American Journal of Medical Genetics 35588-589 (1990)
Letter to the Editor ~~~
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Hypoplastic Tibiae With Postaxial Polysyndactyly in Two Sibs: Further Conformation of a New Syndrome To the Editor: Recently, Al-Awadi et al. 119871described a new syndrome in a boy with hypoplastic, bowed tibiae and postaxial polysyndactyly, with 16 of his relatives of both sexes having bilateral syndactyly or postaxial polysyndactyly or both. A similarly affected sister of the proposita (IV-11) (Fig. 1) was delivered recently at term by ceasarean section. She had bilateral postaxial polysyndactyly type B in both hands, complete cutaneous syndactyly between the 4th and 5th fingers, bowing and shortness of both legs, tibial hypoplasia (Fig. 2), dimple on the anterior surface of both legs, and bilateral cutaneous syndactyly between the 2nd and 3rd toes. Neither craniofacial nor other anomalies were detected. No similar cases have been described before in the literature, although hypoplastic or absent tibiae, craniofacial anomalies, and preaxial polydactyly have been described [Salzer, 1960; Eaton and McKusick, 1969; Sakati et al., 1971; Canum et al,, 19841. Two suggestions could be raised to explain the pathogenetic mechanism of this syndrome. First, both sibs inherited 2 doses of the polysyndactyly dominant gene from both parents, although the mother did not show any signs of polysyndactyly. Variability in expressivity and penetrance in polysyndactyly is illustrated in this Received for publication J a n u a r y 27, 1989; revision received September 11, 1989.
Fig. 2. Radiograph of patient IV-11 showing tibial hypoplasia.
Fig. 1. Pedigree: @, syndactyly; @, polydactyly; 8, polysyndactyly; B, polysyndactyly + tibial hypoplasia.
0 1990 Wiley-Liss, Inc.
Letter to the Editor: New Syndrome
family [Al-Awadi et al., 19871. As a result of this homozygosity the clinical manifestations of the 2 sibs appeared more severe and were accompanied by other bone anomalies. Alternatively the genesis of these malformations may be due to homozygosity of a n autosomal recessive gene resulting from the frequent consanguineous marriages among this family and high inbreeding coefficient (0.02) in this area LAl-Awadi et al., 19851. The possibility of a coincident occurrence of a new mutation along the inherited polysyndactyly gene raised previously by AlAwadi et al. 119871is rejected now owing to the presence of 2 similarly affected sibs. In conclusion, the mode of inheritance of this clinical syndrome is still unknown, but we think that it may be due to the homozygous state of a n autosomal dominant gene. More reports and observations are needed to delineate the pathogenetic mechanism and variability of this syndrome.
589
REFERENCES Al-Awadi SA, Moussa MA, Naguib KK, Farag TI, Teebi AS, El-Khalifa MY, El-Dossary L (1985): Consanguinity among the Kuwaiti population. Clin Genet 27:483-486. Al-Awadi SA, Naguib KK, Farag TI, Teebi AS (1987): Hypoplastic tibiae with postaxial polysyndactyly: A new sominant syndrome. J Med Genet 24:369-372. Canum S, Lomeli RM, Martinez R, Carnevale A (1984):Absent tibiae, triphalangeal thumbs and polydactyly: Description of a family and prenatal diagnosis. Clin Genet 25:192-196. Eaton G, McKusick V (1969):A seemingly unique polydactyly syndactyly syndrome in four persons in three generations. In (eds):“Limb Malformations.” BD:OAS. White Plains: The National Foundation, V (3):221. Sakati N, Nyhan W, Tisdale W (1971): A new syndrome with acrocephaiopolydactyly, cardiac disease and distinctive defects of the ear, skin and lower limbs. J Pediatr 79:104-109. Salzer M (1960):Uber den Kongenitalen: Defekt Tibia. Zentralbl Chir 17:673-677.
