The identified mutation for SHSF syndrome (split-hand/split-foot syndrome) a duplication on 10q24, and not a mutation of the tp63 gene as in families affected by EEC syndrome (ectrodactyly–ectodermal dysplasia–cleft syndrome). The p63 gene plays a critical role in the development of the apical ectodermal ridge (AER), this was found in mutant mice with dactylaplasia. Embryology
Some studies have postulated that polydactyly, syndactyly and cleft hand have the same teratogenic mechanism. In vivo tests showed that limb anomalies were found alone or in combination with cleft hand when they were given Myleran. These anomalies take place in humans around day 41 of gestation. Diagnosis
Classification
There are several classifications for cleft hand, but the most used classification is described by Manske and Halikis see table 3. This classification is based on the first web space. The first web space is the space between the thumb and the index finger. Table 3: Classification for cleft hand described by Manske and Halikis

Treatment
The treatment of cleft hand is usually invasive and can differ each time because of the heterogeneity of the condition. The function of a cleft hand is mostly not restricted, yet improving the function is one of the goals when the thumb or first webspace is absent.The social and stigmatising aspects of a cleft hand require more attention. The hand is a part of the body which is usually shown during communication. When this hand is obviously different and deformed, stigmatisation or rejection can occur.
Nowadays, this "atypical cleft hand" is referred to as symbrachydactyly and is not a subtype of cleft hand. Notable cases
Bree Walker Once a popular television anchor woman in Los Angeles, she has appeared in the television drama Nip/Tuck as an inspirational character who battles her disease and counsels another family who have children with ectrodactyly
Grady Stiles Sr. and Grady Stiles Jr.: known publicly as Lobster Boy and family, famous side show acts, featured on the AMC reality show, Freakshow. The Vadoma tribe in northern Zimbabwe
Mikhail Tal, Soviet chess player, World Chess Champion 1960–61
Lee Hee-ah, a Korean pianist with only two fingers on each hand. Cédric Grégoire (better known as Lord Lokhraed) is the guitarist and lead vocalist of French black metal band Nocturnal Depression and has ectrodactyly on his fretting hand, which has only two fingers. Black Scorpion, freak show performer. Sam Schröder, 2020 US Open Quad Champion. Francesca Jones, British pro tennis player, former #149 in WTA rankings. Other animals
Ectrodactyly is not only a genetic characteristic in humans, but can also occur in frogs and toads, mice,  salamanders, cows, chickens, rabbits, marmosets, cats and dogs, and even West Indian manatees. The following examples are studies showing the natural occurrence of ectrodactyly in animals, without the disease being reproduced and tested in a laboratory. In all three examples we see how rare the actual occurrence of ectrodactyly is.