Exploring congenital sucrase-isomaltase deficiency in autism spectrum disorder patients with irritable bowel syndrome symptoms: A prospective SI gene sequencing study.
One in every fourteen autism patients with IBS-like symptoms may actually have a treatable sugar-enzyme defect called CSID.
01Research in Context
What this study did
Doctors sequenced the SI gene in 98 autism patients who had tummy pain, diarrhea, or bloating. They wanted to see how many had congenital sucrase-isomaltase deficiency (CSID).
CSID means the body cannot break down table sugar or starch. The team used next-generation gene sequencing to find the exact mutations.
What they found
Seven out of ninety-eight kids (about 7%) carried CSID mutations. These children had looked like plain IBS cases until the gene test.
The finding suggests CSID is under-diagnosed in autism. A simple gene test can spot the real cause of gut distress.
How this fits with other research
Brown et al. (2011) showed that over half of autistic children lack lactase, the enzyme for milk sugar. Tanyel et al. now add sucrase-isomaltase defects to the list. Together, the papers map two separate sugar-enzyme problems that can both masquerade as behavior flare-ups.
Patowary et al. (2017) also used gene sequencing in autism, but hunted mitochondrial DNA instead. Their work and the new study show how targeted sequencing can uncover hidden medical causes one gene at a time.
Unlike broad genome scans such as Liu et al. (2016) and Xia et al. (2020), Tanyel zoomed in on a single gut gene and found an immediate, treatable diagnosis in a small but real slice of patients.
Why it matters
If a client has chronic diarrhea, gas, or belly pain, ask the pediatrician about SI gene testing. Fixing CSID is as simple as giving an enzyme replacement powder with meals. Behavior may improve once the gut stops hurting.
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02At a glance
03Original abstract
Congenital sucrase-isomaltase deficiency (CSID) is an inherited metabolic disorder causing chronic gastrointestinal symptoms and malnutrition when untreated. Most CSID patients are likely to remain under- or misdiagnosed. This study aimed to investigate prevalence of CSID among patients with autism spectrum disorder (ASD) presenting with irritable bowel syndrome (IBS) symptoms via prospective SI gene sequencing. A prospective cross-sectional study was conducted on 98 ASD patients exhibiting gastrointestinal symptoms consistent with IBS. Participants were assessed according to Rome IV criteria and underwent SI gene sequencing. Demographic, clinical, and dietary data were collected and analyzed. Sucrose content in various fruits and vegetables was evaluated using three-day food record, and gastrointestinal symptoms were rated on Likert scale. Seven patients (7%) were diagnosed with CSID based on SI gene analysis, revealing six different variants, including four novel mutations. One patient was homozygous for one variant, and six patients were heterozygous. Clinical presentations predominantly included diarrhea, abdominal pain, and bloating, with two patients showing growth retardation. One patient was diagnosed in adulthood. Food allergy and lactose intolerance were the misdiagnoses prior to CSID diagnosis in two patients. Real prevalence of CSID is likely underestimated. Clinical heterogeneity and non-specific symptoms contribute to diagnostic challenges. Gastrointestinal symptoms consistent with IBS in ASD patients should include CSID in differential diagnosis. Early genetic screening for SI variants in ASD patients with IBS symptoms can facilitate timely diagnosis and management, improving outcomes. Heterozygous variants of the SI gene should also be considered, as heterozygous patients can exhibit typical CSID symptoms.
Autism research : official journal of the International Society for Autism Research, 2025 · doi:10.1002/aur.3293