Mesoaxial complete syndactyly and synostosis with hypoplastic thumbs: an unusual combination or homozygous expression of syndactyly type I?

Syndactyly type I is an autosomal dominant condition with complete or partial webbing between the third and fourth fingers or the second and third toes or both. We report here a previously undescribed phenotype of severe mesoaxial syndactyly and synostosis in patients born to affected parents. The characteristic features of these severe cases are (1) complete syndactyly and synostosis of the third and fourth fingers; (2) severe bone reduction in the proximal phalanges of the same fingers; (3) hypoplasia of the thumbs and halluces; (4) aplasia/hypoplasia of the middle phalanges of the second and fifth fingers; and (5) complete or partial soft tissue syndactyly of the toes. We report on three offspring with this phenotype from two different branches of a syndactyly type I family, suggesting that they may be homozygous for this condition. SSCP and linkage analysis indicated that neither HOXD13 nor other relevant genes in the chromosome 2q31 region was responsible for this phenotype.     

Cenani–Lenz syndrome restricted to limb and kidney anomalies associated with a novel LRP4 missense mutation

Cenani–Lenz syndrome (CLS) is a rare autosomal recessive developmental disorder of the limbs. The disorder is characterized by complete syndactyly with metacarpal fusions and/or oligodactyly sometimes accompanied by radioulnar synostosis. The clinical expression is variable and kidney agenesis/hypoplasia, craniofacial dysmorphism and teeth abnormalities are frequent features as well as lower limb involvement. CLS was recently associated with mutations in the low-density lipoprotein receptor-related protein 4 (LRP4) gene and dysregulated canonical WNT signaling. We have identified a large consanguineous Pakistani pedigree with 9 members affected by CLS. The affected individuals present with a consistent expression of the syndrome restricted to the limbs and kidneys. Symptoms from the lower limb are mild or absent and there were no radioulnar synostosis or craniofacial involvement. Genetic analysis using autozygosity mapping and sequencing revealed homozygosity for a novel missense mutation c.2858T > C (p.L953P) in the LRP4 gene. The mutation is located in a region encoding the highly conserved low-density lipoprotein receptor repeat class B domain of LRP4. Our findings add to the genotype–phenotype correlations in CLS and support kidney anomalies as a frequent associated feature.     

Mutations in the fourth β‐propeller domain of LRP4 are associated with isolated syndactyly with fusion of the third and fourth fingers

Isolated hand syndactyly is a common limb malformation with limited known genetic etiology. We used exome sequencing to discover two novel variants, chr11 g.46896373C>G; p.D1403H and chr11 g.46893078G>T; p.Q1564K, in LRP4 in a child with isolated bilateral syndactyly of the third and fourth fingers. Each variant was inherited from a different parent and neither parent was affected. Variants in LRP4 have been previously associated with syndactyly in Cenani‐Lenz syndactyly syndrome and Sclerosteosis 2, but have not been reported in individuals with isolated syndactyly. LRP4 inhibits LRP6/LRP5‐mediated activation of canonical Wnt signaling and mediates sclerostin‐dependent inhibition of bone formation. p.D1403H and p.Q1564K are located within the fourth β‐propeller of the extracellular protein domain that has yet to be associated with human disease. Functional analyses of p.D1403H and p.Q1564K show that they significantly decrease LRP4's inhibition of Wnt signaling. These results suggest that variants in the fourth β‐propeller of the extracellular protein domain may cause a phenotype distinct from previously characterized LRP4 variants.     

Autosomal recessive mesoaxial synostotic syndactyly with phalangeal reduction maps to chromosome 17p13.3

Previously we have described a novel and distinct form of non-syndromic osseous syndactyly segregating in an autosomal recessive pattern in a consanguineous Pakistani family. The limb findings include mesoaxial reduction of the fingers, synostoses of the third and fourth metacarpals with associated single phalanges, fifth finger clinodactyly, and preaxial webbing of toes. We identified another published report of this phenotype in a large, inbred Turkish family. In the present study we mapped the phenotype in the Pakistani and Turkish families to chromosome 17p13.3 (multipoint LOD score 5.1). The identification of a single locus for this complex limb malformation in two families with distinct ethnic backgrounds supports the hypothesis that this is a distinct form of syndactyly. Since this form of syndactyly is phenotypically distinct from the previously described eight types, we propose to name this phenotype mesoaxial synostotic syndactyly with phalangeal reduction (MSSD, type IX syndactyly, Malik-Percin type).     

