What are the other Names for this Condition? (Also known as/Synonyms)

• Dibasic Aminoaciduria 1
• Hyperdibasic Aminoaciduria 1
• Hyperdibasic Aminoaciduria Type 1

What is Dibasic Aminoaciduria Type 1? (Definition/Background Information)

• Dibasic Aminoaciduria Type 1 is a rare inherited disorder, in which there is excess excretion of dibasic amino acids, such as lysine, arginine and ornithine, by the kidneys
• These amino acids are classified as “di-amino monocarboxylic compounds”

Who gets Dibasic Aminoaciduria Type 1? (Age and Sex Distribution)

• Dibasic Aminoaciduria Type 1 is a rare congenital disorder. The disease may manifest itself as early as infancy
• The disorder has been reported in a few French-Canadian, Italian, and Turkish families
• Both males and females may be affected

What are the Risk Factors for Dibasic Aminoaciduria Type 1? (Predisposing Factors)

• A positive family history may be an important risk factor, since Dibasic Aminoaciduria Type 1 can be inherited
• Children born to parents who are close blood relatives (such as first cousins) may have a higher risk for Dibasic Aminoaciduria 1

It is important to note that having a risk factor does not mean that one will get the condition. A risk factor increases one’s chances of getting a condition compared to an individual without the risk factors. Some risk factors are more important than others.

Also, not having a risk factor does not mean that an individual will not get the condition. It is always important to discuss the effect of risk factors with your healthcare provider.

What are the Causes of Dibasic Aminoaciduria Type 1? (Etiology)

The gene mutation(s) that cause Dibasic Aminoaciduria Type 1 is currently unknown.

• It is believed that lysine, arginine, and ornithine are transported by a unique pathway, and impairment of this pathway causes Dibasic Aminoaciduria Type 1
• Based on published literature, it appear that the disorder can be inherited in an autosomal dominant or autosomal recessive manner

Autosomal dominant: Autosomal dominant conditions are traits or disorders that are present when only one copy of the mutation is inherited on a non-sex chromosome. In these types of conditions, the individual has one normal copy and one mutant copy of the gene. The abnormal gene dominates, masking the effects of the correctly function gene. If an individual has an autosomal dominant condition, the chance of passing the abnormal gene on to their offspring is 50%. Children, who do not inherit the abnormal gene, will not develop the condition or pass it on to their offspring.

Autosomal recessive: Autosomal recessive conditions are traits or disorders that occur when two copies of an abnormal gene have been inherited on a non-sex chromosome. If both parents have an autosomal recessive condition, there is a 100% likelihood of passing on the mutated genes to their children. If, however, only one mutant copy of the gene is inherited, the individual will be a carrier of the condition, but will not be present with any symptoms. Children born to two carriers, have a 25% chance of being homozygous dominant (unaffected), a 50% chance of being heterozygous (carrier), and a 25% chance of being homozygous recessive (affected).

What are the Signs and Symptoms of Dibasic Aminoaciduria Type 1?

The signs and symptoms of Dibasic Aminoaciduria Type 1 may vary in type and severity among affected individuals, with some being asymptomatic. The signs and symptoms of Dibasic Aminoaciduria Type 1 may include the following:

• Excess lysine, ornithine and arginine in the urine
• Mild malabsorption
• Excess ammonia in blood
• Mental retardation

How is Dibasic Aminoaciduria Type 1 Diagnosed?

Dibasic Aminoaciduria Type 1 is diagnosed on the basis of the following information:

• Complete physical examination
• Thorough medical history evaluation
• Assessment of signs and symptoms
• Laboratory tests to check for:
• Excess excretion of lysine, arginine and ornithine in urine
• Levels of dibasic amino acids and ammonia in blood
• Imaging studies
• Biopsy studies, if necessary

Many clinical conditions may have similar signs and symptoms. Your healthcare provider may perform additional tests to rule out other clinical conditions to arrive at a definitive diagnosis.

What are the possible Complications of Dibasic Aminoaciduria Type 1?

The complications of Dibasic Aminoaciduria Type 1 may include:

• Poor feeding and weight gain
• Intellectual disability

Complications may occur with or without treatment, and in some cases, due to treatment also.

How is Dibasic Aminoaciduria Type 1 Treated?

There is no cure for Dibasic Aminoaciduria Type 1, since it is a genetic condition. The treatment is usually given to manage the signs and symptoms (which may include supplementation of amino acids lost in urine) and any complication that may develop.

How can Dibasic Aminoaciduria Type 1 be Prevented?

• Dibasic Aminoaciduria Type 1 may not be preventable, since it is a genetic disorder.
• Genetic testing of the expecting parents (and related family members) and prenatal diagnosis (molecular testing of the fetus during pregnancy) may help in understanding the risks better during pregnancy
• If there is a family history of the condition, then genetic counseling will help assess risks, before planning for a child
• Active research is currently being performed to explore the possibilities for treatment and prevention of inherited and acquired genetic disorders
• Regular medical screening at periodic intervals with tests and physical examinations are recommended

What is the Prognosis of Dibasic Aminoaciduria Type 1? (Outcomes/Resolutions)

• The prognosis of Dibasic Aminoaciduria Type 1 is dependent upon the severity of the signs and symptoms and associated complications, if any
• Individuals with mild conditions have better prognosis than those with severe symptoms and complications
• Typically, the prognosis may be assessed on a case-by-case basis

Additional and Relevant Useful Information for Dibasic Aminoaciduria Type 1:

The following DoveMed website link is a useful resource for additional information:

http://www.dovemed.com/diseases-conditions/rare-disorders/