Important findings related to the birth defects Prader-Willi Syndrome (PWS) and Angelman Syndromes, discussed in an article released on August 25, 2008 in PLoS Biology, may help explain imprinted genes in humans.

In humans, two copies of each gene are contributed to a child: one from the mother and one from the father. Imprinted genes are genes that express differently (or stop expressing) depending on whether it is inherited from the mother or father of the child. One of the copies is prevented from working in one of these copies, leaving the other with all expression, which can raise issues if the expression gene is damaged.

These genes have not been fully explained, but according to the kinship theory are influenced by allocation of maternal and paternal resources, such as nourishment or affection. Much investigation has been performed related to the maternal contribution to such genes, but the paternal influence has been largely neglected.

One example of such a gene leads to a syndrome, Prader-Willi Syndrome. PWS children have difficulty suckling after birth and generally have a low body weight. Once weaned from breast milk, they gain large appetites, and they become obese. The Prader-Willi Syndrome Association of the United States cites that the syndrome is found in one out of every 12 to 15 thousand children. While rare, it is considered the most common genetic cause of obesity, and is related to a damaged copy of the gene coming from the father.

Prof. Francisco Ubeda of the University of Tennessee, Knoxville, investigated the relationship between this gene’s expression and the amount of care given to the child by his father. He as observed that PWS children experience changes that imply near reversal of the syndrome when they receive significant paternal resources. Ubeda found that, as the contribution of resources from the father increased, the PWS copy that is expressed shifts. This shows that the paternal resources can have a significant impact on imprinted genes. This relates to the typical pattern of early human development. “Before weaning, the mother has the monopoly on providing resources directly to her offspring,” Ubeda says.”After weaning, the father directly provides a greater share of resources to his offspring.”

Ubedo points out that this finding will likely not affect PWS treatment in the near future, but it has many implications for a greater understanding of imprinted genes. “I don’t have any sense that this will somehow lead to a cure for PWS, but it does present a new area for those interested in the disease to study and hopefully a new understanding of how the disease functions.” He claims that the larger effects of this work may be situated in the discovery that even a small contribution from the father early in development can affect expression of these genes. This new finding answers many of the questions caused by this and similar conditions that do not seem to be entirely dictated by the mother’s influence.

Evolution of genomic imprinting with biparental care: Implications for Prader-Willi and Angelman syndromes.
Ubeda F
PLoS Biol 6(8): e208.
doi:10.1371/journal.pbio.s0060208
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Written by Anna Sophia McKenney