Tetrasomy 9p, a Prenatal Challenge: Two Novel Cases

Abstract

Tetrasomy 9p is a chromosomal disorder characterized by the presence of a supernumerary chromosome. This rare abnormality exhibits a broad phenotypic variability and is not clearly distinguishable from other more frequent aneuploidies in the prenatal setting. We present two prenatal cases with dissimilar phenotypes, one with solely increased fetal nuchal translucency and one with multiple congenital anomalies, and discuss prior studies. These cases illustrate the difficulty of prenatally diagnosing this condition based on phenotypic information alone. We conclude that invasive prenatal diagnosis with (molecular) karyotyping is the best choice for the prenatal detection of tetrasomy 9p.

Cases of tetrasomy 9p and trisomy 9p in prenatal diagnosis—Analysis of noninvasive and invasive test results

“…Podolsky et al presented one case with the absence of nasal bone as a marker of tetrasomy 9p ( Podolsky et al, 2011 ). Zaghi et al described one case with tetrasomy 9p and absent nasal bone ( Zaghi et al, 2022 ). Khattabi et al presented a case with tetrasomy 9p and absent nasal bone diagnosed in the first trimester ( Khattabi et al, 2015 ).…”