Paternal bias in parental origin ofHRASmutations in Costello syndrome

Abstract A Robertsonian translocation results in a metacentric chromosome produced by the fusion of two acrocentric chromosomes. Rb heterozygous mice frequently generate aneuploid gametes and embryos, providing a good model for studying meiotic nondisjunction. We intercrossed mice heterozygous for a (7.18) Robertsonian translocation and performed molecular genotyping of 1812 embryos from 364 litters with known parental origin, strain, and age. Nondisjunction events were scored and factors influencing the frequency of nondisjunction involving chromosomes 7 and 18 were examined. We concluded the following: The frequency of nondisjunction among 1784 embryos (3568 meioses) was 15.9%.Nondisjunction events were distributed nonrandomly among progeny. This was inferred from the distribution of the frequency of trisomics and uniparental disomics (UPDs) among all litters.There was no evidence to show an effect of maternal or paternal age on the frequency of nondisjunction.Strain background did not play an appreciable role in nondisjunction frequency.The frequency of nondisjunction for chromosome 18 was significantly higher than that for chromosome 7 in males.The frequency of nondisjunction for chromosome 7 was significantly higher in females than in males. These results show that molecular genotyping provides a valuable tool for understanding factors influencing meiotic nondisjunction in mammals.

Download Full-text

The Evolution of Genomic Imprinting

Genetics ◽

10.1093/genetics/144.3.1283 ◽

1996 ◽

Vol 144 (3) ◽

pp. 1283-1295 ◽

Cited By ~ 4

Author(s):

Atsushi Mochizuki ◽

Yasuhiko Takeda ◽

Yoh Iwasa

Keyword(s):

Growth Factor ◽

Genomic Imprinting ◽

Parental Origin ◽

Coding Region ◽

Placental Development ◽

Genetic Conflict ◽

Multiple Partners ◽

Zygotic Gene ◽

Mammalian Genes ◽

Maternal Resources

Abstract In some mammalian genes, the paternally and maternally derived alleles are expressed differently: this phenomenon is called genomic imprinting. Here we study the evolution of imprinting using multivariate quantitative genetic models to examine the feasibility of the genetic conflict hypothesis. This hypothesis explains the observed imprinting patterns as an evolutionary outcome of the conflict between the paternal and maternal alleles. We consider the expression of a zygotic gene, which codes for an embryonic growth factor affecting the amount of maternal resources obtained through the placenta. We assume that the gene produces the growth factor in two different amounts depending on its parental origin. We show that genomic imprinting evolves easily if females have some probability of multiple partners. This is in conflict with the observation that not all genes controlling placental development are imprinted and that imprinting in some genes is not conserved between mice and humans. We show however that deleterious mutations in the coding region of the gene create selection against imprinting.

Download Full-text

Distribution of diandric and digynic triploidy depending on gestational age

Journal of Assisted Reproduction and Genetics ◽

10.1007/s10815-021-02202-4 ◽

2021 ◽

Author(s):

Diana Massalska ◽

Katarzyna Ozdarska ◽

Tomasz Roszkowski ◽

Julia Bijok ◽

Anna Kucińska-Chahwan ◽

...

Keyword(s):

Gestational Age ◽

Pregnancy Loss ◽

First Trimester ◽

Parental Origin ◽

Second Trimester ◽

Chain Reaction ◽

Spontaneous Pregnancy ◽

First Trimester Of Pregnancy ◽

Polymerase Chain ◽

Fluorescent Polymerase Chain Reaction

Abstract Purpose To establish the distribution of diandric and digynic triploidy depending on gestational age. Methods 107 triploid samples tested prospectively in a single genetic department during a four-year period were analyzed for parental origin of triploidy by Quantitative Fluorescent Polymerase Chain Reaction (QF-PCR) (n=95) with the use of matching parental samples or by MS-MLPA (n=12), when parental samples were unavailable. Tested pregnancies were divided into three subgroups with regard to the gestational age at spontaneous pregnancy loss: <11 gestational weeks, 11–14 gestational weeks, and >14 gestational weeks. Results Diandric triploidy constituted overall 44.9% (46.5% in samples miscarried <11 gestational weeks, 64.3% in samples miscarried between 11 and 14 gestational weeks, and 27.8% in pregnancies which survived >14 gestational weeks). Conclusions The distribution of diandric and digynic triploidy depends on gestational age. The majority of diandric triploid pregnancies is lost in the first trimester of pregnancy. In the second trimester, diandric cases are at least twice less frequent than digynic ones.

Download Full-text