congenital lactase deficiency

Congenital lactase deficiency is a severe gastrointestinal disorder that presents in newborns, most reported in Finland. It arises from pathogenic variants in the LCT gene, which encodes the lactase enzyme responsible for digesting the sugar lactose found in milk. Affected infants typically develop symptoms soon after birth when fed breast milk or lactose-containing formulas. Although precise prevalence estimates are not available, the disorder is considered very rare, underscoring the need for early recognition and intervention.

Newborns with this condition usually experience persistent watery diarrhea shortly after feeding with milk or formulas that contain lactose. This diarrhea is a hallmark of the disorder, often leading to rapid fluid loss and potential electrolyte imbalances if not managed expeditiously. In some cases, infants may also display feeding intolerance and general irritability as a response to gastrointestinal discomfort. That not all individuals experience every symptom and that the severity of symptoms can vary considerably from one case to another.

The underlying cause of congenital lactase deficiency is attributed to mutations in the LCT gene, which plays an essential role in producing the lactase enzyme. This enzyme normally helps break down lactose into simpler sugars that can be readily absorbed, but its deficiency leads to an osmotic imbalance in the gut and subsequent watery diarrhea. The condition is inherited in an autosomal recessive manner, meaning that an affected infant has received one mutated gene from each parent. Families with this genetic pattern may benefit from genetic counseling to better understand recurrence risks and implications for future pregnancies.

Currently, management of congenital lactase deficiency focuses primarily on supportive care and dietary modifications, as there are no approved treatments specifically targeting the underlying genetic defect. The cornerstone of treatment is the avoidance of lactose, typically achieved by using lactose-free formulas to reduce gastrointestinal symptoms and prevent dehydration. Supportive measures such as maintaining proper hydration and ensuring nutritional adequacy are also critical. A multidisciplinary team approach, including pediatricians and dietitians, is recommended, and genetic counseling is advised to help families understand the condition and make informed decisions about future pregnancies.

Outcomes for individuals with congenital lactase deficiency depend largely on the promptness of diagnosis and the effectiveness of dietary management. With early intervention focused on lactose avoidance and supportive care to maintain hydration and nutrition, many affected infants are able to avoid severe complications. Although the condition requires lifelong dietary management, most individuals can achieve a good quality of life. Outcomes described in medical literature continue to evolve as standards of care improve, and the course of the disorder can vary based on symptom severity and individual response to treatment. Families are encouraged to work closely with their healthcare team and consider genetic counseling for ongoing support and planning.

There are clinical trials underway exploring new treatment approaches for congenital lactase deficiency. Although only a few studies are active at this time, ongoing research aims to enhance our understanding of the disorder and improve management strategies. Individuals interested in learning more about clinical trials are encouraged to search ClinicalTrials.gov or consult their healthcare team for further guidance.