X-linked polyendocrine adenopathy, enteropathy with immune dysregulation syndrome (IPEX), is a rare genetic disorder of the immune system caused by mutations in the human FOXP3 gene. In the 2009 primary immune-deficiency disease (PID) classification, it is classified as an autoimmune syndrome within the broad category of immune regulatory imbalance diseases. What is X-linked inheritance? Sex linkage refers to the phenomenon that certain traits controlled by genes on the X chromosome are always inherited along with sex, also known as sex-linked inheritance. (a) X-linked dominant inheritance The gene controlling a trait is located on the X chromosome and is dominant. (b) X-linked recessive inheritance The gene controlling a trait on the X chromosome is a recessive gene. The X-linked recessive inheritance can be summarized as follows: 1) Most of the patients with the disease are male; 2) The children of male patients are normal, with significant discontinuity between generations; 3) The daughters of male patients are phenotypically normal, but may be carriers of the disease-causing gene and may produce grandsons who are diseased. 4. One-half of the female patient’s sons are carriers of the disease-causing gene and one-half are patients; one-half of the daughters are normal and one-half are carriers of the disease-causing gene, and there is a possibility of having diseased persons in the third generation. In this case, the patient is a female carrier, the husband is normal, and the genetic profile is shown below: How is the disease diagnosed and treated? In infants, the clinical finding of early onset intractable diarrhea, multiple endocrinopathies, autoimmune phenomena and a clinical phenotype of growth retardation should alert them to the disease. Flow cytometry is important as a rapid test in the diagnosis of this disease, and the final diagnosis depends on gene sequence analysis. Infants born without formal treatment usually die within 2 years of age, and for long-term survival, allogeneic HSCT is currently the ultimate option. In women of childbearing age, if the patient presents with recurrent miscarriages and intrauterine death, and the sex of the fetus is male on chromosomal examination, or if the infant is born with early-onset insulin-dependent diabetes mellitus, intractable diarrhea and unknown renal damage, IPEX should be considered as a possibility, and the patient’s mother and fetus should be examined by flow cytometry for CD4+CD25+FOXP3+ regulatory T-cell ratio and FOXP3 protein expression. PGS technique for IVF can be performed in patients with a history of recurrent miscarriage and intrauterine fetal death, after the diagnosis of the disease is confirmed. Therefore, in the literature, this patient underwent PGS for sex-selective transfer in 2012 and delivered a female baby in May 2013.