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As a result of congenital abnormality in a normally pentadactyl animal. Polydactyly is very common among domestic cats. For more information, see polydactyly. Polydactyly in early tetrapod aquatic animals, such as in Acanthostega gunnari (Jarvik 1952), one of an increasing number of genera of stem-tetrapods known from the Upper Devonian, which are providing insights into the appearance of tetrapods and the origin of limbs with digits. It also occurs secondarily in some later tetrapods, such as ichthyosaurs. The use of a term normally reserved for congenital defects reflects that it was regarded as an anomaly at the time, as it was believed that all modern tetrapods have either five digits or ancestors that did. Oligodactyly
Oligodactyly (from Greek ὀλιγο- oligo- "few") is having too few digits when not caused by an amputation. It is sometimes incorrectly called hypodactyly or confused with aphalangia, the absence of the phalanx bone on one or (commonly) more digits. When all the digits on a hand or foot are absent, it is referred to as adactyly. Ectrodactyly
Ectrodactyly, also known as split-hand malformation, is the congenital absence of one or more central digits of the hands and feet. Consequently, it is a form of oligodactyly. News anchor Bree Walker is probably the best-known person with this condition, which affects about one in 91,000 people. It is conspicuously more common in the Vadoma in Zimbabwe.
History
AMAN, also known as Chinese Paralytic Syndrome, was first described by a group of Johns Hopkins University and University of Pennsylvania neurologists in collaboration with neurologists from the Second Teaching Hospital of Hebei Medical School and Beijing Childrens Hospital. In 1991, Guy Mckhann, Jack Griffin, Dave Cornblath and Tony Ho from Johns Hopkins University and Arthur Asbury from University of Pennsylvania visited China to study a mysterious epidemic of paralytic syndrome occurring in northern China. Every summer, hundreds of children from rural China developed acute paralysis and respiratory failure. Hospitals were overwhelmed with number of cases and often ran out of ventilators and hospital beds. Examination of these children showed that many of them had acute flaccid paralysis and areflexia but with little or no sensory loss. Electrophysiological testing of these children showed motor axonal loss with occasional conduction block with a lack of demyelinating features and normal sensory potentials. In contrast, the common form of Guillain–Barré syndrome in the West often presents with sensory loss and demyelination on electrophysiology testing and is more common in adults. Later, several autopsies confirmed the focus of the immune attack was at the motor axolemma especially around the nodes of Ranvier. These cases showed deposition of antibody and complement along the motor axolemma and associated macrophage infiltration. References


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