Also called: Single Transverse Palmar Crease · STPC · Simian Crease

Where on the hand: A single horizontal crease running straight across the palm from the radial edge to the percussion, replacing what would normally be two separate creases. The Head and Heart lines are, in effect, fused into one.

What it looks like: One clean transverse crease bisecting the palm, with no separate Heart line above it or Head line below it.

In palmistry it is read as intensity and single-mindedness — a fusion of thought and feeling, so that the person cannot separate what they think from what they feel. It carries great potential for strong will and focus, ambition and drive, especially when supported by education and family opportunity. Indian sources read it as a rare line indicating mental determination and self-awareness.

Western reading: The same reading, plus the modern medical caveats.

Read with care: CLINICAL FACTS, which must accompany any reading. PREVALENCE. Roughly 1–3% is a Northern-European figure and should not be given as a global rate. Measured prevalence varies enormously by population: Swiss 1.2%, Ethiopians 5.0% (Anat Cell Biol 2022, n=832), Koreans 9.1% (Park et al., Anat Cell Biol 2010, n=3216), Central Indians 14.4% (Sharma & Sharma, Int J Morphol 2011, n=1000), Nepalese children 14.6% (KUMJ 2011, n=2063). Higher rates in East Asian and South Asian populations are well documented; a claim of higher rates in Native American populations is not — the nearest figure in the comparative literature (Inuit, 1.3%) is near the bottom of the range. WHAT IT ACTUALLY IMPLIES — the number that matters. About 45% of people with Down syndrome carry the crease (the published range is 33–80%, so 45% is a textbook midpoint, not a precise value). Running that the other way: with Down syndrome at ~1 in 700 births and the crease in ~3% of the population, the chance that a person with the crease has Down syndrome is about 2% — and about 0.6% at the ~10% crease prevalence typical of Asian populations. Roughly 98–99% of people with a single transverse crease have no chromosomal condition at all. A list of associated syndromes without that arithmetic reads as a risk list, and it is not one. ASSOCIATIONS. Statistically associated with Down syndrome, Cri du Chat, Klinefelter, Wolf–Hirschhorn, Noonan, Patau, Edwards, IDIC-15/Dup15q, Aarskog–Scott, leukocyte adhesion deficiency-2, nevoid basal cell carcinoma syndrome, Robinow, Poland syndrome and craniosynostosis. Fetal alcohol syndrome has been REMOVED from this list: the only study to test it directly (n=427, 237 with FASD, two classification systems) found no significant association, and the crease actually described in FAS is the 'hockey stick' crease, a different feature. The crease is not predictive of any of these conditions, because it is also found in people with no medical condition whatever. Never suggest a diagnosis from it. THE PERSONALITY READING BELOW IS ALSO UNFOUNDED. 'Cannot separate what they think from what they feel', 'all-or-nothing', 'difficulty modulating emotion' — these have no evidential basis, and attaching them to a feature best known as a Down syndrome marker, and carried by up to 15% of healthy people in some populations, risks reading as a description of intellectual disability. Treat it as tradition and say so. On how creases form: palmar creases are laid down between about week 7 (digital) and week 12 (palmar transverse), which the sources state correctly — but the common gloss that they are 'determined by fetal hand flexion' inverts the causality. Kimura & Kitagawa showed digital creases appear at 7–9 weeks while spontaneous digit flexion does not begin until about week 11.5. The flexion hypothesis was refuted on timing; creases form under genetic control.

is not predictive of any of these conditions since it is also found in persons with no abnormal medical conditions.Wikipedia, Single transverse palmar crease

a lot of energy or enthusiasmmodern palmistry sources