes of this syndrome are unknown. Not more than a few hundred cases have been described worldwide.
Sex
Blue rubber bleb nevus syndrome (BRBNS) affects males and females equally..
No systemic therapy is currently considered a standard of care for blue rubber bleb nevus syndrome (BRBNS).. One report of blue rubber bleb nevus syndrome indicated the successful use of interferon-beta to treat the manifestations of disseminated intravascular coagulation in one patient with disseminated skin and GI venous malformations.
What are the symptoms of the Blue Rubber Bleb Nevus Syndrome?
Most lesions are asymptomatic but some may be spontaneously painful or tender to palpation. Patients may note increased sweating on the skin overlying the lesion. Physical complaints or symptoms vary depending on the organ system involved Patients may report fatigue from occult blood loss. Hematemesis, melena or frank rectal bleeding may prompt emergent presentations. When bone is involved, there may be complaints of joint pain or impaired ambulation. Extracutaneous lesions also may result in epistaxis, hemoptysis, hematuria, or menorrhagia. Patients may present with blindness due to cerebral or cerebellar cavernomas that may hemorrhage into the occipital lobes.
http://emedicine.medscape.com/article/1082839-overview
http://pediatrics.aappublications.org/cgi/content/abstract/107/2/418
http://www.birthmarks.us/BRBNS.htm
http://pediatrics.aappublications.org/cgi/content/abstract/107/2/418
http://www.birthmarks.us/BRBNS.htm
Monday, November 1, 2010
Blue Rubber Bleb Nevus Syndrome
questions
Age
blue rubber bleb nevus syndrome (BRBNS) are often apparent at birth or manifest in early childhood, but late onset, beyond midlife, has been reported. GI involvement usually becomes evident during early adulthood.
Race
Blue rubber bleb nevus syndrome (BRBNS) has been reported in persons of all races,2 although whites appear to be most frequently affected.
Frequency
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