Uncovering a new SASH1 mutation associated with Generalized Lentiginosis and unilateral renal dysplasia: pedigree survey and literature review

A 19-year-old female patient exhibits widespread pigmentation patches and unilateral renal dysplasia, while other systems were unremarkable. The diagnosis was generalized lentiginosis and the right kidney is dysplastic and nonfunctional. Genetic screening unveiled two heterozygous missense alterations in the SASH1 gene: c.1029C > T(p.Thr343=) and c.1566C > A(p.Ser522Arg). Her parents, while carrying the c.1029C > T(p.Thr343=) mutation, have no similar lentiginous phenotype. According to the analysis of relevant literature, both mutation sites are unprecedented in medical literature, with the c.1566C > A(p.Ser522Arg) variation representing a novel occurrence within this lineage. This finding not only contributes to the expansion of the human gene mutation repository but also furnishes critical insights for the genetic counseling of the patient and her relatives. During these consultations, elucidating the characteristics and implications of these mutations is paramount for accurately gauging the patient's risk factors and informing future familial health decisions.