Left-handedness (left lateral)

Left-handedness is the preference for using primarily the left hand to perform everyday activities, such as writing, eating, or throwing an object. Left handedness is less common than right handedness and has been linked to certain neuropsychiatric traits such as schizophrenia and bipolar disorder.

Left-handed people have a definite preference for using the left hand over the right, and this can be seen from early stages of development, even in utero, when the embryo begins to move only one arm. Constant use of one hand throughout life can cause changes in bone and bone density. In addition, it has been observed that left laterality is related to language lateralization in the brain, that is, the side that plays a major role in language. Its connection with some neuropsychiatric traits, such as schizophrenia and bipolar disorder, has also been investigated.

Genetic influence may play a crucial role in explaining the differences in language processing, spatial skills and emotions between left- and right-handers. However, the exact etiology of this trait is not yet fully understood, although it has been shown to be highly polygenic. In addition to genetic influence, left laterality can also be explained by environmental factors that could affect from prenatal stages. However, the precise effects of such environmental factors are not yet fully known.

The worldwide prevalence of left-handedness is about 10%, and it is also higher in males than in females. The problem with the study of left-handedness is that non-right-handed people have historically been forced to use their right hand for everyday tasks, which has led to some left-handed or ambidextrous people becoming right-handed due to this imposition. This has caused the rate of forced right-handedness to vary between cultures and, although it has decreased in recent decades, it may have affected the accuracy of left-handed prevalence statistics.

Number of observed variants

13.5 million variants

Number of risk loci

36 loci

Genes analyzed

ABT1 ANKS1B ATP1B1 ATXN2L BCR BUB3 C11orf58 CADM1 CNTN3 FAM171B FES FOXG1 GPR12 LINC02210-CRHR1 MAP2 MDC1 MDGA2 NDRG1 NPAS4 PAX4 PITPNB PPP1R21 ROBO2 RSF1 SH3RF3 SHOX2 SLC39A8 SNTB2 ST3GAL3 TBC1D5 TMEM161B TRIM36 TUBA1B TUBB2A TUBB3 TUBB4A ZNF366

Bibliography

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