Two cases of microvillus inclusion disease caused by MYO5B deficiency with prenatal abnormalities

Backgrounds Microvillus inclusion disease (MVID) characterizes as intractable life‐threatening watery diarrhea malnutrition after birth. Materials & Methods Here we describe two patients with prenatal ultrasound findings of bowel dilation or increased amniotic fluid volume presented intractable diarrhea after birth. Exome sequencing and Intestinal biopsy were performed for the patients and their parents to reveal the underlying causes. The mutations were verified by Sanger sequencing and quantitative polymerase chain reaction. Results Exome sequencing revealed that both of the patients carrying MYO5B compound heterozygote mutations that were inherited from their parents. Conclusion Here we describe two cases with MVID caused by MYO5B deficiency, which was the most common caused with prenatal ultrasound findings of bowel dilation and increased amniotic fluid volume. Due to the lack of effective curative therapies, early diagnosis even in prenatal of MVID can provide parents with better genetic counseling on the fetal prognosis. Key points What's already known about this topic? Microvillus inclusion disease (MVID) is characterized by intractable life‐threatening watery diarrhea and malnutrition after birth and lacks effective treatment. What does this study add? Previous cases have reported infantile diarrhea syndrome after birth in cases of MVID. In the two cases presented here, both fetuses presented with generalized bowel dilation and increased amniotic fluid volume, which mimicked intestinal obstruction on the prenatal ultrasound. These cases expand the prenatal phenotype profile of MIVD.