SGBS is characterized by large and small postnatal growth, facial dysmorphism, and multiple skeletal and visceral events. A third of the patients have a heart defect that leads to a high mortality rate in newborns due to stimulus conduction.
The infants are already larger at birth than the average, whereafter they continue to grow at an above-average growth rate. The other symptoms are very different in history and expression, leading to large differences in prognosis. While some patients die prematurely, others reach adulthood. The facial dysmorphisms include widely spaced eyes, an abnormally large mouth, a large tongue, a broad nasal root, and a cleft palate. However, not all symptoms are always present.
Other symptoms affect the abdomen and the abdomen. Some patients have more than two nipples. They have an unusual opening in the muscle covering the abdomen, as well as umbilical and inguinal hernias. There is a risk that the abdomen and internal organs will move towards the chest, which will negatively affect the development of the lungs and heart.
The manifestation occurs prenatally or in the neonatal period and follows an X-linked recessive inheritance. The cause is a mutation in the GPC3 gene in the chromosome region Xq26, which codes for Glyician-3. This is mainly located in tissues of mesodermal origin and influences its signal chains. A few cases have no GPC3 mutation, which concludes genetic heterogeneity.