Background: The ichthyosis is a hereditary skin disease and inherited by autosomal dominant, autosomal recessive and X recessive trait separately. The X-linked ichthyosis (XLI) is the most frequent cutaneous disease and general incidence accounts for one in 2000-5000 male births. Molecular pathogenesis of XLI is due to mutations, which are large deletion, missense, frame shift and nonsense in STS gene. The vast majority of mutation frequency is a large deletion, which are found in 85-90% of patients with XLI. An exon deletion of the STS can be detected by Polymerase chain reaction with exon specific primers. An identification of STS gene mutation has various importance such as 1) detection of mutation type; 2) for genetic counselling, 3) disease severity, 4) carrier detection. Methods: In the present study, pedigree analysis was used for type of inheritance, and Polymerase chain reaction was used to detect a deletion in STS gene and normal control used. A deletion was identified in case PCR bands were not visualized in agarose gels. Results: We included one patient, who had typical symptoms of XLI including dark, adherent scales on skin. Mutation analysis of the STS gene showed that the patient had whole gene deletion (del: Exon 1-10), which was demonstrated by the repeated amplification failure of exons. We used a sample of healthy man as a wild type control, which showed normal amplification of STS gene’s exons. Further, the current study will be focused on the screening of heterozygote large deletion of Del: Exon1-10 of STS gene among patient’s female relatives. Conclusion An ichthyosis case enrolled in this study was inherited by X-recessive and we identified whole exon deletion of STS gene in this patient.

Backround Peutz–Jeghers (PJ) syndrome is a rare autosomal dominant disorder characterized by a mucocutaneous pigmentationon on oral mucosa and multiple hamartomatous polyps located in the digestive tract except esophagus. PJ syndrome can be diagnosed in early childhood by a characteristic pigmentation and family history of polyposis. However, it is often diagnosed first as a polyp in the small intestine that causes obstruction and intussusception and is often treated with a bowel resection. If diagnosed in young childhood, an effective non-invasive method is to resect the polyps by tying off the blood supply to the polyps, that is the method named ischemic polypectomy, before they grow to the point of obstruction using a endoscopy. PJ syndrome is rare in Mongolia, but in severe cases, small intestine polyps are treated only surgically. Double-balloon-endoscopy (DBE) has been performed at the Mongolian- Japanese Hospital since 2023, making it possible to diagnose and treat the syndrome endoscopically. Our patient, a 15-year-old boy, had a mucocutaneous pigmentation that had been previously undiagnosed and was first diagnosed with intussusception at the age of 13. He had undergone 4 endoscopic procedures for upper and lower gastrointestinal polyps at the National Center for Maternal and Child Health successfully. In our hospital, we found endoscopically multiple hamartomatous polyps of various sizes between 1-3 cm, and a 3 mm diameter tumor that filled 3/4 of the intestinal lumen was treated by ischemic polypectomy. After the procedure, there were no early or late complications related to the procedure. The child's condition improved, the main complaints subsided, and he continues his daily life normally. However, follow-up DBE is required.