Second to fourth digit ratio and dyslexia: no evidence for an association between reading disabilities and the 2D:4D ratio

Gelder, Mayke van; Tijms, Jurgen; Hoeks, Jan

doi:10.1017/s0012162205211477

Cited by 12 publications

(7 citation statements)

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“…One genome-wide linkage analysis suggested a locus on Xq26 [199]. A nearby susceptibility locus in a single extended family has also been reported [198].…”

Section: What Might Cause An Extreme Male Brain?mentioning

confidence: 97%

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Why Are Autism Spectrum Conditions More Prevalent in Males?

et al. 2011

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Autism Spectrum Conditions (ASC) are much more common in males, a bias that may offer clues to the etiology of this condition. Although the cause of this bias remains a mystery, we argue that it occurs because ASC is an extreme manifestation of the male brain. The extreme male brain (EMB) theory, first proposed in 1997, is an extension of the Empathizing-Systemizing (E-S) theory of typical sex differences that proposes that females on average have a stronger drive to empathize while males on average have a stronger drive to systemize. In this first major update since 2005, we describe some of the evidence relating to the EMB theory of ASC and consider how typical sex differences in brain structure may be relevant to ASC. One possible biological mechanism to account for the male bias is the effect of fetal testosterone (fT). We also consider alternative biological theories, the X and Y chromosome theories, and the reduced autosomal penetrance theory. None of these theories has yet been fully confirmed or refuted, though the weight of evidence in favor of the fT theory is growing from converging sources (longitudinal amniocentesis studies from pregnancy to age 10 years old, current hormone studies, and genetic association studies of SNPs in the sex steroid pathways). Ultimately, as these theories are not mutually exclusive and ASC is multi-factorial, they may help explain the male prevalence of ASC.

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“…One genome-wide linkage analysis suggested a locus on Xq26 [199]. A nearby susceptibility locus in a single extended family has also been reported [198].…”

Section: What Might Cause An Extreme Male Brain?mentioning

confidence: 97%

“…Reading Disorder/Dyslexia: Two studies have failed to find a relation between 2D∶4D (digit) ratio (as a proxy for fT) and dyslexia [115],[198]. One genome-wide linkage analysis suggested a locus on Xq26 [199].…”

Section: What Might Cause An Extreme Male Brain?mentioning

confidence: 99%

Why Are Autism Spectrum Conditions More Prevalent in Males?

et al. 2011

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“…But our finding is in concurrence with the findings of two other studies, which also reported no association between 2D:4D ratio and dyslexia. A study done in Netherland on children with dyslexia with a phonological deficit showed no evidence for an association between reading disabilities and the 2nd digit to 4th digit ratio, also showed no support for the assumed relation between the 2nd digit to 4th digit ratio and prenatal testosterone [10].…”

Section: Discussionmentioning

confidence: 92%

2nd to 4th Digit Ratio (2D:4D) – Is It a Marker for Dyslexia ?

Ramasamy¹,

Thaj²,

Ibrahim³

2019

Indian Journal of Mental Health

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Background: Specific learning disorder in general called as dyslexia is a neuro developmental disorder, which occurs more commonly in males (Male:Female ratio is 4:1), there are evidence to suggest role of prenatal gonadal hormone exposure in neurodevelopment. However, studies on association between 2nd to 4th digit ratio and dyslexia are mixed. Objective: To compare the 2nd and 4th digit ratio (2D:4D) of both hands between children with dyslexia and children without dyslexia. Methodology: A case control study, recruited 30 children with dyslexia and 30 age and education matched normal controls, after getting informed consent from their parents. Collected socio demographic details, applied CARS, Schonell's reading and spelling test, followed by detailed evaluation by psychiatrist and clinical psychologist, including psychological testing to confirm the diagnosis of dyslexia. The digit length of index and ring finger on both hands of all children were measured using Vernier Calliper by direct method. Results: In both the hands 2D:4D ratio was more in children with dyslexia than normal children, but the difference was not significant (p-0.146). Analysis of only male samples showed digit ratio is higher in dyslexic children than normal children; which were significant (p-0.03). Conclusion: Our study does not support an association between digit ratios and dyslexia; however, trend towards higher ratio in dyslexia especially in male children are interesting and needs further exploration. Need more studies in this area to form a definite conclusion.

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“…Recent evidence, however, indicates that the ratio between the length of the index finger (2D) and the ring finger (4D) is stable over the lifetime and is inversely related to fetal testosterone exposure (95,96). Therefore, the studies used the 2D:4D ratio as a marker of fetal testosterone exposure to investigate the associations between prenatal testosterone exposure and RD, phonological processing, and sensory sensitivity; they did not demonstrate any differences in a large group of dyslexic and normal reading children (97,98). These findings will challenge the validity of theories that allocate a prominent role to fetal testosterone exposure in the etiology of dyslexia and its sensory impairments.…”

Section: Resultsmentioning

confidence: 99%

Neurobiological Approaches on Brains of Children with Dyslexia

Çaylak

2009

Academic Radiology

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Second to fourth digit ratio and dyslexia: no evidence for an association between reading disabilities and the 2D:4D ratio

Cited by 12 publications

References 0 publications

Why Are Autism Spectrum Conditions More Prevalent in Males?

Why Are Autism Spectrum Conditions More Prevalent in Males?

2nd to 4th Digit Ratio (2D:4D) – Is It a Marker for Dyslexia ?

Neurobiological Approaches on Brains of Children with Dyslexia

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