What happens if you lack maltase?

November 25, 2025 •

4 min read

According to the Muscular Dystrophy Association, Pompe disease, a severe form of acid maltase deficiency, is a rare genetic disorder that results in profound muscle weakness. This article explores what happens if you lack maltase, detailing the symptoms, causes, and consequences of this enzyme deficiency.

Quick Summary

A deficiency in the digestive enzyme maltase can lead to carbohydrate malabsorption and cause significant gastrointestinal issues. More severely, a lack of acid maltase results in Pompe disease, a genetic condition causing damaging glycogen accumulation in muscles.

Key Points

Maltase's function is to break down maltose, a disaccharide from starch, into glucose for energy absorption.
Intestinal maltase deficiency is linked to Congenital Sucrase-Isomaltase Deficiency (CSID), leading to digestive issues like bloating, gas, and chronic diarrhea.
Acid maltase deficiency is a genetic disorder called Pompe disease, causing a buildup of glycogen within the body's cells.
Pompe disease primarily affects the heart and skeletal muscles, leading to progressive weakness and potential respiratory or cardiac failure.
Symptoms of Pompe disease vary by age of onset, from severe hypotonia and cardiomegaly in infants to slower-progressing muscle weakness and respiratory problems in adults.
Treatment for Pompe disease involves enzyme replacement therapy (ERT), which has significantly improved the outlook for many patients.
Intestinal maltase deficiency is managed through dietary restrictions and sometimes sucrase-specific enzyme supplements, but these do not address maltose digestion.

Understanding the Role of Maltase

Maltase is a crucial digestive enzyme that plays a key role in carbohydrate metabolism. Produced primarily by the cells lining the small intestine, its main function is to catalyze the hydrolysis of the disaccharide maltose into two simple glucose molecules. This is the final and essential step in breaking down starches, which are first partially digested into maltose by amylase enzymes from the salivary glands and pancreas. The resulting glucose is then absorbed into the bloodstream to provide the body with energy. In essence, without functional maltase, the body cannot efficiently convert starches into usable fuel.

The Two Primary Forms of Maltase Deficiency

The term "maltase deficiency" can refer to two distinct conditions with very different outcomes and severity, based on the type of maltase affected.

Intestinal Maltase Deficiency

This form involves a lack of the maltase enzymes in the intestinal brush border. It is most commonly associated with Congenital Sucrase-Isomaltase Deficiency (CSID), a genetic disorder affecting multiple disaccharidases, including maltase.

Symptoms typically arise in infancy or early childhood when starchy foods are introduced into the diet.
These symptoms primarily relate to the digestive system and are caused by undigested carbohydrates fermenting in the colon.
The severity of intestinal symptoms can vary depending on the amount of residual enzyme activity.

Acid Maltase Deficiency (Pompe Disease)

This is a far more serious, rare, and progressive genetic disorder known as Pompe disease, or Glycogen Storage Disease Type II. It is caused by a mutation in the GAA gene, which leads to a deficiency of the lysosomal enzyme acid alpha-glucosidase (acid maltase). This enzyme's role is to break down glycogen within cellular lysosomes. Without it, glycogen accumulates inside the lysosomes, causing them to swell and rupture, damaging cells and tissues—especially the heart and skeletal muscles.

Gastrointestinal Symptoms of Maltase Deficiency

For individuals with intestinal maltase deficiency (often linked to CSID), a lack of the enzyme prevents the proper digestion of starches and complex carbohydrates. This leads to a number of unpleasant gastrointestinal issues, including:

Chronic, watery diarrhea: Unabsorbed maltose draws water into the colon, causing osmotic diarrhea.
Abdominal bloating and gas: Colonic bacteria ferment the undigested carbohydrates, producing gas.
Stomach pain and cramps: The fermentation process can cause significant abdominal discomfort.
Failure to thrive: In infants and young children, nutrient malabsorption can lead to poor weight gain and growth.
Severe diaper rash: The acidic nature of the diarrhea can cause irritation.

Systemic Consequences of Acid Maltase Deficiency (Pompe Disease)

In contrast to the digestive symptoms of intestinal maltase deficiency, Pompe disease manifests as a progressive myopathy due to widespread cellular damage from glycogen accumulation. The symptoms vary significantly depending on the age of onset and are often severe.

Infantile-Onset Pompe Disease

Typically manifests within the first few months of life.
Characterized by profound generalized muscle weakness (hypotonia), often referred to as "floppy infant syndrome".
Severe heart enlargement (cardiomegaly) is a common and life-threatening symptom.
Breathing problems and respiratory infections due to weakening respiratory muscles are frequent.
Without treatment, most infants do not survive past their first year due to cardiorespiratory failure.

Late-Onset Pompe Disease

Appears later in childhood or adulthood, with slower progression.
Primary symptom is progressive weakness of the skeletal muscles, especially in the hips, shoulders, and legs.
Respiratory insufficiency is a major complication as the diaphragm and other breathing muscles weaken.
Can lead to increased risk of respiratory infections, scoliosis, and mobility issues.
Cardiac involvement is less common than in the infantile form.

