Molecular Cytogenetics in the Diagnostics of Balanced Chromosome Mutations in the Pig (Sus scrofa) – A Review

Continually improved cytogenetic techniques (differential staining and high resolution banding techniques), complemented with the molecular genetics methods (FISH and PRINS), enable chromosomal mutations to be accurately identified in the karyotype of the pig (Sus scrofa). The major breeding problem are balanced mutations because of their hidden nature, as they affect the animals with normal body conformation (and normal semen parameters in boars), which transfer these aberrations to the next generations and disseminate in the population. This refers to the structural rearrangements (translocations and inversions), causing developmental abnormalities and considerably reducing fertility and productivity parameters in breeding herds, which results in substantial financial losses. Routine karyotype screening using modern cytomolecular diagnostic methods is necessary due to the potential emergence of new mutations and the rapid spread of these genetic defects in the population, especially under artificial insemination conditions.

Trisomía parcial 9p derivada de una translocación recíproca 9;15, materna. Reporte de casos

Objectives: to highlight the importance of performing karyotype in children with congenital malformations in order to have a confirmatory diagnosis, in parents to exclude the possibility of being carriers of chromosomal abnormalities and perform the genetic counseling. Clinical cases description: Female patient with 3 years and 2 months old to whom karyotype was performed by global neurodevelopmental delay and microcephaly, and her mother with 34 years old without any clinical manifestations, to both patients, lymphocyte culture and chromosomal analysis with a High Resolution Banding techniques GTG and C were performed. The mother’s karyotype was 46,XX,t(9;15)(q10;q10)(p10;p10),add14p. The father’s karyotype was normal, 46,XY, and the girl’s karyotype resulted in a pure Trisomy 9p: 47,XX,+del(9)(q11). Discussion: This chromosomal rearrangement in mother included a nonhomologous reciprocal translocation between the long arms of pair chromosomes 9 and 15 and between the short arms of the same chromosomes, additional to it, an unknown origin material was also observed in short arm from one chromosome of the 14 pair. In meiosis of this type of rearrangement, the father’s normal homologous chromosomes are paired with the mother’s translocated chromosomes and as a result of 3:1 segregation a gamete with one chromosome else was originated that after fertilization resulted in an unbalanced translocation confirming the pure trisomy in the patient.