Open Access Research article

Circulating leukocyte telomere length is highly heritable among families of Arab descent

Omar S Al-Attas*, Nasser M Al-Daghri, Majed S Alokail, Khalid M Alkharfy, Assim A Alfadda, Philip McTernan, Greg C Gibson, Shaun B Sabico and George P Chrousos

BMC Medical Genetics 2012, 13:38  doi:10.1186/1471-2350-13-38

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Clarification needed

Dan T.A. Eisenberg   (2013-02-19 17:18)  University of Washington

In a scientific literature which is dominated by studies of peoples of western European descent (Bustamante and others, 2011; Henrich and others, 2010), the work of Al-Attas et al to better understand the diversity of human biology and genetics is particularly valuable. However, reading Al-Attas and colleagues manuscript leaves several questions and points of confusion for me which make it hard to contextualize it within the broader literature on telomere biology.

First, in the separate analyses of maternal and paternal heritability of telomere length, the sample sizes that these statistics are based on are not clear. Further, what these ��h2�� values represent is ambiguous. They seem to be simply beta coefficients (slopes) between a single parents and a child, but are reported as ��h2�� values, which should be twice the single-parent beta coefficient (or equal to the midparental beta co-efficient). Some clarity would be useful here. Since previous studies examining sex-specific heritability patterns of telomere length have used correlation coefficients rather than beta values, it would also be helpful to have these correlation coefficient statistics reported so these results can be compared with past studies.

Second, I have some questions about the laboratory methods used to determine telomere length. A qPCR method was used, but then telomere length measurements are given in kilobases with no explanation for how such a conversion was conducted or how reliable this conversion is. As well, the coefficient of variation across replicate samples is not given as it should be if we are to evaluate the quality of these data.

I hope Al-Attas and colleagues can answer these questions so as to increase the value of their findings for the scientific literature.


Bustamante CD, De La Vega FM, Burchard EG. 2011. Genomics for the world. Nature 475(7355):163-165.
Henrich J, Heine SJ, Norenzayan A. 2010. Most people are not WEIRD. Nature 466(7302):29-29.

Competing interests



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