Handedness

A short presentation about the dominant (genetic) allele for the use of the dominant hand ie being right handed or left handed.

1. HANDEDNESS

2. HANDEDNESS BETTER, FASTER OR MORE PRECISE PERFORMANCE OR INDIVIDUAL PREFERENCE FOR USE IF A HAND KNOWN AS DOMINANT HAND. THE LESS PREFERRED HAND IS CALLED THE NON DOMIANT HAND.

3. TYPES RIGHT HANDEDNESS -THE MOST COMMON KIND -70-90% OF THE WORLD POPULATION LEFT HANDEDNESS -FAR LESS COMMON -APPROXIMATELY 10% OF THE WORLD POPULATION CROSS DOMINANCE/ MIXED HANDEDNESS -CHANGE OF HAND PREFERENCE BETWEEN TASKS -VERY UNCOMMON -ABOUT 1% PREVALENCE AMBIDEXTERITY -EQUAL ABILITY TO USE BOTH HANDS -THOSE WHO LEARN IT STILL TEND TO FAVOR THEIR ORIGINAL DOMINANT HAND

4. CAUSES DIVISION OF LABOR -SPEAKING AND HANDIWORK REQUIRE FINE MOTOR SKILLS. -CENTREVFOR VERBAL PROCESSING AND HANDIWORK ARE CONTROLLED BY LEFT HEMISPHERE OF THE BRAIN AND VISUOSPATIAL PROCESSING IS DONE BY RIGHT HEMISPHERE -THEREFORE RIGHT HANDEDNESS PREDOMINANTS -LEFT HANDEDNESS HAVE A HETEROGENOUS BRAIN ORGANIZATION -LEFT HANDERS ARE LESS LATERALIZED

5. GENETIC FACTORS -COMPLEX INHERITANCE PATERN -A POLYGENIC TRAIT -BASED ON A GENOME WIDE ASSOCIATION STUDY IT WAS FOUND THAT AT LEAST 40 LOCI CONTRIBUTE IN DETERMINING THE TRAIT OF LEFT HANDEDNESS -LRRTMI A BRAIN EXPRESSED IMPRINT GENE INHERITED FROM PATERNAL SIDE WHICH IS PRESENT ON 2p12 ENCODED LEUCINE RICH REPEAT TRANSMEMBRANE PROTEIN -CAG REPEAT LENGTH IN X LINKED ANDROGEN RECEPTORS HAS OPPOSITE EFFECT ON PROBABILITY OF LEFT HANDEDNESS IN MALE AND FEMALE -PCSK6 (PROTEIN CONVERTASE SUBTILISIN/ KEXIN TYPE 6) A PROTEASE CLEAVES NODAL PROPROTEIN WHICH DETERMINES LEFT AND RIGHT SYMMETERY IN BILATERALS FROM MOLLUSC TO VERTEBRATES AND HANDEDNESS IN HUMANS

6. EPIGENETIC FACTORS -25% OF VARIANCE FACTOR AND 75% OF ENVIROMENTAL FACTORS -ASYMMETRIC METHYLATION OF CpG PRENATAL HORMONES -EXPOSURE TO DIETHYLSTIBESTROL (SYNTHETIC ESTROGEN) CAUSED LEFT HANDEDNESS PRENATAL VESTIBULAR SYMMETRY -POSITION OF FETUS IN FINAL TRIMESTER AND SUBSEQUENT BIRTH POSITION -2/3 rd OF FETUSES PRESENT WITH THEIR LEFT OCCIPUT ARE LEFT HANDED -PREMATURITY RESULTS IN DECREASE IN RIGHT HANDEDNESS

7. CORRELATION WITH OTHER FACTORS INTELLIGENCE -IQ DIFFERENCE OF 1.5 -MORE DEVELOPED LANGUAGE CENTERS IN BRAIN -MORE SKILLED MUSICANS AND MATHEMATICIANS HEALTH -LOWER BRITH WEIGHT -NEUROPSYCHIATRIC AND DEVELOPMENT DISORDERS SUCH AS DEPRESSION, BIPOLAR DISORDER, ALCOHOLISM, ETC -40% CHILDREN WITH CEREBRAL PALSY WERE LEFT HANDED -62% INCREASED RISK OF PARKINSON AND BREAST CANCER IN WOMEN

8. GENDER -MALE TO FEMALE RATIO 1.23 -23% MORE MALES ARE LEFT HANDED COMPARED TO FEMALES (DATA COLLECTED FROM 1,787,629 INDIVIDUALS)

9. INTERNATIONAL LEFT HANDERS DAY 13 th AUGUST left-handers everywhere can celebrate their sinistrality (left-handedness) and increase public awareness of the advantages and disadvantages of being left-handed. It celebrates their uniqueness and differences, who are from seven to ten percent of the world's population.