K.K. Naguib S.A. Al-Awadi Kuwait Medical Genetics Centre Maternity Hospital Safat. Kuwait
Letter to the Editor ~~~
~
Hypoplastic Tibiae With Postaxial Polysyndactyly in Two Sibs: Further Conformation of a New Syndrome To the Editor: Recently, Al-Awadi et al. 119871described a new syndrome in a boy with hypoplastic, bowed tibiae and postaxial polysyndactyly, with 16 of his relatives of both sexes having bilateral syndactyly or postaxial polysyndactyly or both. A similarly affected sister of the proposita (IV-11) (Fig. 1) was delivered recently at term by ceasarean section. She had bilateral postaxial polysyndactyly type B in both hands, complete cutaneous syndactyly between the 4th and 5th fingers, bowing and shortness of both legs, tibial hypoplasia (Fig. 2), dimple on the anterior surface of both legs, and bilateral cutaneous syndactyly between the 2nd and 3rd toes. Neither craniofacial nor other anomalies were detected. No similar cases have been described before in the literature, although hypoplastic or absent tibiae, craniofacial anomalies, and preaxial polydactyly have been described [Salzer, 1960; Eaton and McKusick, 1969; Sakati et al., 1971; Canum et al,, 19841. Two suggestions could be raised to explain the pathogenetic mechanism of this syndrome. First, both sibs inherited 2 doses of the polysyndactyly dominant gene from both parents, although the mother did not show any signs of polysyndactyly. Variability in expressivity and penetrance in polysyndactyly is illustrated in this Received for publication J a n u a r y 27, 1989; revision received September 11, 1989.
Fig. 2. Radiograph of patient IV-11 showing tibial hypoplasia.
Fig. 1. Pedigree: @, syndactyly; @, polydactyly; 8, polysyndactyly; B, polysyndactyly + tibial hypoplasia.
0 1990 Wiley-Liss, Inc.
Letter to the Editor: New Syndrome
family [Al-Awadi et al., 19871. As a result of this homozygosity the clinical manifestations of the 2 sibs appeared more severe and were accompanied by other bone anomalies. Alternatively the genesis of these malformations may be due to homozygosity of a n autosomal recessive gene resulting from the frequent consanguineous marriages among this family and high inbreeding coefficient (0.02) in this area LAl-Awadi et al., 19851. The possibility of a coincident occurrence of a new mutation along the inherited polysyndactyly gene raised previously by AlAwadi et al. 119871is rejected now owing to the presence of 2 similarly affected sibs. In conclusion, the mode of inheritance of this clinical syndrome is still unknown, but we think that it may be due to the homozygous state of a n autosomal dominant gene. More reports and observations are needed to delineate the pathogenetic mechanism and variability of this syndrome.
589
REFERENCES Al-Awadi SA, Moussa MA, Naguib KK, Farag TI, Teebi AS, El-Khalifa MY, El-Dossary L (1985): Consanguinity among the Kuwaiti population. Clin Genet 27:483-486. Al-Awadi SA, Naguib KK, Farag TI, Teebi AS (1987): Hypoplastic tibiae with postaxial polysyndactyly: A new sominant syndrome. J Med Genet 24:369-372. Canum S, Lomeli RM, Martinez R, Carnevale A (1984):Absent tibiae, triphalangeal thumbs and polydactyly: Description of a family and prenatal diagnosis. Clin Genet 25:192-196. Eaton G, McKusick V (1969):A seemingly unique polydactyly syndactyly syndrome in four persons in three generations. In (eds):“Limb Malformations.” BD:OAS. White Plains: The National Foundation, V (3):221. Sakati N, Nyhan W, Tisdale W (1971): A new syndrome with acrocephaiopolydactyly, cardiac disease and distinctive defects of the ear, skin and lower limbs. J Pediatr 79:104-109. Salzer M (1960):Uber den Kongenitalen: Defekt Tibia. Zentralbl Chir 17:673-677.
K.K. Naguib S.A. Al-Awadi Kuwait Medical Genetics Centre Maternity Hospital Safat. Kuwait
