*185900 SYNDACTYLY, TYPE I
Alternative
titles; symbols
ZYGODACTYLY
table OF
CONTENTS
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TEXT
From the medical literature and from their own
experience, Temtamy and
McKusick (1978) concluded that there are at
least 5 phenotypically different types of
syndactyly involving the hands, with or without
foot involvement. All are inherited as autosomal
dominant traits and within any pedigree there is
uniformity of type of syndactyly, allowing for the
variation characteristic for dominant traits. These
genetic types of syndactyly have to be
differentiated from syndactyly associated with
congenital bands for which there is no evidence of
a genetic basis. In this common type of syndactyly,
sometimes called zygodactyly, there is usually
complete or partial webbing between the 3rd and 4th
fingers which is occasionally associated with
fusion of the distal phalanges of these fingers.
Other fingers are sometimes also involved but the
3rd and 4th fingers are the most commonly affected.
In the feet there is usually complete or partial
webbing between the 2nd and 3rd toes. Sometimes
only the hands are affected and sometimes only the
feet. Lueken (1938)
reported this type of syndactyly in 18 males and 29
females of 5 generations illustrating the various
degrees of expressivity of the same gene. Schofield
(1921) presented a pedigree that suggested
holandric inheritance to Castle
(1922). Stern (1957)
was unable, however, to obtain further evidence of
same and suggested that inheritance is autosomal
dominant. Straus (1926)
supported the latter mode of inheritance. Hsu
(1965) described bilateral syndactyly in 6
generations of a Chinese family. Of the 31
descendants of one syndactylous woman, 22 were
affected. Skin and bony fusion of the distal
phalanges of the third, fourth and fifth fingers
were present. At least one person also showed union
of the third, fourth and fifth toes. In a
collaborative Latin-American study, Castilla
et al. (1980) reported an incidence of
syndactyly (without other associated limb
anomalies, Poland complex or amniotic bands) in 174
of 599,109 consecutive newborn infants (3 per
10,000). In 133, syndactyly was the only diagnosed
anomaly. The most common type was isolated
syndactyly of toes 2 and 3 (70 cases); it affected
more males than females and had a higher than
expected frequency in infants of white
non-Latin-European ancestry. The second most
frequent form was isolated syndactyly of fingers 3
and 4 (18 cases), and the third was isolated
syndactyly of toes 4 and 5 (13 cases). All three
fall into the category of type I syndactyly, or
zygodactyly.
The Temtamy and McKusick
(1978) classification of isolated, nonsyndromic
polydactyly and syndactyly was based on a logical
anatomic approach. As pointed out by Winter
and Tickle (1993), considerable advances in the
molecular embryology of the developing limb bud may
adumbrate a molecular classification. These
advances include the proposal that retinoic acid
and/or related retinoids are the morphogens
responsible for the morphogenetic gradient giving
rise to anterior-posterior pattern formation of the
limb bud, the suggestion that the HOX4 complex and
other homeotic genes are involved in patterning,
and a greater understanding of other mechanisms
such as programmed cell death (apoptosis) in the
shaping of the final hand and foot.
Percin et al. (1998)
described a large inbred Turkish pedigree with
syndactyly type I. Three individuals born to
first-cousin affected parents were found to have a
particularly severe form of mesoaxial syndactyly,
the characteristic features of which were complete
syndactyly and synostosis of the third and fourth
fingers with severe bone reduction in the proximal
phalanges; hypoplasia of the thumbs and halluces;
aplasia/hypoplasia of the middle phalanges of the
second and fifth fingers; and complete or partial
soft tissue syndactyly of the toes. Percin
et al. (1998) suggested that the severe nature
of the clinical phenotype in these individuals may
be the result of homozygosity for syndactyly type
I. SSCP and linkage analysis indicated that neither
HOXD13 nor other relevant genes at 2q31 was
responsible for this phenotype.
REFERENCES
- 1. Castilla, E. E.;
Paz, J. E.; Orioli-Parreiras, I. M. :
- Syndactyly: frequency of specific
types. Am. J. Med. Genet. 5:
357-364, 1980.
PubMed ID : 6249121
- 2. Castle, W. E.
:
- The Y-chromosome type of sex-linked
inheritance in man. Science
55: 703-704, 1922.
- 3. Hsu, C.-K. :
- Hereditary syndactylia in a Chinese
family. Chinese Med. J. 84:
482-485, 1965.
PubMed ID : 5865199
- 4. Lueken, K. G.
:
- Ueber eine Familie mit
Syndaktylie. Z. Menschl. Vererb.
Konstitutionsl. 22: 152-159, 1938.
- 5. Percin, E. F.;
Percin, S.; Egilmez, H.; Sezgin, I.; Ozbas, F.;
Akarsu, A. N. :
- Mesoaxial complete syndactyly and
synostosis with hypoplastic thumbs: an unusual
combination or homozygous expression of
syndactyly type I? J. Med.
Genet. 35: 868-874, 1998.
PubMed ID : 9783716
- 6. Schofield, R.
:
- Inheritance of webbed toes.
J. Hered. 12: 400-401, 1921.
- 7. Stern, C. :
- The problem of complete Y-linkage in
man. Am. J. Hum. Genet. 9:
147-166, 1957.
- 8. Straus, W. L.,
Jr. :
- The nature and inheritance of webbed
toes in man. J. Morph. 41:
427-439, 1926.
- 9. Temtamy, S. A.;
McKusick, V. A. :
- The Genetics of Hand
Malformations. New York: Alan R. Liss
(pub.) 1978.
- 10. Winter, R. M.;
Tickle, C. :
- Syndactylies and polydactylies:
embryological overview and suggested
classification. Europ. J. Hum.
Genet. 1: 96-104, 1993.
CLINICAL
SYNOPSIS
View
Clinical Synopsis Entry
Michael J. Wright - updated : 11/9/1998
CREATION DATE
Victor A. McKusick : 6/2/1986
EDIT HISTORY
alopez : 12/11/1998
terry : 11/9/1998
mimadm : 5/10/1995
davew : 6/9/1994
carol : 12/31/1992
carol : 12/16/1992
supermim : 3/16/1992
supermim : 3/20/1990
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