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).

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).

The syndromic ectrodactylies encompass many different conditions, such as ectrodactyly ectodermal dysplasia cleft syndrome (EEC syndrome). Many of these syndromic ectrodactylies are due to mutations in the p63 gene (Brunner et al., 2002). P63 is specifically expressed in embryonic ectoderm. The p63 knockout mouse dies at birth and has absent epidermis, prostate, breast, and urothelial tissues as well as limb anomalies.

The incidence of split hand malformation is 1 in 18,000 newborns (Czeizel et al., 1993; Evans et al., 1994)

The characteristic sonographic findings in ectrodactyly are the absence of the central digits of the hand with normal or enlarged digits at the lateral aspects (Figure 103-2) (Leung et al., 1995). Prenatal diagnosis of ectrodactyly was first reported in 1980, when a fetus studied at 16 and 19 weeks of gestation was noted to have one hand with syndactyly and both feet with lobster-claw deformities. This diagnosis occurred in the setting of a father known to be affected with ectrodactyly. These parents elected to terminate the pregnancy. Examination following termination confirmed bilateral syndactyly of the third and fourth fingers and bilateral lobster-claw deformities of the feet (Henrion et al., 1980). Kohler et al. (1989) described the detection of a 30-week appropriate-for-gestational-age male fetus with cleft palate, syndactyly, and lobster-claw deformity and no family history of ectrodactyly.

Transvaginal sonography has also been used to diagnose bilateral cleft lip with lobster-claw deformities of the hands and feet in a fetus with an apparently negative family history at 14 weeks of gestation (Figure 103-3). Post-termination studies confirmed the diagnosis of EEC syndrome. The mother was a healthy 24-year-old woman who had sonography performed as an anatomic screen without a specific clinical indication. After diagnosis of EEC syndrome in this fetus, the mother was more closely examined and was found to have microdontia of two lateral upper incisors. This was not apparent initially because cosmetic dental work had been performed. The authors suggested that the dental anomalies could represent an extremely mild form of EEC syndrome in the mother. She was advised to have transvaginal sonography after the 10th week of gestation in a subsequent pregnancy, when fetal fingers and toes can be visualized (Bronshtein and Gershoni-Baruch, 1993). Approximately 8% of patients with EEC syndrome also have urologic anomalies. Chuangsuwanich et al. (2005) described a fetus with EEC and a large nephrogenic cyst that resulted in bladder and pulmonary hypoplasia.

We described a case of ectrodactyly in all four fetal extremities observed on a sonogram performed for assessment of pre-eclampsia at 33 4/7 weeks (O’Brien et al., 2002). The father of the fetus had bilateral foot and right hand ectrodactyly, small peg-shaped teeth, microretrognathia, nail dysplasia, and a history of lacrimal duct blockage requiring surgery during his infancy. This prompted a diagnosis of acro-dermato-ungual-lacrimal-tooth (ADULT) syndrome, a dominantly inherited condition. Remarkably, the father had never been seen by a geneticist, and was told by his primary care physician that his condition would not affect his offspring. Following publication of the sonographic findings (O’Brien et al., 2002) the father and son were shown to have mutations in the p63 gene.

Ectrodactyly has also been described in association with autosomal recessively inherited disorders, such as Smith–Lemli–Opitz syndrome (de Jong et al., 1998), bilateral tibial agenesis with ectrodactyly (Witters et al., 2001), and acro-cardio-facial syndrome (Guion-Almeida et al., 2000).

The main consideration in the prenatal diagnosis of ectrodactyly is the distinction between the nonsyndromic split hand and foot malformation, inherited asa single-gene autosomal dominant disorder, versus the syndromic ectrodactylies. Some of the clinical features of the various ectrodactyly syndromes are described in Table 103-1. The most well known of the syndromic ectrodactylies is the EEC syndrome (ec trodactyly, ectodermal dysplasia, cleft lip and palate). In the EEC syndrome, the ectodermal dysplasia is manifested by lightly pigmented, sparse and wiry hair, a decreased number of hairs in the eyelashes and eyebrows, hypopigmented skin with numerous pigmented nevi in the head and neck region, abnormalities of the primary and permanent teeth, including hypoplasia of the enamel, severe caries, brittle or dystrophic nails, atretic lacrimal puncta, a decrease or absence of the orifices of the meibomian glands, and corneal vascularization and scarring, which results in limitation of visual acuity or functional blindness (Bystrom et al., 1975). A conductive sensorineural hearing loss may be a complication of the cleft palate seen in EEC syndrome (Anneren et al., 1991). In one large study of 123 affected patients, 100% had ectodermal dysplasia, 84% had tear duct anomalies, 83.7% had ectrodactyly, 72.4% had cleft lip and/or palate, 33.3% had genitourinary anomalies, and 14% had deafness (Rodini and Richieri-Costa, 1990). EEC syndrome is characterized by variability in clinical expression. A variety of other disorders overlap the EEC syndrome.