Chromosome 9 Inversion: Pathogenic or Benign? A Comprehensive Systematic Review of all Clinical Reports

Abstract

Background: Inversion of chromosome 9 (inv[9]) is known as one of the most common structural balanced chromosomal variations. Chromosome 9 is highly susceptible to structural rearrangements, specifically to pericentric inversions. Various investigators have posited that inv(9) with different breakpoints could be the cause of several abnormal conditions in individuals, whereas others have considered it a benign variant. To our knowledge, a consensus regarding the effects of this inversion has yet to emerge. Objective: This study aims to discuss the pathogenic/benign effects of inv(9) in all possible clinical conditions detected in the occurrence of this abnormality. Methods: Studies on inv(9) were collected via PubMed, MalaCards, Google Scholar, and NORD, along with the search terms of inv(9), pericentric inv(9), and chromosome 9 variants. Additionally, the incidence of inv(9) and the karyotype and clinical findings of individuals reported with this variant were investigated. Results: The collection of the studies reviewed shows that inv(9) is associated with various conditions such as congenital anomalies, growth retardation, infertility, recurrent pregnancy loss, and cancer. The clinical features associated with this variant in humans vary between growth stages. Further, there have been no shared clinical findings in a specific period. Conclusions: Although there is no conclusive evidence for the pathogenicity of this rearrangement, prenatal genetic counseling on inv(9) and further clinical and molecular studies would be helpful in chromosome 9-related problems.

Cytogenetic Investigation of Infertile Patients in Hungary: A 10-Year Retrospective Study

“…These results suggest that the inv(9) may be a benign chromosomal variant and does not show association with reproductive failure. As there is no conclusive evidence for the pathogenicity of this rearrangement, further clinical and molecular studies would be helpful to clarify the role of inv(9) in infertility [ 38 ].…”

Exploring the impact of pericentric inversion of chromosome 9 on fertility in sperm donors

“…All these studies disproved the inter-chromosomal effect on the inv(9) variant. Notably, although the above studies, including the present study, focused on two karyotypes, inv(9)(p11q13) and inv(9)(p12q13), these karyotypes represented the majority of inv(9) variants 22 ( e.g ., 92.9% in the present study). In addition, the inv(9)(p13q12) and inv(9)(p13q13) inversion fragments are similar in size to inv(9)(p11q13)/inv(9)(p12q13).…”

“…The incidence of the inv(9) variant varies across geographic and ethnic groups. 22 To minimize the influence of these factors and more accurately evaluate the incidence of this variant in men, we selected seven studies conducted in China 11 12 14 23 24 25 26 for comparison. All these studies were conducted on infertile populations ( Table 2 ).…”

Chromosome 9 aberrations diagnosed at a pediatric hospital in Tabasco, Mexico

“…Rivera y colaboradores 10 , han señalado que la inversión del cromosoma 9 es una alteración estructuralmente frecuente en la población general y en pacientes con defectos al nacimiento, siendo las inversiones pericéntrica más frecuentes las inv(9) (p11q13) y la inv(9) (p12q13), así mismo, Liang S, y colaboradores 11 , y Mohsen-Pour N, y colaboradores 12 sostienen que las inversiones que afectan a la región pericentromérica del cromosoma 9 tienen puntos de interrupción localizados en 9q12 o 9q13-21,1 y con menos frecuencia en 9q12 3 .señalan marcada preferencia de ocurrencia en el sexo femenino de la inversión pericéntrica, y en el sexo masculino de la heterocromatina aumentada en el brazo largo del cromosoma 9 (9qh+).…”