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

• Adenosine Monophosphate Deaminase Deficiency Disorder
• AMPD1 Deficiency Disorder
• Myopathy due to Myoadenylate Deaminase Deficiency Disorder

What is Adenosine Monophosphate Deaminase 1 Deficiency Disorder? (Definition/Background Information)

• Adenosine Monophosphate Deaminase 1 (AMPD1) Deficiency Disorder is an inherited condition that can affect the muscles used for movement (skeletal muscles). Many people with AMPD1 Deficiency Disorder do not have symptoms
• People who do have symptoms typically have muscle pain (myalgia), cramping, and weakness after exercise, and often get tired faster than others. Some affected people appear to have more severe symptoms
• AMPD1 Deficiency Disorder is caused by changes (mutations) in the AMPD1 gene and is inherited in an autosomal recessive manner
• Other types of AMPD deficiency include the acquired type (due to a muscle or joint condition), and the coincidental inherited type (due to both mutations in the AMPD1 gene and a separate muscle or joint disorder)

(Source: Adenosine Monophosphate Deaminase 1 Deficiency Disorder; Genetic and Rare Diseases Information Center (GARD) of National Center for Advancing Translational Sciences (NCATS), USA.)

Who gets Adenosine Monophosphate Deaminase 1 Deficiency Disorder? (Age and Sex Distribution)

• Adenosine Monophosphate Deaminase 1 Deficiency Disorder is a rare congenital disorder. The presentation of symptoms may occur following the birth of the child
• Both males and females may be affected
• Worldwide, individuals of all racial and ethnic groups may be affected

What are the Risk Factors for Adenosine Monophosphate Deaminase 1 Deficiency Disorder? (Predisposing Factors)

• A positive family history may be an important risk factor, since Adenosine Monophosphate Deaminase 1 Deficiency Disorder can be inherited
• Currently, no other risk factors have been clearly identified for AMPD1 Deficiency Disorder

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 Adenosine Monophosphate Deaminase 1 Deficiency Disorder? (Etiology)

Adenosine Monophosphate Deaminase 1 (AMPD1) Deficiency Disorder is caused by changes (mutations) in the AMPD1 gene.

• This gene gives the body instructions to make an enzyme called AMP deaminase, which plays a role in producing energy in skeletal muscle cells
• Mutations in the AMPD1 gene disrupt the function of AMP deaminase, which impairs the ability of muscle cells to make energy. This lack of energy can lead to the muscle problems associated with AMPD1 deficiency
• Other types of AMPD deficiency are known as the acquired type (due to a different muscle or joint condition), and the coincidental inherited type (due to both mutations in the AMPD1 gene and a separate muscle or joint disorder)
• This condition is inherited in an autosomal recessive manner, which means that both copies of the responsible gene in each cell must have changes (mutations) for a person to be affected. The parents of a person with an autosomal recessive condition each carry one copy of the mutated gene and are referred to as carriers
• There are many people who have mutations in both copies of the gene responsible for AMPD1 deficiency, but do not have any signs or symptoms (are unaffected).  The reasons for this are unclear

(Source: Adenosine Monophosphate Deaminase 1 Deficiency Disorder; Genetic and Rare Diseases Information Center (GARD) of National Center for Advancing Translational Sciences (NCATS), USA.)

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 Adenosine Monophosphate Deaminase 1 Deficiency Disorder?

The signs and symptoms of Adenosine Monophosphate Deaminase 1 Deficiency Disorder may include:

Very frequently present symptoms in 80-99% of the cases:

• Exercise-induced muscle fatigue
• Exercise-induced myalgia
• Limb muscle weakness
• Muscle cramps

Occasionally present symptoms in 5-29% of the cases:

• Generalized hypotonia
• Rhabdomyolysis
• Increased muscle fatigability

Many people with AMPD1 Deficiency Disorder do not have symptoms.

(Source: Adenosine Monophosphate Deaminase 1 Deficiency Disorder; Genetic and Rare Diseases Information Center (GARD) of National Center for Advancing Translational Sciences (NCATS), USA.)

How is Adenosine Monophosphate Deaminase 1 Deficiency Disorder Diagnosed?

Adenosine Monophosphate Deaminase 1 Deficiency Disorder is diagnosed on the basis of the following information:

• Complete physical examination
• Thorough medical history evaluation
• Assessment of signs and symptoms
• Laboratory tests
• 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 Adenosine Monophosphate Deaminase 1 Deficiency Disorder?

The complications of Adenosine Monophosphate Deaminase 1 Deficiency Disorder may include:

• Severe muscle weakness
• Unable to walk, immobility

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

How is Adenosine Monophosphate Deaminase 1 Deficiency Disorder Treated?

Although there is no cure for Adenosine Monophosphate Deaminase 1 Deficiency Disorder, there may be ways to manage symptoms.

• One possibility is the use of a sugar called D-ribose. This sugar is easily absorbed in digestive system and rapidly cleared by metabolic pathways
• It may provide an additional source of energy for muscle; however, the helpful effects of D-ribose are short-term

(Source: Adenosine Monophosphate Deaminase 1 Deficiency Disorder; Genetic and Rare Diseases Information Center (GARD) of National Center for Advancing Translational Sciences (NCATS), USA.)

How can Adenosine Monophosphate Deaminase 1 Deficiency Disorder be Prevented?

Currently, Adenosine Monophosphate Deaminase 1 Deficiency Disorder 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 Adenosine Monophosphate Deaminase 1 Deficiency Disorder? (Outcomes/Resolutions)

People with Adenosine Monophosphate Deaminase 1 Deficiency Disorder may first develop symptoms during childhood, adolescence, or as young or older adults. Many people do not have any symptoms.

• Those with symptoms typically have only rapid fatigue, cramps or muscle pain (myalgia) after exercising
• In some cases, symptoms may progress over the first few years, but then the condition usually stabilizes (does not get worse)
• In many people, it is not progressive at all. There are no known consistent complications of the condition
• There is no evidence of muscular dystrophy or muscular wasting in affected people, and it does not affect smooth muscle or other organs (only skeletal muscle)
• Life expectancy is not shortened

(Source: Adenosine Monophosphate Deaminase 1 Deficiency Disorder; Genetic and Rare Diseases Information Center (GARD) of National Center for Advancing Translational Sciences (NCATS), USA.)

Additional and Relevant Useful Information for Adenosine Monophosphate Deaminase 1 Deficiency Disorder:

Adenosine Monophosphate Deaminase 1 Deficiency Disorder is also known by the following names:

• AMP Deaminase 1 Deficiency Disorder
• AMP Deaminase Deficiency Disorder
• MMDD Disorder
• Myoadenylate Deaminase Deficiency Disorder

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

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