Article Title: Strategies to improve early diagnosis of Klinefelter syndrome

Authors: Alberto Ferlin

Date of Publication: October 2020

“Klinefelter syndrome is the most frequent chromosome disorder in men, but it is largely undiagnosed or receives a late diagnosis in adulthood. This condition is characterized by an extra X-chromosome: approximately 80%-90% of patients with Klinefelter syndrome have a 47,XXY karyotype, 10%-20% mosaicisms of two different genetic lines such as 47,XXY/46,XY, isochromosome X, and higher number of X chromosomes. Although our knowledge on this syndrome substantially improved in last years, the diagnostic rate is still low. It has been estimated that only 25% to 40% of subjects with 47,XXY Klinefelter syndrome are ever diagnosed. A prenatal diagnosis is made in 15–20% of these cases, 10% is diagnosed before puberty, 15% at puberty, and the remaining 50–60% of cases are diagnosed during adulthood, typically in the course of a fertility workup, with some cases diagnosed even after the age of 50 or 60 years. Variants with higher number of X chromosomes (48,XXXY and 49,XXXXY) have more severe phenotype and distinct clinical features, which leads to higher diagnostic rate than 47,XXY. This manuscript refers to the most common form 47,XXY syndrome and strategies to improve early and timely diagnosis.”

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