LIONEL PENROSE, THE PATERNAL AGE EFFECT ON GENETIC HEALTH OF OFFSPRING

"Male-mediated anomalies of pregnancy outcomes are currently well known in both humans and animals."

In 1955 Lionel Penrose wrote "Parental Age and Mutations" which was published in Lancet,ii,312-313.

Will the scientists assay the spermatagonia of the fathers of the children with copy number variations?




The effects of parental age upon the occurrence of abnormalities in offspring never ceased to intrigue Penrose. It was Weinberg who first noted the phenomenon in 1912, and there were others who suggested that it was the father's not the mother's age that played a significant role in the occurrence of infants with, for example, achondroplasia. However, it was Penrose who, again using the partial correlation method employed by Wright, provided the data to prove the hypothesis. His results were a mirror image of those found in families with Down syndrome. In other words, if the maternal age was kept constant, a significantly positive correlation (+0.273) was found between the paternal age and the incidence of achondroplasia, whereas the maternal age effect disappeared completely if the paternal age was regressed out. Furthermore, Penrose noted that the statistical significance of the paternal age effect increased considerably when nonsurviving infants with achondroplasia were excluded from the calculations (PENROSE 1955 , PENROSE 1957 ). It is possible, although no proof exists from the old data, that the infants with "achondroplasia" who died neonatally or shortly thereafter had different diagnoses of more severe, perhaps lethal, short-limbed dwarfing disorders. The survivors represented true instances of new (paternally derived) mutations of the gene.

Together with Haldane, Penrose also studied the paternal age effect upon mutations of genes located on the X chromosome. Haldane had accurately postulated an increased occurrence of hemophilia in the grandsons of older maternal grandfathers, implying another example of a higher mutation rate in males. Four decades later, it was Crow who finally completed the story by summarizing data showing that, at the molecular level, the rate for base substitutions (the cause of the achondroplasia mutation) is indeed higher in males than in females; he also showed that the phenomenon can be attributed partially to the larger number of cell divisions, estimated to be about 430 at age 30 in the male, as contrasted with the female germ line, in whom there are only about 24 divisions from zygote to egg (CROW 1997A , CROW 1997B ). More specifically, the mutation in achondroplasia, in the fibroblast growth factor receptor 3 gene (FGFR3) on 4p16.3, consists of a single substitution of the normal glycine residue by an arginine residue at codon 380. This same Gly380Arg mutation is, surprisingly, present in almost all of the hundreds of patients with achondroplasia who have had mutational analysis to date, and it is of paternal origin in those in which the parental origin could be determined (HORTON 1997 ). Thus, we owe our understanding of the paternal age factor, its causes as well as underlying mechanisms, to the imaginatively creative minds of three generations of genetics heroes.

Alzheimer's and Paternal Age & Myelin

George Bartzokis,M.D.


Visiting Professor

Laboratory of Neuro Imaging,
Department of Neurology, UCLA School of Medicine
635 Charles Young Drive South, Suite 225
Los Angeles, CA 90095-7332



Education

1975-1979, BA Harvard University, Cambridge, MA
1979-1983, MD Yale Medical School, New Haven, CT
1983-1984, Internship, UCLA/WLA VA, Los Angeles, CA
1984-1987, Psychiatry Residency, UCLA NPI, Los Angeles, CA
1987-1990, Schizophrenia Research Fellow, UCLA Dept of Psychology, Los Angeles, CA


Research

Development of brain imaging biomarkers for use in diagnosis of neuropsychiatric disorders and medication development
Assessing brain maturation and degeneration trajectories over the life-span in normal populations and how neuropsychiatric disorders interact with these processes


Projects

Myelin breakdown in aging and Alzheimer's disease
In vivo quantification of age-related increases in brain iron levels
Evaluation of brain maturational trajectories in normal adults and patientss with neuropsychiatrc diseases


Skills

Quantification of brain iron levels
Quantification of limbic structures volumes
Quantification of brain myelination
Quantification of myelin integrity
Clinical trials
Administration of multidisciplinary teams


Honors

U.S. Patent, Method for Quantitatively Measuring Stored Iron in Tissue Using MRI










This quote is not from a published paper.
I had asked Dr. Bartzokis why risk of non-familial autism, schizophrenia, MS, and Alzheimer's risk increases with the age of the father at a person's birth.



