Split-hand/split-foot malformation (SHFM) is a limb malformation involving the central rays of the autopod and presenting with syndactyly, median clefts of the hands and feet, and aplasia and/or hypoplasia of the phalanges, metacarpals, and metatarsals. Some patients with ... Split-hand/split-foot malformation (SHFM) is a limb malformation involving the central rays of the autopod and presenting with syndactyly, median clefts of the hands and feet, and aplasia and/or hypoplasia of the phalanges, metacarpals, and metatarsals. Some patients with SHFM1 have been found to have mental retardation, ectodermal and craniofacial findings, orofacial clefting (Elliott and Evans, 2006), and neurosensory hearing loss (Tackels-Horne et al., 2001). - Genetic Heterogeneity of Split-hand/Split-foot Malformation Additional SHFM loci include SHFM2 (313350) on chromosome Xq26; SHFM3 (246560), caused by duplication of chromosome 10q24; SHFM4, caused by mutation in the TP63 gene (603273) on chromosome 3q27; SHFM5 (606708) on chromosome 2q31; and SHFM6 (225300), caused by mutation in the WNT10B gene (601906) on chromosome 12q13. Also see SHFM1D (220600) for a form of SHFM1 with deafness that may be caused by homozygous mutation in the DLX5 gene (600028).
The term ectrodactyly is derived from Greek ektroma (abortion) and daktylos (finger). It is a nonspecific term applied to a variety of malformations and is probably best reserved for transverse terminal aphalangia, adactylia, or acheiria. Cases defined in ... The term ectrodactyly is derived from Greek ektroma (abortion) and daktylos (finger). It is a nonspecific term applied to a variety of malformations and is probably best reserved for transverse terminal aphalangia, adactylia, or acheiria. Cases defined in this way are usually sporadic. As a rule, one hand is involved and the feet are not affected. Congenital constriction rings ('amniotic bands') are sometimes associated. Many cases described as examples of autosomal dominant inheritance of ectrodactyly are in fact type B brachydactyly (113000) (Temtamy and McKusick, 1978). The anomaly here called split-hand deformity is also termed ectrodactyly. Birch-Jensen (1949) recognized 2 anatomic types: typical 'lobster claw' and monodactyly. The anatomic classification has no genetic significance because either type may occur in the same family or on different limbs of the same person (Temtamy and McKusick, 1978). Absence of the central rays characterized the first anatomic type. The hand is divided into 2 parts by a cone-shaped cleft tapering proximally. The 2 parts of the hand can be apposed like a lobster claw. A comparable deformity of the feet may be present. In the second anatomic type, or monodactyly, the radial rays are absent with, as a rule, only the fifth digit remaining. Vogel (1958) suggested that 2 varieties of split-hand deformity exist: (1) a type with constant involvement of the feet and regular autosomal dominant inheritance, and (2) a type with inconsistent involvement of the feet and irregular inheritance. Viljoen and Beighton (1984) studied this anomaly in a remote African village. Lay reports of an 'ostrich-footed' tribe had appeared in the past. Lewis (1912), subsequently Sir Thomas Lewis and a noted cardiologist, gave one of the earliest and clearest descriptions of a kindred with split-hand/split-foot. Tackels-Horne et al. (2001) described 2 families with a form of SHFM in which deficiency of the central rays in the appendicular skeleton was associated with sensorineural hearing loss. In 1 family, variably expressed split-foot malformations were found in 6 of 11 presumed gene carriers, and mild to moderate sensorineural hearing loss in 4. Split-hand and cleft lip/palate in 1 individual and tibial deficiency in another suggested that these manifestations are uncommon components of the syndrome. There were no ectodermal abnormalities. In the other family, variable split-foot was observed in 3 of 4 gene carriers, and sensorineural deafness was present in 3. Split-hand was seen only in a gene carrier who also had split-foot and deafness. One gene carrier had only deafness. Haberlandt et al. (2001) reported an 18-month-old boy, born of fourth-cousin Austrian parents, who had ectrodactyly of the right foot associated with conductive and profound sensorineural deafness and inner and middle ear malformations. Evaluation at 15 months of age due to failure to thrive revealed weight, length, and head circumference all below the 3rd centile; he also had arched eyebrows, a small triangular nose with depressed nasal bridge, hypertelorism, hypopigmented retina, large biparietal diameter, overfolded helices of ears with attached earlobes, micrognathia, submucous cleft palate, carious primary teeth and hypodontia, sparse light-colored hair, pale skin, cryptorchidism, and bilateral severe congenital vertical talus. In addition, psychomotor developmental delay was noted. CT and MRI scans revealed Mondini dysplasia of the inner ear, and cochlear implanting showed fixation of the ossicular chain. Wieland et al. (2004) reported a 4-year-old boy with typical 'lobster claw' ectrodactyly of the left hand and both feet, with syndactyly of the third and fourth digits of the right hand, who also had dysplastic ears, retrognathia, and profound deafness with Mondini dysplasia of the inner ear on MRI. Psychomotor development was normal.
Roberts and Tabin (1994) reviewed the events of early limb development, which are similar for all tetrapods in that they define patterning in both the proximal/distal, i.e., humerus to digits, and the anterior/posterior, i.e., first to fifth digits, ... Roberts and Tabin (1994) reviewed the events of early limb development, which are similar for all tetrapods in that they define patterning in both the proximal/distal, i.e., humerus to digits, and the anterior/posterior, i.e., first to fifth digits, orientations. Most of the now classic embryologic experiments that defined limb patterning were performed in the chick. Roberts and Tabin (1994) listed 7 candidate genes for human limb-development defects. Duijf et al. (2003) reviewed the molecular genetics of split-hand/foot malformation in man and mouse.