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Acid alpha-glucosidase (GAA)

An enzyme responsible for the breakdown of glycogen (a large complex carbohydrate molecule) within a compartment of the cell known as the lysosome. Pompe disease is caused by an inherited deficiency or dysfunction of acid alpha-glucosidase (GAA).

Acid maltase deficiency (AMD)

Synonym of Pompe disease.

Autosomal recessive disease

Autosomal recessive diseases are genetic disorders passed from parent to child only when the child inherits two abnormal copies of a gene, one from each parent.

Bilevel positive airway pressure (BiPAP)

Bilevel positive airway pressure (BiPAP) is a modified version of the continuous positive airway pressure (CPAP). This mode offers two different levels of air pressure: increased pressure during inhalation and decreased pressure during exhalation. BiPAPs may work better for those individuals who cannot comfortably breathe out against the fixed pressure of the standard device.

Cardiac Hypertrophy

Refers to enlargement of the walls of the heart. It is usually diagnosed with echocardiogram but can also be seen in x-rays. Ventricular hypertrophy is the enlargement of ventricles (lower chambers) in the heart. In the case of Pompe disease, abnormal accumulation of glycogen in the cardiac muscle fibers leads to increase in the heart size. This is characteristic of patients with infantile onset Pompe disease, and is rarely seen in patients with late onset Pompe disease.


Enlargement of the heart.


An individual who does not display the symptoms of a disease, but carries the gene (or genes) for it. A carrier can pass the abnormal gene (or genes) to offspring.


The self-replicating genetic structures of cells that contain DNA (the molecule that encodes genetic information). Chromosomes come in pairs, and a normal human cell contains 46 chromosomes.


Existing at birth, referring to certain mental or physical traits, malformations, or diseases, which may be hereditary or due to an influence occurring during gestation (in utero).

Continuous positive airway pressure (CPAP)

CPAP ventilators provide positive pressure that is constant when a patient inhales and exhales. This can require more work for the muscles to exhale. For people with Pompe disease, the CPAP machine is generally used to treat sleep apnea (when breathing stops for short periods during sleep).

Creatine kinase (CK)

Creatine kinase (CK) is an enzyme found in muscle, brain, and other tissues. CK is released in increased quantities when muscle injury occurs.

Deoxyribonucleic acid (DNA)

The molecule that carries the genetic instructions for making living organisms. Located in the nucleus of a cell, the DNA molecule determines the structure, function and behavior of the cell.


A protein that triggers or "catalyzes" a biochemical reaction.

Exertional dyspnea

Excessive shortness of breath after exercise.

"Floppy baby" syndrome

An abnormal condition of newborns and infants where there is extremely low tone of the muscles; frequently a sign of Pompe disease in infants.


The functional and physical unit of heredity that occupies a specific location (locus) on a chromosome. Formed from DNA, genes are passed from parent to offspring and are responsible for the inherited characteristics that distinguish one individual from another.

Genetic counselor

A health care professional who has obtained training and credentials in the area of genetics and who provides information and support to families who may be at risk for inherited conditions.


A physician who specializes in genetics, the study of heredity and variation of organisms.


The genetic make-up of an individual's cells. The genotype together with the biologic environment produce the phenotype, or the visible characteristic displayed.


A large, complex carbohydrate molecule stored in the liver and muscles. Glycogen releases glucose (sugar) into the blood when needed by cells, and is the chief source of stored fuel in the body.

Glycogen storage disease

A group of inherited metabolic disorders involving the enzymes responsible for the synthesis and breakdown of glycogen. There are several types of GSDs, which are classified by a number, by the name of the defective enzyme, or by the name of the doctor who first described the condition.

Glycogen storage disease type II (GSD-II)

Synonym of Pompe disease.

Gower sign (aka Gowers maneuver)

(Commonly seen in children with muscular dystrophy as a result of extreme muscle weakness.) Gower sign refers to an abnormal method of attempting to stand up, in which the person begins with both arms and legs on the floor and then uses the arms to push against the legs and raise up the trunk to an upright posture. Sometimes described as "climbing up the legs."


Enlargement of the liver.


An individual that has one normal copy and one abnormal copy of a specific gene.


The enlargement or overgrowth of a part or organ, not due to tumor formation. Hypertrophy denotes greater bulk through increase in size, but not in number, of cells or other individual tissue elements.


A condition of diminished tone of the skeletal muscles, and the reduced resistance of muscles to passive stretching.


Exaggerated forward curvature of the lumbar and/or cervical areas of the spine.

Lysosomal storage disorder (LSD)

A group of more than 40 genetic diseases that are caused by inborn errors of metabolism and that result in the accumulation of various substances within a compartment of the cell known as the lysosome. People with LSDs are born with a deficiency or dysfunction of certain enzymes found within the lysosome. Synonym of lysosomal storage disorder.


A sac-like organelle (a structurally discrete component of a cell) that contains various digestive enzymes as well as acidic materials.


Enlargement of the tongue.


The smallest particle of a substance that retains all the properties of the substance and is composed of one or more atoms.


A permanent change in genetic material, usually in a single gene.


Any disorder or disease of muscle tissue or muscles.


A physician who diagnoses and treats disorders of the nervous system.

Neuromuscular disorder

A disorder involving the relationship between nerves and muscles, and especially the weakening or dysfunction of the muscles.


The inability to breathe easily in a flat body position.


The visible characteristics (e.g. eye color) that are produced by the interaction of the genotype (the genetic constitution of an organism) and the biologic environment.

Physical therapist

A specialist trained in the treatment of diseases and injury through exercise and physical activities.


The technique of monitoring normal and abnormal physiologic activity during sleep.

Pompe disease

A genetic disorder affecting both children and adults that is characterized by progressive muscle weakness and breathing difficulty. Pompe disease is caused by a deficiency or dysfunction of the enzyme acid alpha-glucosidase (GAA) that is responsible for the breakdown of glycogen (a large complex carbodhydrate molecule) within a compartment of the cell, resulting in an excessive accumulation of glycogen, especially in the muscles. Also known as glycogen storage disease type II (GSD-II) and acid maltase deficiency (AMD).


Any of a number of naturally occurring complex substances (such as enzymes or antibodies) involved in essential life functions.

Registered dietician

A professional who has obtained training and credentials related to the use of specialized diets to address a variety of problems.

Ribonucleic acid (RNA)

A nucleic acid that helps transfer information from DNA to the protein-forming system of the cell.


An abnormal lateral curvature of the spine.


Sleepiness; drowsiness.


A surgical operation to create an opening into the trachea (windpipe).


Relating to a vacuole, a small cavity or space containing air or fluid.

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Organizations & Websites

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