The imprinted gene and parent-of-origin effect database now includes parental origin of de novo mutations

The imprinted gene and parent-of-origin effect database () consists of two sections. One section catalogues the current literature on imprinted genes in humans and animals. The second, and new, section catalogues current reports of parental origin of de novo mutations in humans alone. The addition of a catalogue of de novo mutations that show a parent-of-origin effect expands the scope of the database and provides a useful tool for examining parental origin trends for different types of spontaneous mutations. This new section includes >1700 mutations, found in 59 different disorders. The 85 imprinted genes are described in 152 entries from several mammalian species. In addition, >300 other entries describe a range of reported parent-of-origin effects in animals

The Ups and Downs of Mutation Frequencies during Aging Can Account for the Apert Syndrome Paternal Age Effect

Apert syndrome is almost always caused by a spontaneous mutation of paternal origin in one of two nucleotides in the fibroblast growth factor receptor 2 gene (FGFR2). The incidence of this disease increases with the age of the father (paternal age effect), and this increase is greater than what would be expected based on the greater number of germ-line divisions in older men. We use a highly sensitive PCR assay to measure the frequencies of the two causal mutations in the sperm of over 300 normal donors with a wide range of ages. The mutation frequencies increase with the age of the sperm donors, and this increase is consistent with the increase in the incidence rate. In both the sperm data and the birth data, the increase is non-monotonic. Further, after normalizing for age, the two Apert syndrome mutation frequencies are correlated within individual sperm donors. We consider a mathematical model for germ-line mutation which reproduces many of the attributes of the data. This model, with other evidence, suggests that part of the increase in both the sperm data and the birth data is due to selection for mutated premeiotic cells. It is likely that a number of other genetic diseases have similar features

Student Attitudes Contribute to the Effectiveness of a Genomics CURE

The Genomics Education Partnership (GEP) engages students in a course-based undergraduate research experience (CURE). To better understand the student attributes that support success in this CURE, we asked students about their attitudes using previously published scales that measure epistemic beliefs about work and science, interest in science, and grit. We found, in general, that the attitudes students bring with them into the classroom contribute to two outcome measures, namely, learning as assessed by a pre- and postquiz and perceived self-reported benefits. While the GEP CURE produces positive outcomes overall, the students with more positive attitudes toward science, particularly with respect to epistemic beliefs, showed greater gains. The findings indicate the importance of a student\u27s epistemic beliefs to achieving positive learning outcomes

The Paternal-Age Effect in Apert Syndrome Is Due, in Part, to the Increased Frequency of Mutations in Sperm

A paternal-age effect and the exclusive paternal origin of mutations have been reported in Apert syndrome (AS). As the incidence of sporadic AS births increases exponentially with paternal age, we hypothesized that the frequency of AS mutations in sperm would also increase. To determine the frequency of two common FGFR2 mutations in AS, we developed allele-specific peptide nucleic acid–PCR assays. Analyzing sperm DNA from 148 men, age 21–80 years, we showed that the number of sperm with mutations increased in the oldest age groups among men who did not have a child with AS. These older men were also more likely to have both mutations in their sperm. However, this age-related increase in mutation frequency was not sufficient to explain the AS-birth frequency. In contrast, the mutation frequency observed in men who were younger and had children with AS was significantly greater. In addition, our data suggest selection for sperm with specific mutations. Therefore, contributing factors to the paternal-age effect may include selection and a higher number of mutant sperm in a subset of men ascertained because they had a child with AS. No age-related increase in the frequency of these mutations was observed in leukocytes. Selection and/or quality-control mechanisms, including DNA repair and apoptosis, may contribute to the cell-type differences in mutation frequency

The Paternal-Age Effect in Apert Syndrome Is Due, in Part, to the Increased Frequency of Mutations in Sperm

t of men ascertained because they had a child with AS. No age-related increase in the frequency of these mutations was observed in leukocytes. Selection and/or quality-control mechanisms, including DNA repair and apoptosis, may contribute to the cell-type differences in mutation frequency. Much has been written about the "mutagenic male" (Hurst and Ellegren 2002) and the higher male-to-female mutation rate in many genetic disorders (Vogel and Rathenberg 1975; Crow 2000). Conventional wisdom says that the greater number of germ-cell divisions in males compared with females contributes to the higher mutation frequency in males (Penrose 1955), which manifests as an increased incidence with paternal age of de novo cases of disorders, as well as paternally derived mutations (Moloney et al. 1996; Shuffenecker et al. 1997; Wilkin et al. 1998; Glaser et al. 2000). However, the linear increase with age in the number of divisions does not fully explain the exponential increase with paternal ag

Paternal Origin of FGFR2 Mutations in Sporadic Cases of Crouzon Syndrome and Pfeiffer Syndrome

Crouzon syndrome and Pfeiffer syndrome are both autosomal dominant craniosynostotic disorders that can be caused by mutations in the fibroblast growth factor receptor 2 (FGFR2) gene. To determine the parental origin of these FGFR2 mutations, the amplification refractory mutation system (ARMS) was used. ARMS PCR primers were developed to recognize polymorphisms that could distinguish maternal and paternal alleles. A total of 4,374 bases between introns IIIa and 11 of the FGFR2 gene were sequenced and were assayed by heteroduplex analysis, to identify polymorphisms. Two polymorphisms (1333TA/TATA and 2710 C/T) were found and were used with two previously described polymorphisms, to screen a total of 41 families. Twenty-two of these families were shown to be informative (11 for Crouzon syndrome and 11 for Pfeiffer syndrome). Eleven different mutations in the 22 families were detected by either restriction digest or allele-specific oligonucleotide hybridization of ARMS PCR products. We molecularly proved the origin of these different mutations to be paternal for all informative cases analyzed (P=2.4×10(-7); 95% confidence limits 87%–100%). Advanced paternal age was noted for the fathers of patients with Crouzon syndrome or Pfeiffer syndrome, compared with the fathers of control individuals (34.50±7.65 years vs. 30.45±1.28 years, P<.01). Our data on advanced paternal age corroborates and extends previous clinical evidence based on statistical analyses as well as additional reports of advanced paternal age associated with paternal origin of three sporadic mutations causing Apert syndrome (FGFR2) and achondroplasia (FGFR3). Our results suggest that older men either have accumulated or are more susceptible to a variety of germline mutations