This condition is also known as Karsch-Neugebauer syndrome.
Ectrodactyly or hand malformation / foot fracture, by strict definition; It is the congenital absence of the central fingers of the extremities.
The term ectrodactyly originates from the Greek words Ektroma (abortion) and daktylos (finger). Ectrodactyly was first documented in 1770 among a tribe of Guiana Indians.
Von Walter described the crab claw deformity in 1829, and Cruveilhier first used the term “lobster claw” in 1842.
Split hand or split foot malformation is a rare congenital deformity of the hand or foot, in which the middle digits are missing, and the hand or foot is cleft in the metacarpal-tarsal area.
The hand or foot appears like a lobster claw, hence the nickname “lobster claw deformity.”
In ectrodactyly, the basic embryologic abnormality is the inability to maintain the apical ectodermal ridge in normal function, leading to failure to differentiate the autopod (hand or foot).
Ectrodactyly occurs in two forms, either as an isolated disorder or as a component of a syndrome. Either of these two forms can be sporadic or familial, sporadic cases are becoming more and more common.
The most common inheritance pattern is autosomal dominant with reduced penetrance. Autosomal recessive and X-linked forms of transmission are less common, while other cases of ectrodactyly are caused by chromosome deletion and duplication.
Common abnormalities associated with ectrodactyly include tibial aplasia, craniofacial defects, and genitourinary abnormalities.
The ectrodactyly-ectodermal cleft syndrome (CEE) is the prototypical example of the ectrodactyly syndrome accompanied by multiple organ defects. It is defined by a triad of lips and palate of the CEE.
Ectrodactyly is relatively common in some communities in central Africa with a possible common parent. According to the literature, ectrodactyly associated with the syndrome is rare and isolated ectrodactyly is an even rarer entity.
Main symptoms of ectrodactyly
- Lobster claw hands.
- Absence of middle fingers.
- Presence of a single finger on the hand.
- Presence of only one toe.
Syndrome types are characterized by the absence of one or more median digits or rays in the presence of normal rays bordering the cleft.
The absence of both the finger and the metacarpal results in a deep V-shaped cleft that divides the hand into ulnar and radial parts.
The atypical types in which the remaining rays are also affected by a genetic disorder caused several reductions.
There is a much wider cleft formed by a defect of the metacarpals and middle fingers. A wide U-shaped slit with just a thumb and little finger remain.
Ectrodactyly alone is unlikely to affect health, it may be present alone, or it may be part of a number of birth defects.
As an embryological growth process, upper limb buds are seen as early as 5 weeks gestation.
After the period, the fingers and digital rays are fully formed gradually. Therefore, the blockage of the molecular and cellular process mentioned above between the sixth and seventh week of gestation would cause ectrodactyly.
Ectrodactyly is a hereditary circumstance and if you have a family history of ectrodactyly, genetic counseling is recommended. Tests can be done during the first few months of pregnancy to check for ectrodactyly.
Report of a case
A 9-year-old girl came to the Pedodontics Department for a routine dental checkup. She was born full term after an uncomplicated pregnancy to a 27-year-old mother and 29-year-old father.
She was the first child of unrelated and clinically normal parents. No toxicity, infections, trauma, or X-ray exposure were reported.
In addition, the physical and systemic examination were normal, except for the musculoskeletal system, which revealed cleft involving the hands and feet.
The index and middle fingers of his right hand were completely missing. Six fingers were present in the left hand, in which the 3rd and 4th fingers are tiny and the 2nd and 3rd fingers are absent on both lower extremities.
There were no problems with his psychological faculties and his academic achievements were commensurate with his chronological age.
The extraoral and intraoral soft tissue examination was normal. He had a mixed dentition with Angle’s class I molar relationship; The mandibular right primary first molar was severely damaged.
Preventive measures were performed and the first right primary molar was extracted and a space maintainer was administered.
The X-ray of the right hand revealed the absence of 2nd, 3rd phalanges and the presence of 1st, 4th, and 5th phalanges in which the 1st phalanx was bifid with joints.
In the left hand, 1st, 2nd, 4th and 5th phalanges are normal, and two phalanges are derived from 3rd metacarpal, thus giving the appearance of six fingers.
The girl has a younger brother who is about 7 years old, and he has no problem.
Ectrodactyly is a rare genetic disorder with an incidence of 1: 90,000 live births without sexual predilection.
Other syndromes associated with ectrodactyly include Carpenter syndrome, Delange syndrome, Goltz syndrome and Miller syndrome, in the case presented, the patient had no associated syndromes.
The usual presentation includes hands and feet bilaterally, cases of cleft hands and feet without other manifestations have been described but they are very rare.
Syndromes in which ectrodactyly is associated with other abnormalities can occur when two or more genes are affected by a chromosomal rearrangement. This explains the association of SHFM with other congenital anomalies in patients with deletions in 2q31 or 7q21.
In contrast, syndromic ectrodactyly can also be the result of a single genetic defect. The most common and best-known human SHFM syndrome is EEC syndrome, which is caused by missense mutations in the TP63 gene.
CEE syndrome is characterized by CEE of the lip / palate. On the contrary, only ectrodactyly was present in our patient.
In the atypical cleft hand, the middle fingers are absent, leaving only a few short radial and ulnar fingers with a shallow cleft giving a U-shaped deformity.
The thumb and little finger are usually the best developed digits in the hand. This deficiency is usually unilateral and there is rarely a family history.
Other associated abnormalities include cleft lip and palate, reduction in the number and size of the phalanges, syndactyly, polydactyly, triphalangeal thumb, scalp defect, genitourinary abnormalities with nasolacrimal duct atresia, and buphthalmos.