Signs and symptoms
A list of the common side effects broken down by frequency.Very frequent

Abnormal gastrointestinal tract
Absent pectoral muscles
Brachydactyly (Short fingers)
Dextrocardia
Diaphragmatic hernia/defect
Humerus absent/abnormal
Liver/biliary tract anomalies
Maternal diabetes
Oligodactyly/missing fingers
Radius absent/abnormal
Rhizomelic micromelia (relatively shorter proximal segment of the limbs compared to the middle and the distal segments)
Sparsity or abnormality of axillary hair on affected side
Syndactyly of fingers (webbing)
Ulna absent/abnormal
Upper limb asymmetry
Abnormal rib
Simian crease on affected sideFrequent

Hypoplastic/absent nipples
Scapula anomalyOccasional

Agenesis/hypoplasia of kidneys
Encephalocele/exencephaly
Abnormal morphology of hypothalamic-hypophyseal axis
Abnormal function of hypothalamic-hypophyseal axis
Microcephaly
Preaxial polydactyly
Ureteric anomalies (reflux/duplex system)
Vertebral segmentation anomalyIt is usually considered a unilateral condition. Some have claimed that the term can be applied in bilateral presentation, but others recommend using alternate terminology in those cases. Causes
The cause of Poland syndrome is unknown. However, an interruption of the embryonic blood supply to the arteries that lie under the collarbone (subclavian arteries) at about the 46th day of embryonic development is the prevailing theory.The subclavian arteries normally supply blood to embryonic tissues that give rise to the chest wall and hand. Variations in the site and extent of the disruption may explain the range of signs and symptoms that occur in Poland syndrome. Abnormality of an embryonic structure called the apical ectodermal ridge, which helps direct early limb development, may also be involved in this disorder. Diagnosis
Poland syndrome is usually diagnosed at birth, based upon the physical characteristics. Imaging techniques such as a CT scan may reveal the extent to which the muscles are affected. The syndrome varies in severity and as such is often not reported until puberty, when lopsided growth becomes apparent.
Clarkson published his series of three cases and named the syndrome after Poland in his article. Notable cases
TV presenter Jeremy Beadle (1948–2008) was known for having this condition. His Poland syndrome manifested itself in the form of his disproportionately small right hand. Olympic boxer Jérôme Thomas is also affected by Poland syndrome, as his left arm and hand are significantly shorter and smaller than his right. Thomas also lacks a left pectoral muscle. PGA Tour golfer Bryce Molder has Poland syndrome, with an absent left pectoral muscle and a small left hand. Several surgeries in his childhood repaired syndactyly on the left hand. Actor Ted Danson, famous for starring in the TV show Cheers, admitted he had the condition in 2000 to Orange Coast magazine and said that he was bullied as a child because of it. Formula One World Champion Fernando Alonso is affected by Poland syndrome; he is missing the right pectoral muscle. Cricketer Lewis Hatchett was born with Poland syndrome. Australian Paralympian Mathew Silcocks is affected by Poland syndrome. Hailey Dawson of Nevada (born 2010) has a missing right pectoral muscle and is missing three fingers on her right hand due to the condition. She has thrown out the ceremonial first pitch at all 30 Major League Baseball parks, using a 3D-printed robotic right hand fitted for her by engineers at the University of Nevada, Las Vegas. Actor Gary Burghoff, best known for the television series M*A*S*H, has Poland syndrome manifesting in brachydactyly on his left hand.