Renal Dysgenesis

Renal dysgenesis, comprising a diverse group of disorders that are characterized by defects in the embryonic development, includes abnormalities in the size or position of the kidney and abnormalities in renal differentiation. Renal dysplasia is defined as an abnormality in metanephric differentiation. Kidney size is variable, and normal renal tissue is often minimally present or absent. One of the syndromes associated with renal dysplasia is renal-coloboma syndrome, an autosomal dominant disorder that affects the development of the kidneys and eyes. Affected individuals present with optic disc dysplasia and renal anomalies, especially renal hypoplasia. Another syndrome is Denys-Drash syndrome, an autosomal dominant disorder that is characterized by the triad of diffuse mesangial sclerosis, male pseudohermaphroditism, and Wilms' tumor. Denys-Drash syndrome usually manifests in early infancy with proteinuria leading to nephrotic syndrome. Edema and proteinuria can present between 2 weeks and 10 months of age. Renal function declines rapidly, and most patients develop end-stage renal disease before 3 years of age. Yet another syndrome is Frasier syndrome that is an autosomal dominant disorder closely related to Denys-Drash syndrome and consists of intersex disorders and nephropathy. WT1gene mutations are associated with male pseudohermaphrodism in Denys-Drash syndrome and intersex in Frasier syndrome. Affected XY males with Frasier syndrome may appear to have a normal female phenotype including normal development of pubic hair and breast tissues. Townes-Brocks syndrome is characterized by renal anomalies (mainly hypoplastic kidneys), deformity of the external ear, deafness, imperforate anus, and limb malformations. TBS is a rare autosomal dominant disorder with an estimated frequency of 1 in 250,000 live births.