Horseshoe kidney and a rare TSC2 variant in two unrelated individuals with tuberous sclerosis complex.

Tuberous sclerosis complex (TSC) is an autosomal dominant multisystem disorder characterized by abnormalities involving the skin, brain, kidney (angiomyolipomas, cysts), and heart. Horseshoe kidney has not been considered to be a common renal manifestation of TSC but it has been previously reported in two patients with TSC. We report on two unrelated females with typical manifestations of TSC, horseshoe kidney, and an identical variant c.5138G>A in exon 39 (p.Arg1713His) of TSC2 gene. These cases provide evidence that horseshoe kidney is associated with TSC and add to the evidence for the pathogenicity of this variant. Furthermore, one of the patients also had a diaphragmatic hernia which has been reported twice in the medical literature in individuals with TSC. It is possible that a diaphragmatic hernia is another rare manifestation of TSC and that TSC should be included in the differential diagnosis of infants with a diaphragmatic hernia. Given that both a horseshoe kidney and a diaphragmatic hernia are findings that can be detected prenatally on an ultrasound examination, our findings may have implications for prenatal genetic counseling.