Craniodigital syndromes: Report of a child with Filippi syndrome and discussion of differential diagnosis

We describe a boy with low birth weight, congenital microcephaly, multiple minor facial anomalies, cleft palate, soft tissue syndactyly of fingers and toes, and moderate to severe mental retardation. Literature review suggested 6 possible diagnoses, including Scott craniodigital syndrome, Chitayat syndrome, Filippi syndrome, Zerres syndrome, Kelly syndrome, and Woods syndrome. Each has as part of the phenotype craniofacial anomalies and soft tissue syndactyly of fingers and toes; and superficially, distinction among the 6 may be difficult. However, based on the phenotype analysis we performed, we conclude that our patient has Filippi syndrome, and thus is the first reported case from the United States. © 1995 Wiley-Liss, Inc.     

Unknown syndrome: nasal hypoplasia, sparse hair, truncal obesity, genital hypoplasia, and severe mental retardation.

A 4 year old girl is described with severe mental retardation, peculiar face with nasal hypoplasia, sparse hair, genital hypoplasia, truncal obesity, puffy hands, and small feet with complete cutaneous syndactyly of the second and third toes.     

Unknown syndrome: ischiadic hypoplasia, renal dysfunction, immunodeficiency, and a pattern of minor congenital anomalies.

We report a 6 year old male with a pattern of malformations and anomalies including intrauterine growth retardation, microcephaly, psychomotor retardation, a pattern of craniofacial anomalies (flat face, hypertelorism, epicanthic folds, strabismus, short nose, low set ears), hypospadias and cryptorchidism, bilateral partial cutaneous syndactyly between fingers 2 to 5 and toes 2 to 4, postaxial polydactyly of the fingers and toes, severe conductive hearing loss, hypoplasia of the ischiadic bones, complex renal dysfunction, hypogammaglobulinaemia with proneness to bacterial infections of the upper and lower respiratory tract, and recurrent pseudomembranous enterocolitis. The parents are cousins of Turkish origin.     

A novel insertion mutation in the cartilage-derived morphogenetic protein-1 (<Emphasis Type="Italic">CDMP1</Emphasis>) gene underlies Grebe-type chondrodysplasia in a consanguineous Pakistani family

Background  

Grebe-type chondrodysplasia (GCD) is a rare autosomal recessive syndrome characterized by severe acromesomelic limb shortness with non-functional knob like fingers resembling toes. Mutations in the cartilage-derived morphogenetic protein 1 (CDMP1) gene cause Grebe-type chondrodysplasia.     

A case of Pfeiffer syndrome

Pfeiffer Syndrome is as rare as Apert syndrome in the Western population. This condition is very rare in the Asian population and has not been previously reported in Korea. The authors report with a review of literature the case of a newborn baby with Pfeiffer syndrome, manifested by bicoronal craniosynostosis, broad thumbs, and big toes. The infant also had bilateral syndactyly of the fingers and toes, mild proptosis, choanal hypoplasia and maxillary hypoplasia.     

Complex toe syndactyly with characteristic facial phenotype: a new syndrome?

Nonsyndromic syndactyly is a common, heterogeneous hereditary condition of webbed fingers and toes that can be cutaneous or bony, unilateral or bilateral. We describe a patient with complex toe syndactyly and oligodactyly, some interesting skeletal hand findings and atypical facial features without other case like this described before. Cenani-Lenz syndrome (CLS) is a rare disorder with total syndactyly and irregular synostosis of carpal, metacarpal and phalanges, it may involve ulna and radius and digital rays may be absent, some of these were described with atypical facial features and one patient had renal hypoplasia and vertebral anomalies but our patient does not have the oligodactyly or syndactyly of the hands that is consistently present in all patients with CLS. The atypical facial features of our patient resemble Kabuki syndrome but oligodactyly and complex syndactyly have not been described in Kabuki syndrome and this patient has normal intelligence, and extreme eyelid defect (resembling ablepharon). Therefore, for our patient, we suggested to treat in a new condition of limb anomalies and atypical face.     

Oculo-dento-digital dysplasia: Lack of genotype–phenotype correlation for GJA1 mutations and usefulness of neuro-imaging

Oculo-dento-digital dysplasia (ODDD) is an autosomal dominant disorder with complete penetrance and high intra- and interfamilial phenotypic variability. The key features in this syndrome are microphthalmia, enamel hypoplasia and syndactyly of the 4th–5th fingers. ODDD is caused by mutations in the connexin 43 gene (GJA1). We report here four patients from three families with GJA1 mutations, one of them diagnosed prenatally. The three mutations (c.52T > C/p.Ser18Pro, c.689_690delTA/p.Tyr230CysfsX6, c.442C > G/p.Arg148Gly) have been reported once before. Two patients had white matter hypersignal anomalies, associated in one case with mental retardation, but asymptomatic in the other one, an observation that leads us to discuss systematic neuroradiological imaging for ODDD. One case has optic atrophy, another has hypospadias. The patient carrying a truncating mutation of Cx43 did not have palmoplantar keratoderma, in contradiction with the previously suggested genotype–phenotype correlation between truncating mutation and skin involvement.     