Comparison: Infantile vs. Late-Onset Pompe Disease


Feature	Infantile-Onset Pompe Disease	Late-Onset Pompe Disease
Age of Onset	Within the first few months of life.	After infancy, can be childhood or adulthood.
Progression	Rapid and severe progression.	Slower and more variable progression.
Cardiac Involvement	Severe heart enlargement (cardiomegaly) is common.	Typically minimal to no cardiac involvement.
Muscle Weakness	Profound generalized hypotonia and weakness.	Progressive weakness, particularly in proximal limb and respiratory muscles.
Life Expectancy	Significantly shortened; often fatal within the first year without treatment.	Shortened due to respiratory issues, but longer than infantile form.
Primary Complication	Cardiorespiratory failure.	Respiratory failure and loss of mobility.

Management and Treatment Options

For both forms of maltase deficiency, management involves different approaches. For intestinal deficiencies (CSID), the focus is on dietary management and potential enzyme supplementation. For Pompe disease, the treatment is more complex and involves enzyme replacement therapy (ERT).

Intestinal Maltase Deficiency Management

Dietary modification: A diet with reduced or restricted sucrose and starch intake is the main treatment. However, adherence can be challenging.
Sucrase replacement therapy: An oral solution containing sucrase (like Sacrosidase) can be effective for sucrose digestion but does not address maltase or starch breakdown.
Dietitian support: Regular consultation with a specialized dietitian is recommended to ensure adequate nutrition.

Acid Maltase Deficiency (Pompe Disease) Treatment

Enzyme Replacement Therapy (ERT): Infusions of recombinant human acid alpha-glucosidase (alglucosidase alfa, brand names Myozyme and Lumizyme) can replace the missing enzyme. It has shown significant success in reversing cardiac damage in the infantile form and improving outcomes for late-onset disease.
Respiratory Support: For patients with advanced respiratory muscle weakness, mechanical ventilation may be necessary.
Nutritional Support: High-protein or branched-chain amino acid-supplemented diets have shown potential benefits for some adults with late-onset disease.
Supportive Care: Physical therapy is important to manage muscle weakness and improve motor function.

Conclusion

What happens if you lack maltase depends significantly on which type of maltase is deficient. An intestinal maltase deficiency, often linked to CSID, causes uncomfortable but manageable gastrointestinal distress. In contrast, a deficiency of the lysosomal acid maltase, known as Pompe disease, is a serious, progressive genetic disorder leading to debilitating muscle weakness and potentially life-threatening cardiac and respiratory complications. While dietary management and medication can help with intestinal issues, enzyme replacement therapy is a transformative treatment for Pompe disease. Patients and families should work closely with healthcare professionals to get an accurate diagnosis and develop a comprehensive management plan. The Muscular Dystrophy Association offers valuable resources for individuals affected by Pompe disease.

Frequently Asked Questions

Intestinal maltase deficiency involves a lack of the enzyme that digests carbohydrates in the small intestine, leading to digestive issues. Acid maltase deficiency, known as Pompe disease, is a genetic disorder that causes a glycogen buildup in cellular lysosomes, damaging muscles and organs, especially the heart and respiratory system.

For intestinal maltase deficiency (CSID), symptoms appear when infants are introduced to solid foods or formulas containing starch, causing watery diarrhea, abdominal bloating, and poor weight gain (failure to thrive). For infantile Pompe disease, symptoms include generalized muscle weakness (hypotonia) and an enlarged heart.

While genetic maltase deficiencies like Pompe disease are inherited, late-onset forms can manifest in adulthood. Intestinal issues can sometimes be triggered or worsened by other gastrointestinal conditions that damage the intestinal lining, such as gastroenteritis.

Intestinal maltase deficiency is typically diagnosed by assessing enzyme activity from a small bowel biopsy. For acid maltase deficiency (Pompe disease), diagnosis involves enzyme assays (measuring GAA activity in blood or tissue) and genetic testing to confirm mutations in the GAA gene.

Yes, treatment depends on the type. Intestinal deficiencies are managed with dietary restrictions and potentially sucrose-specific enzyme supplements, though starch remains an issue. Pompe disease is treated with enzyme replacement therapy (ERT), which has greatly improved patient outcomes.

For intestinal maltase deficiency (CSID), foods high in starch and sucrose should be restricted. This includes starchy vegetables, baked goods, and added sugars like table sugar, honey, and maple syrup. A specialized dietitian can provide a comprehensive list and plan.

Untreated infantile Pompe disease is typically fatal, with most babies succumbing to cardiorespiratory failure within the first two years of life. For late-onset Pompe disease, untreated symptoms lead to progressive muscle weakness, mobility loss, and eventual respiratory failure.