"The issue is that the older man will have sperm that has undergone more divisions and therefore had more chances to have mutations.
The COMPLEXITY of the myelination process makes it more vulnerable to mutations. I am not talking of one specific mutation. Many things could MANIFEST in the myelination or myelin breakdown process because it is so vulnerable - something going slightly wrong will impact it while it will not impact bone growth or the heart. A good example is ApoE4 - whatever else it may affect, it manifests in the reduced capacity of myelin repair and earlier onset of AD."

THE AGE OF THE FATHER AND THE HEALTH OF FUTURE GENERATIONS

THE AGE OF THE FATHER AND THE
HEALTH OF FUTURE GENERATIONS
Word Count: 903
　
Leslie B. Raschka M.D., Associate Professor (retired),
Department of Psychiatry, University of Toronto
Address: 27 Edgecombe ave, Toronto, Ontario, Canada
M5N 2Xl, Tel. (416) 783-6938
2
Abstract
Purpose: To assess the role of paternal age in the origin of genetic illness in future generations.
Data Sources: All reference data originated in English language international scientific literature and findings of original research conducted by myself.
Study Selection: Original articles published between 1938 and 1998 were selected according to the stated purpose. One article was written by myself.
Data Extraction: The present paper deals with 4 subtopics: andrology, genetics, pathology, and psychiatry.
Results: Nine articles reporting on 1399 patients described the deterioration of the quality of semen related to ageing. Five articles reported an increased mutation rate in the male germ cells as compared to the female germ cell. Twenty-four articles reported on 1230 patients and related studies described paternal age effect on increased mutation rate causing genetic illness. Eight articles reporting on 10,347 patients described increased prevalence of mental illness as related to older paternal age.
Conclusions: The age of the father is an important determinant of the health of future generations. Children conceived by fathers older than 34 years of age are at increased risk for genetic illness due to recent mutation in the male germ cell.
3The genetic illness of a child could originate in a mutation related to the age of the father or to a mutation in the spermatogenesis caused by ageing in previous generations. The ageing process in the male is an important, probably the most important, cause of genetic illness in human populations.
　Key Words: Age of the father, mutation, genetic illness
4 Demographic changes taking place in the 20th Century have directed attention to all possible determinants of the health of future generations. The relationship between maternal age and Down Syndrome is a currently recognized scientific fact. The study of the reproductive efficiency of the male is also relevant to the health of future generations. Most children are born healthy regardless of paternal age; however, the age of the father is a determinant of ill health for a significant minority in future generations.
　
5 Andrology
Ageing in the male is expressed in a progressive decline both in the quality and quantity of the sperm (1). Changes include a decrease in motility (2), decreased vitality and an increased percentage of malformed sperm (3, 4, 5, 6, 7). The deterioration associated with ageing can be noticed first in men between the ages of 35 to 40 years (8, 9).
　
6 Genetics
The mutation rate is higher in the male than in the female germ cell (10, 11, 12, 13, 14). While the ageing male germ cell is especially sensitive to mutation (15) there is a significant difference in mutation, rates among different genes. There is evidence that mutation frequencies for a number of different genes causing illness increase with advancing paternal age. The rate of increase differs among different genes (16); not all genes are subject to the paternal age effect. Almost all new mutations were reported to occur in the male germ cell; however, paternal age effect is not equally pronounced in all mutations (12). It is operant in recent germline mutations. Inherited illnesses such as hemophilia A have their origins in mutations in earlier generations where, for example, increased maternal grandparental age was found and new germline mutation related to increased paternal age transmitted to future generations can result in hereditary illness. In the development of illness, more than one gene can be involved. The phenotypic expression can be influenced by modifying genes. The importance of mutations for the health of future generations was born out by the Bulletin of the World Health Organization 1986 (17), which states that about 1% of children will be born with a serious genetic disease and another 1% will develop a serious genetic illness later in life.