Scalp-ear-nipple syndrome: Additional manifestations

Scalp-ear-nipple (SEN) syndrome is a rare, autosomal dominant condition that causes aplasia cutis congenita of the scalp, alteration of the shape of the external ear, and hypoplasia of the nipple. Women in a new family, the fifth to be described, had virtually complete aplasia of the breast and a small skin dimple without any pigmentation instead of a normal nipple, although other affected women had normal breast and nipple development. Dental changes included widely spaced or missing secondary teeth; the ears were cupped or folded and stood out from the head, axillary apocrine secretion and axillary hair growth were reduced; and finger nails were brittle. There was no generalized abnormality of sweating. Some patients had partial syndactyly of the 3rd and 4th fingers, and complete cutaneous syndactyly of the 2nd and 3rd toes. © 1994 Wiley-Liss, Inc.     

Distinct phenotype of PHF6 deletions in females

We report on two female patients carrying small overlapping Xq26.2 deletions of 100 kb and 270 kb involving the PHF6 gene. Mutations in PHF6 have been reported in individuals with Borjeson–Forssman–Lehmann syndrome, a condition present almost exclusively in males. Two very recent papers revealed de novo PHF6 defects in seven female patients with intellectual disability and a phenotype resembling Coffin–Siris syndrome (sparse hair, bitemporal narrowing, arched eyebrows, synophrys, high nasal root, bulbous nasal tip, marked clinodactyly with the hypoplastic terminal phalanges of the fifth fingers and cutaneous syndactyly of the toes, Blaschkoid linear skin hyperpigmentation, dental anomalies and occasional major malformations). The clinical presentation of these patients overlaps completely with our first patient, who carries a germline deletion involving PHF6. The second patient has a mosaic deletion and presented with a very mild phenotype of PHF6 loss in females. Our report confirms that PHF6 loss in females results in a recognizable phenotype overlapping with Coffin–Siris syndrome and distinct from Borjeson–Forssman–Lehmann syndrome. We expand the clinical spectrum and provide the first summary of the recommended medical evaluation.     

A novel ZRS mutation in a Balochi tribal family with triphalangeal thumb, pre-axial polydactyly, post-axial polydactyly, and syndactyly

Limb malformations are one of the most common types of human congenital malformations. Mutations in the ZRS enhancer of Sonic Hedgehog are thought to be responsible for pre-axial polydactyly in multiple independent families. Here, we describe a large Balochi tribal family from Southern Punjab, Pakistan, with a variable set of limb malformations and a novel ZRS mutation. The family has a limb phenotype characterized by triphalangeal thumb, pre-axial polydactyly, and post-axial polydactyly. There is also a high degree of phenotypic heterogeneity with less common clinical findings in the affected family members that include osseous syndactyly of forth-fifth fingers, clinodactyly, hypoplasia of mesoaxial fingers, and bifid halluces. The presentation in most of the affected patients was bilateral and symmetrical. A heterozygous C>A mutation at position 287 of the ZRS enhancer (chr7:156,584,283; hg19) was detected in all affected subjects and is absent from four unaffected family members, 42 unrelated samples, and multiple databases of human variation. Combined, these results identify a novel ZRS287 C>A mutation which leads to a variable spectrum of limb phenotypes.     

A novel frameshift variant in BHLHA9 underlies mesoaxial synostotic syndactyly associated with postaxial polydactyly

Mesoaxial synostotic syndactyly (MSSD) with phalangeal reduction is an uncommon congenital limb abnormality characterized by central osseous synostosis at a metacarpal level, mesoaxial reduction of the fingers, and preaxial cutaneous syndactyly in toes. In rare cases, the disease is also associated with fifth finger clinodactyly and postaxial polydactyly. It has autosomal recessive inheritance pattern caused by homozygous variants in the gene BHLHA9 mapped at chromosome 17p13.3.In the present study, a consanguineous family of Pakistani origin segregating MSSD in autosomal recessive form was characterized at clinical and genetic levels. Clinically, the diseased individuals have MSSD associated with clinodactyly and polydactyly. Homozygosity mapping followed by Sanger sequencing of BHLHA9 revealed a novel frameshift variant NM_001164405.1: c.409-409delC; p.(His137Thrfs*61) segregating with the disease phenotypes in the family.This is the second report providing evidence of association of polydactyly with MSSD caused by frameshift variant in the gene BHLHA9. The present molecular investigation will support genetic counselling of the local population carrying diseased variants.     

