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KEY POINTS
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Key Points

  • Developmental malformation that consists of missing digits, a deep median cleft, and fusion of remaining digits.

  • Occurs as either a nonsyndromic split hand/foot malformation or as a syndromic condition with associated anomalies.

  • Most syndromic ectrodactylies are inherited as autosomal dominant conditions and are due to mutations in the p63 gene.

  • Incidence is 1/18,000 in newborns.

  • Fetuses with ectrodactyly should be referred for detailed fetal sonographic anatomic evaluation due to the high incidence of associated anomalies.

  • Parents should be examined by a medical geneticist to specifically rule out subtle malformations such as missing teeth.

  • Fetal karyotype is indicated.

  • Intelligence is generally normal and functional outcome of the hands is good following surgical repair.

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CONDITION
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The term ectrodactyly derives from the Greek ektroma, meaning “abortion,” and daktylos, meaning “finger.” Ectrodactyly is a human developmental malformation that consists of missing digits, a deep median cleft, and fusion of remaining digits, all of which result in clawlike extremities (Scherer et al., 1994). A central ray defect is the hallmark of the split hand and split foot malformation. This deformity was first reported in the medical literature in 1575, when Ambroise Paré described a 9-year-old boy with a right split hand and an absence deformity of the long bones of the legs (cited in Temtamy and McKusick, 1978) (Figure 103-1).

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Figure 103-1

Similarities occurring between two cases of split hand/split foot malformation in cases separated by four centuries. A. Affected infant with ectrodactyly of the right hand. B. Nine-year-old affected boy described by Ambroise Pare in 1575. (Reprinted, with permission, from Temtamy S, McKusick V. The Genetics of Hand Malformations. New York:Liss, 1978. Copyright 1978 Alan R. Liss. Reprinted, by permission, of John Wiley and Sons, Inc.)

Graphic Jump Location
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Although the common usage of the term ectrodactyly is as a descriptive term for the split hand or foot malformation, the term was actually first used in 1832 by St. Hilaire to denote “absence of fingers.” According to Temtamy and McKusick (1978), ectrodactyly refers to a specific hand deformity with a partial or total absence of the distal segments of the hand and normal proximal segments. In this broader definition, ectrodactyly may involve certain phalanges (apha-langia), only the digits (adactylia), or the full hand (acheiria). More recently, it has become clear that ectrodactyly occurs in two clinical settings–the split nonsyndromic hand/foot malformation, a single-gene defect that is transmitted as an autosomal dominant disorder in families; and the syndromic ectrodactylies that include split hand and split foot as one component of a group of anomalies, which occur in approximately 40% of cases (Czeizel et al., 1993; Evans et al., 1994).

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The syndromic ectrodactylies encompass many different conditions, such as ectrodactyly ectodermal dysplasia cleft syndrome (EEC syndrome). Many of these ...

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