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At a glance

This is a congenital limb malformation involving the central rays of the hands or feet. Ectrodactyly (derived from Greek ektroma [abortion] and daktylos [finger]) refers to a situation where at least one entire digit (both metacarpal/metatarsal and phalanges) is missing. It is a nonspecific term applied to a variety of malformations. The usual presentation is the absence of the third digit that creates a cone-shaped cleft that tapers in toward the wrist and divides the hand into two parts. The resulting deformation resembles a lobster claw. Affected individuals have normal life spans and intelligence. It is important not to confound the “atypical cleft hand,” referred to as symbrachydactyly as part of the Ectrodactyly Syndrome. It is not a subtype of the Cleft Hand Syndrome.

Synonyms

SHFM; Absent Finger Syndrome; Split Hand/Split Feet Malformation; Karsch-Neugebauer Syndrome; Lobster Claw Deformity; Split-Hand/Foot Malformation; Split-Hand/Foot Deformity.

History

The literature reports that the first cleft hand was described centuries ago. Ambroise Paré is considered the first to have presented the first reference in 1575. Hartsink (1770) wrote the first report of true cleft hand. The first surgical procedure to correct the defect was performed in 1896 by Doctor Charles N. Dowed of New York City. Historically, a U-type cleft hand was also known as atypical cleft hand. Nowadays, this “atypical cleft hand” is referred to as symbrachydactyly and is not a subtype of the Cleft Hand Syndrome.

Classification

There are several classifications for Cleft Hand Syndrome, but the most used is described by Manske and Halikis. This classification is based on the first web space, which is the space between the thumb and the index (see table).

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Type Description Characteristics
I Normal Web Thumb-Index web space normal
IIA Mildly narrowed Thumb-Index web space mildly narrowed
IIB Severely narrowed web Thumb-Index web space severely narrowed
III Syndactylized web Thumb-Index rays syndactylized, web space obliterated
IV Merge web Thumb-Index ray suppressed and merge with the cleft
V Absent web Thumb elements suppressed, ulnar rays remain intact, thumb-index web space no longer present

Incidence

1:90,000 live births (typical split hand); 1:150,000 live births (atypical split hand). Split hand/split foot malformation affects males and females equally.

Genetic inheritance

Atypical forms are usually sporadic. SHFM is a heterogeneous condition caused by abnormalities at one of multiple loci. Five loci for split-hand/foot malformation have been mapped (7q21, Xq26, 10q24, 3q27, and 2q31). Typical cases (absence of central rays or deficiency of radial rays with no cleft) are usually inherited as an autosomal dominant trait with complete penetrance and variable expression. Autosomal recessive forms have been reported. SHFM3 is unique and considered “isolated” ectrodactyly that does not show a mutation of the TP63 ...

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