Syndactyly: phenotypes, genetics and current classification

Syndactyly is one of the most common hereditary limb malformations depicting the fusion of certain fingers and/or toes. It may occur as an isolated entity or a component of more than 300 syndromic anomalies. Syndactylies exhibit great inter- and intra-familial clinical variability. Even within a subject, phenotype can be unilateral or bilateral and symmetrical or asymmetrical. At least nine non-syndromic syndactylies with additional sub-types have been characterized. Most of the syndactyly types are inherited as autosomal dominant but two autosomal recessive and an X-linked recessive entity have also been described. Whereas the underlying genes/mutations for types II-1, III, IV, V, and VII have been worked out, the etiology and molecular basis of the other syndactyly types remain unknown. In this communication, based on an overview of well-characterized isolated syndactylies, their cardinal phenotypes, inheritance patterns, and clinical and genetic heterogeneities, a 'current classification scheme' is presented. Despite considerable progress in the understanding of syndactyly at clinical and molecular levels, fundamental questions regarding the disturbed developmental mechanisms leading to fused digits, remain to be answered.     

Gorlin-Chaudhry-Moss or Saethre-Chotzen syndrome?

We report a 2-year-old girl with craniosynostosis, an ossification defect of the cranial vault, midface hypoplasia, low frontal hairline, anti-mongoloid slant of the palpebral fissures, ptosis of the lateral upper lids and high-arched narrow palate. There are additional findings fitting the Gorlin-Chaudhry-Moss syndrome, such as hypoplasia of the labia majora, hypoplasia of the distal phalanges of fingers and toes and conductive hearing loss, but hypertrichosis and dental anomalies are missing, which were described in the four females previously reported with the probably autosomal recessive Gorlin-Chaudhry-Moss syndrome. Since the autosomal dominant Saethre-Chotzen syndrome may show similar craniofacial features, short fingers with non-obligatory cutaneous syndactyly, and ossification defects of the cranial vault, the Saethre-Chotzen syndrome should also be considered in our patient.     

Syndactyly type V

We report a mother and three of her four children with type V syndactyly. All the patients had metacarpal 4–5 fusion. The other hand anomalies consisted of abnormal origin of the fifth fingers, anomalies of digits 4 and 5, brachydactyly, syndactyly, camptodactyly, absent distal interphalangeal creases, and unusual palmar dermatoglyphics. Anomalies of the feet consisted of varus deviation of the metatarsals, valgus deviation of the toes, hyperplasia of the first ray, and hypoplasia of the third to fifth rays. None of the patients had metatarsal fusions. The anomalies were similar in the mother and her two older sons far less severe in her daughter. This daughter also had a congenital anomaly of the urinary tract. Anomalous and/or defective muscle and tendon insertions were demonstrated in one patient during an operation. Syndactyly V is transmitted as an autosomal dominant trait.     

Complex postaxial polydactyly types A and B with camptodactyly,hypoplastic third toe,zygodactyly and other digit anomalies caused by a novel GLI3 mutation

Polydactyly is a phenotypically and genetically highly heterogeneous limb malformation with preaxial and postaxial subtypes and subtypes A and B. Most polydactyly entities are associated with GLI3 mutation. We report on 10 affected individuals from a large Pakistani kindred initially evaluated as a possible new condition. The phenotype is postaxial polydactyly types A and B associated with zygodactyly, postaxial webbing of toes and additional features not previously reported for isolated polydactyly such as camptodactyly, hypoplasia of third toe, and wide space between hallux and second toe. Hypothesizing that the disorder could have resulted from a mutation in a novel gene responsible for polydactyly, we launched a genetic investigation. By linkage mapping and exome sequencing in the most severe case, we identified novel heterozygous frameshift mutation NM_000168.5 (GLI3): c.3635delG (p.(Gly1212Alafs*18)) but did not detect any other possibly deleterious mutation that could explain the unusual features of camptodactyly, hypoplasia of third toe and wide space between first and second toes. Our findings further expand the phenotypic variability of GLI3 polydactyly. We also present a review of GLI3-associated isolated limb anomalies, which indicates that GLI3 mutation leads primarily to two well-established polydactyly types: postaxial types A and B and crossed polydactyly type I. In addition, a variety of other minor digit anomalies generally accompany polydactyly, and there is no straightforward genotype-polydactyly phenotype correlation.     

The Greig cephalopolysyndactyly syndrome: report of a family and review of the literature

The Greig cephalopolysyndactyly syndrome in characterized by a set of craniofacial defects (macrocephaly, broad nasal root) leading to peculiar facial appearance, postaxial (occasionally preaxial) polydactyly of hands, preaxial (rarely postaxial) polydactyly of feet, and syndactyly of fingers and toes. Occasionally other skeletal or nonskeletal defects are present. This is an autosomal dominant trait with complete penetrance and variable expressivity. Prognosis for mental and physical development of the affected patients is good, surgery being indicated primarily for aesthetic and functional correction of polydactyly and syndactyly. We report on a Brazilian family in whom the mother and two of three sons were affected.