Introduction
An uncommon inherited metabolic condition known as a sucrase-isomaltase (SI) deficiency is characterized by a shortage or lack of the enzymes sucrase and isomaltase. This enzyme complex (sucrase-isomaltase) helps break down certain sugars, such as sucrose, and some starch digestion byproducts (dextrins). The minute, finger-like projections (microvilli or brush border) along the small intestine host the sucrase-isomaltase enzyme complex. Nutrients based on ingested sugar and starch cannot be adequately absorbed from the gut when this enzyme complex is lacking. The other names for this condition are
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Congenital sucrase isomaltase deficiency (CSID).
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Congenital sucrase-isomaltase malabsorption.
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SI deficiency.
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Congenital sucrose intolerance.
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Disaccharide intolerance I.
What Are the Causes of Sucrase-Isomaltase Deficiency?
Mutations in the SI gene bring on congenital sucrase-isomaltase deficiency. Chromosome 3 has been identified as the defective gene (3q25-q26). The enzyme sucrase-isomaltase is produced according to instructions from the SI gene. This enzyme in the small intestine converts sucrose and maltose into their basic sugar forms. The small intestine then absorbs these simple carbohydrates. This disorder is brought on by mutations that change how sucrase-isomaltase is produced, functions, or is structurally altered. Constipation is a symptom of congenital sucrase-isomaltase deficiency and is brought on by abnormalities that inhibit the enzyme from metabolizing sucrose and maltose.
What Is the Inheritance Pattern of Sucrase-Isomaltase Deficiency?
Sucrase isomaltase deficiency is inherited in an autosomal recessive pattern. Human cells contain chromosomes, which house the genetic material that makes each person unique. 46 chromosomes typically make up human body cells. The sex chromosomes are X and Y, and human chromosomal pairs are numbered from 1 to 22. In contrast to males, who have one X and one Y chromosome, females have two X chromosomes. The short arm of each chromosome is denoted "p," and the long arm is designated "q." Chromosomes are further separated into numerous numbered bands. For instance, "chromosome 3q25-q26" refers to the area on the long arm of chromosome 3 that lies between bands 25 and 26. Each chromosome contains hundreds of genes, and the numbered bands identify their locations.
What Determines the Inheritance Pattern of the Congenital Illness?
The status of a gene's two copies—one received from the mother and one from the father—determines the majority of hereditary illnesses. Recessive genetic diseases result when a person receives two copies of an atypical gene for the same trait, one from each parent. A person will be a carrier for the disease but will not exhibit any symptoms if they inherit one normal gene and one disease gene. With each pregnancy, there is a 25 percent chance that two carrier parents will pass the mutated gene, resulting in an afflicted child. With each pregnancy, there is a 50 percent chance that the child will carry the same gene as one of the parents. A child has a 25 percent chance of inheriting normal genes from both parents. Both men and women are at the same level of danger.
Heterozygous Inheritance - Some parents of children with CSID may have some sucrase-isomaltase absorption issues but not the other signs of the condition. The sucrase-isomaltase gene in these parents is considered heterozygous for a faulty form. A person with two distinct genes - one from each parent - for a given trait is considered heterozygous. A heterozygous individual for a genetic disorder brought on by a dominant gene will be impacted. On the other hand, a heterozygous person for a genetic condition caused by a recessive gene will typically not develop the disease or only experience a milder form of it.
What Are the Symptoms of Sucrase-Isomaltase Deficiency?
Infants affected have symptoms quickly after consuming sucrose, which is present in fruits, starches, and modified milk formulae. Possible symptoms are:
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Abdominal swelling (distension).
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Explosive, watery diarrhea causing abnormally low body fluid levels (dehydration).
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Abdominal discomfort.
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Malnutrition from inadequate absorption of vital nutrients.
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Failure to thrive due to a delay in growth.
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Increase in weight.
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Abrasion and irritation (excoriation) of the skin on the buttocks due to protracted diarrhea episodes.
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Vomiting.
The symptoms of this condition differ from person to person. Babies and young children typically experience more severe symptoms than adults. For example, an infant with CSID may not exhibit symptoms while breastfed or using a lactose-only formula. Still, symptoms may appear as soon as sucrose is added to the diet through fruit juices, solid meals, medications, and other sources. Starch intolerance may disappear during the first few months or years of life.
In contrast, sucrose intolerance - which causes the majority of the disorder's symptoms - often gets better as the child gets older, showing only intermittent or mild symptoms as they get older. In certain circumstances, symptoms might not become apparent until the start of puberty. Because younger people's diets frequently include a higher carbohydrate consumption, symptoms in newborns and early children are typically more severe than those in affected adults. Additionally, newborns and young toddlers require less time for intestinal processing.
How Is Sucrase-Isomaltase Deficiency Diagnosed?
Any newborn experiencing severe watery diarrhea after consuming milk-modified or glucose-polymer formula should be suspected of having CSID. Clinical evaluation, distinctive symptoms, a thorough patient history, and specialist testing may all be used to confirm the diagnosis of this illness. For instance,
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Blood Serum Tests- Blood serum tests of an affected person may show a flat serum glucose curve after deliberate feeding of defined quantities of sucrose, isomaltose, or its equivalent, palatinose, for tolerance testing purposes.
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Blood and Urine Samples - These may show the presence of the disaccharides sucrose, isomaltose, or palatinose.
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Monosaccharides in Feces - Sucrose, glucose, and fructose, and an acidic pH level of less than five or six may be present in the feces.
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Enzyme Tests (Assays) - Assess the intestine's sucrase-isomaltase activity. This treatment often entails taking a tiny tissue sample (biopsy) from one or more locations within the small intestine.
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Sucrose Hydrogen Breath Test - Detects an abnormally high quantity of hydrogen in a person who has consumed sucrose.
How Is Sucrase-Isomaltase Deficiency Treated?
The standard treatments used for sucrase-isomaltase deficiency are
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Dietary Management- Dietary management with a low-sugar or sucrose-free diet is the mainstay of CSID treatment. A low-starch or starch-free diet is also suggested in some circumstances, particularly during the first few years of life. While many affected people may display a lifelong intolerance to sucrose, some may show evidence of sucrose tolerance within their second decade of life.
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Fresh Baker’s Yeast- Fresh Baker’s Yeast which has sucrase activity, may be consumed by those with this disease following sugar consumption. The yeast should be consumed on a full stomach, as the diluting effects of gastric secretions significantly enhance sucrase activity.
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Enzyme Replacement Therapy - The FDA (Food and Drug Administration) has authorized the orphan sacrosidase oral solution (Sucraid) to treat congenital sucrose isomaltose malabsorption. Using baker's yeast and glycerin to produce the enzyme sucrase (sacrosidase), this oral solution is an enzyme replacement therapy. Many of the symptoms connected with sucrose consumption by people with this illness have been reported to be relieved with sucraid.
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Genetic Counseling - It is advised that afflicted individuals and their families seek genetic counseling.
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Supportive and Symptomatic Treatment - For instance, it may be necessary to replenish fluids and electrolytes following episodes of diarrhea to prevent dehydration and other related symptoms.
Conclusion:
It can take some time to find the correct CSID treatment because its symptoms are sometimes mistaken for those of IBS (irritable bowel syndrome), intestinal infections, parasites, etc. However, physicians can determine if someone has CSID by procedures, including gastrointestinal endoscopic tests and breath tests. Although CSID cannot be cured, it can be treated with enzyme replacement treatment using the oral solution sucraid (sacrosidase) and an elimination diet that forbids the consumption of foods high in sugar and starch.