7 Pathology
The relationship between increased paternal age and pathological conditions of known genetic origin was reported for achondroplasia in nineteen publications (15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, 26, 27, 28, 29, 30, 31, 32, 33, 34); for Apert Syndrome in sixteen publications (15, 19, 20, 22, 23, 24, 25, 26, 27, 28, 30, 31, 32, 33, 34, 35); on Marfan Syndrome in thirteen publications (15, 20, 21, 22, 23, 25, 26, 27, 30, 31, 32, 33, 34); on osteogenesis imperfecta in five publications (16, 19, 24, 25, 29); on basal cell naevus syndrome in three publications (22, 26, 32); in Waardenburg Syndrome in five publications (22, 26, 31, 32, 33); on Crouzon Syndrome in seven publications (22, 26, 28, 31, 32, 33, 35); on oculo-denta; digital syndrome in four publications (22, 26, 31, 32); on thanatophoric dysplasia in three publications (28, 29, 35); on Pfeiffer Syndrome in three publications (28, 32, 35); on tuberous sclerosis in three publications (31, 33, 36); on multiple endocrine neoplasm in three publications (32, 34, 37); on myositis ossificans in nine publications (15, 19, 21, 22, 24, 30, 31, 32, 33); and on Treacher Collins disease, four publications (22, 26, 31, 33). All of these illnesses are transmitted in an autosomal dominant fashion. Increased risk for X-linked conditions associated with increased maternal grand-parental age is known to exist regarding classical hemophilia and was reported in nine publications (15, 17, 23, 25, 26 31, 32, 34, 38). This is also true for Lesch-Nyhan syndrome, reported in five publications (10, 17, 27, 31, 38). The mutation is transmitted to the child through carrier mothers.
8Psychiatry
Mutations occurring in the course of gametogenesis in the male and the association of psychosis was described in one article (39). Older maternal and paternal age in schizophrenia was reported in four articles (39, 40, 41, 42). My own study involving 574 patients has shown that the increased age of the father is a causative factor in a sub-group of the schizophrenic population (43). Two other articles, reporting on 662 and 8000 patients respectively, confirmed my conclusions, as well as indicating that increased maternal age was secondary to increased paternal age (41, 42). Three articles reporting on 1081 patients described increased paternal age in Alzheimer’s disease (44, 45, 46).
　
9 Discussion
All genetic illnesses have their origin in a distant or recent mutation. Paternal age is an important determinant of mutation frequency in new germ cell mutation, causing both autosomal dominant and X-linked recessive illnesses. The role of other mutagenic factors is not the subject of this study. The results of my own research are supported by other information which indicates that the leading cause of genetic illness present in human populations is the ageing process in the male. Conceiving children by men younger than 35 years of age would prevent many genetic illnesses in future generations.
　
10 Bibliography
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3. Holstein A F. Spermatid Differentiation In Man During Senescence. In. : Andre J, ed. Proceedings of the Fourth International Symposium on Spermatology; 1982 June; The Hague. Martinus Nijhoff, 1983: 15-18.
4. Homonnai Z T, Fainman N, David M P, et al. Semen Quality and Sex Hormone Pattern of 39 Middle Aged Men. Andrologia 1982; 14(2): 164.
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7. Sternbach H. Age-Associated Testosterone Decline in Men: Clinical Issues for Psychiatry. Am J Psychiatry 1998; 155: 1310.
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8. Bishop M W H. Aging and Reproduction in the Male. J Reprod Fert 1970; (Suppl. 12): 65.
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25. Carothers A D, McAllion S J, Paterson C R. Risk of dominant mutation in older fathers: evidence from osteogenesis imperfecta. J Med Genet 1986; 23: 227.
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2. Bordson B L, Leonardo VS. The appropriate upper age limit for semen donors: a review of the genetic effects of paternal age. Fertil Steril 1991; 56: 397.
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3. Urikami K, Adachi Y, Takahashi K. A Community-Based Study of Parental Age in Alzheimer-Type Dementia in Western Japan. Arch Neurol 1988; 45: 375.
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Diabetes age of parents etc risk factor 2005

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