Sunday, March 18, 2007

Age of the father and development potential

1: Contracept Fertil Sex (Paris). 1992 Oct;20(10):942-5. Links
[Age of the father and development potential][Article in French]
Auroux MR.
PIP: Testicular aging, like ovarian aging, concerns not just the individual but also the quality of the gametes and hence of the offspring. The 1st signs of testicular aging appear early. Beginning around the age of 30, the vascularization begins to thin, with a progressive decline in the density of the capillaries. The membrane of the seminiferous tubules, an essential element of the hematotesticular barrier, begins to thicken and the number of Sertoli cells begins to decline. Endocrine effects usually appear a decade later, but individual variations are considerable. These modifications are accompanied by a slow decline in the number of sperm and alterations in their morphology and motility. Male fertility declines progressively with age. The quality of the gametes is lower among very young males and increases to a maximum at about age 30. Paternal aging may be responsible for well-defined syndromes in the offspring. Paternal aging has long been recognized as a factor in dominant autosomal mutations causing macroscopic malformations such as achondroplasia, Apert syndrome, Marfan's syndrome, fibrodysplasia ossificans progressiva, and others. The frequency of each disorder is very low, but the total number of recognized disorders of this type exceeds 1000, multiplying the risks so that the .3-.5% risk of anomalies due to paternal aging after 40 is comparable to the risk of trisomy 21 for women aged 35-40. Dominant autosomal mutations can also be responsible for less marked anomalies such as Recklinghausen's neurofibromatosis. Some authors believe that recessive mutations linked to the X chromosome causing hemophilia or Duchenne muscular dystrophy can also result from paternal aging. Some evidence suggests that for a given maternal age, paternal age results in subtle and continuous declines in cerebral functioning. A psychometric study of 1700 military recruits in Nancy, France, in 1985 who were 18 years old showed that sons of very young fathers and of older fathers did less well on the tests. The study is being repeated on 12,000 recruits in the Paris area in 1989-90 to verify the results. Efforts will be made to separate the influence of socioeconomic status and birth order on the results.

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