https://www.selleckchem.com/products/jr-ab2-011.html Congenital diarrheal disorders are heterogeneous conditions characterized by diarrhea with onset in the first years of life. They range from simple temporary conditions, such as cow's milk protein intolerance to irreversible complications, such as microvillous inclusion disease with significant morbidity and mortality. Advances in genomic medicine have improved our understanding of these disorders, leading to an ever-increasing list of identified causative genes. The diagnostic approach to these conditions consists of establishing the presence of diarrhea by detailed review of the history, followed by characterizing the composition of the diarrhea, the response to fasting, and with further specialized testing. Severe combined immunodeficiency (SCID) encompasses a group of genetic defects. T cell development is universally affected and has alteration of B and/or NK cells. We present the case of a 5-day-old boy with combined heterozygous frame shift (c.256_257del, p.(Lys86Valfs*33)) and missense (c.1186C>T, p.(Arg396Cys)) variations in the RAG1 gene. He was admitted to our institution because of 0 TREC on Newborn Screen and worsening rash. Initially thought to have Omenn syndrome versus maternal engraftment with graft versus host disease, DNA analysis identified the noted mutations and he subsequently received a bone marrow transplant from a matched sibling. Numerous disorders present with vesiculopustular eruptions in the neonatal period, ranging from benign to life-threatening. Accurate and prompt diagnosis is imperative to avoid unnecessary testing and treatment for benign eruptions, while allowing for adequate treatment of potentially fatal disorders. In this review, we highlight several rare blistering diseases of the newborn. A diagnostic approach is outlined to provide clinicians with a framework for approaching a neonate with vesicles, pustules, or ulcers. Autoinflammatory disorders are rare genetic defects