Table 6 - Estimates of heterozygosis
and homozygosis in the population studied
ERCC1 located on chromosome segment 19q13.2- 3 usually showed a frequent loss of heterozygosis
in NSCLC, and its expression showed different response to gemcitabine chemohterapy.
In fact, pairing in meiosis constitutes the main problem in inversion heterozygosis
. An odd number of crossover events (during the pachytene stage of meiosis I) within the inversion segment can lead to two monocentric recombinants with reciprocal duplications/ deficiencies in the gametes, ending up in a risk of inheriting such an imbalance when conception occurs.
The authors discussed this high degree of polymorphism in such a small sample and population of a seemingly relict species, and considered a number of possibilities, one of which was that heterozygosis
for segments was maintained because they were adaptive (White & Nickerson 1951).
After analyzing DNA samples from the 300 participants, the polymorphism was identified in four apparently healthy adult volunteers -all in heterozygosis
. The first case was a 21-year-old male who was born from non-consanguineous parents, another two individuals were identified as carriers of the polymorphism; they are the parents of a family who presented two cases of sudden infant death after two consecutive pregnancies and they are cousins.
After sequencing all the 18 exons, including the intron-exon boundaries and the promoter, four LDLR mutations were detected in heterozygosis
: one nonsense mutation (p.C146X) in exon 4 and three missense mutations, one in exon 3 (p.R57H) and two in exon 17 (p.V806F and p.W789L).
In contrast, the other study carried out with a population from the Zapotitlan Valley of central Mexico, using only three microsatellite loci (Ramirez-Padilla, 2008), found an observed heterozygosis
of 0.67 and an excess of heterozygotes as endogamy coefficient showed (FIS = -0.028).
Genetic diversity may increase yield ascribed to heterosis in at least two ways: More genetic diversity may increase the hybrid's area of adaptedness over a larger geographic area, and it may increase heterozygosis
because diverse geographic areas favor different traits thus different genetic loci are affected.
It was also at BARC that Wright first proposed the variable he designated as F to express an inbreeding coefficient, the mathematical correlation that measures the decrease in heterozygosis
from that in the foundation stock.
In addition, even if chromosomal rearrangements are involved in hybrid sterility, this may result from heterozygosis
for multiple rearrangements that individually are not underdominant.
The presence of the G allele was found to be associated with aggressive behavior and social problems, and aggressive behavior was found to be associated with heterozygosis
The parents used in the crosses presented a considerable degree of heterozygosis
, because the plants were selected at orchards originating from seedlings grown from seeds, and studies conducted by Pessanha et al.