The case of a 4-year-two-month-old female patient is presented, who consulted for a special phenotype: psychomotor retardation, short stature, microcephaly, large and low-set ears, small forehead, prominent brow ridges, labial commissure open, ocular hypertelorism, short neck, mammary hypertelorism and pectus excavatum. The objective of this study is to analyze a patient with unusual phenotypic traits, through physical examination, comparative analysis with other cases, and genetic studies. The cytogenetic study revealed a mosaic karyotype, mos 46,XX,r(15)(q26.3)/46,XX with the presence of the ring in 83%. The genetic mapping array study identified the loss of 3.5 Mb in 15q26.3. Among the genes lost in the terminal region of 15q, an interaction between their protein products was evidenced according to the STRING analysis. This is the second case of a ring chromosome 15 reported in Ecuador. And it would be the 101st in the world since 1966. The special phenotype of these individuals is related to the amount of genetic material lost. The genes involved in the formation of the ring, as well as the proteins that determine these genes and the relationships in different cellular pathways, are analyzed in silico in order to understand the pathophysiology of this disorder. Its diagnosis is mostly postnatal, so the clinical approach differs individually according to the symptoms and signs that appear.