The Paternal Age Effect

The relationship between advanced paternal age and genetic disorders in offspring was noticed by Wilhem Weinberg, a physican who delivered thousands of babies.
Weinberg was born in Stuttgart and studied medicine at Tübingen and Munich, receiving an M.D. in 1886.

He observed that the last born, or late born children were sometimes abnormal.

There is much literature on the paternal age effect.

What is advanced paternal age 33 35 40?

There is disagreement about the definition, advanced maternal age is 35, from the evidence I've collected 33-35 is when spontaneous mutations in sperm begin to increase rapidly. These mutations may affect the next generation or future generations.


New mutations on the X chromosome are usually not evident in the children. They are transmitted to daughters who are at risk for having sons with X-linked diseases. This is an indirect paternal age effect; it is the effect of the age of the maternal grandfather.

Examples of autosomal dominant conditions associated with advanced paternal age include achondroplasia, neurofibromatosis, Marfan syndrome, Treacher Collins syndrome, Waardenburg syndrome, thanatophoric dysplasia, osteogenesis imperfecta, and Apert syndrome.

Examples of X-linked conditions associated with increased maternal grandfather's age include fragile X, hemophilia A (factor VIII deficiency), hemophilia B (factor IX deficiency), Duchenne muscular dystrophy, incontinentia pigmenti, Hunter syndrome, Bruton-type agammaglobulinemia, and retinitis pigmentosa.