Greig Cephalopolysyndactyly Syndrome

A number sign (#) is used with this entry because of evidence that Greig cephalopolysyndactyly syndrome (GCPS) is caused by heterozygous mutation in the GLI3 gene (165240) on chromosome 7p14.

Mutations in the GLI3 gene can also cause Pallister-Hall syndrome (PHS; 146510) and 2 forms of isolated polydactyly: postaxial polydactyly type A1 (174200) and preaxial polydactyly type IV (174700).

The acrocallosal syndrome (200990) shows some phenotypic overlap with GCPS.

Description

Greig cephalopolysyndactyly syndrome is characterized by frontal bossing, scaphocephaly, and hypertelorism associated with pre- and postaxial polydactyly and variable syndactyly. The phenotype shows variable expressivity and can also include craniosynostosis. Affected individuals usually have normal psychomotor development (summary by Gorlin et al., 2001).

Clinical Features

Greig (1928) described digital malformations and peculiar skull shape in mother and daughter. The mother had syndactyly of both hands. The daughter, of above average intelligence, had polysyndactyly and a peculiar skull shape in the form of expanded cranial vault leading to high forehead and bregma, with no evidence of precocious closure of cranial sutures. The thumbs and great toes had bifid terminal phalanges.

Marshall and Smith (1970) reported a family with dominant inheritance of what they termed 'frontodigital syndrome.' Intelligence was normal.

Merlob et al. (1981) reported a female infant with postaxial polydactyly of the hands, preaxial polydactyly of the feet, with syndactyly, and craniofacial dysmorphism characterized by frontal bossing. X-ray examination revealed markedly advanced bone age. There was also bilateral hip dislocation. The father of the infant had a high forehead and mild hypertelorism. Fryns et al. (1981) described the disorder in dizygotic 4-month-old twin brothers and their father; the twins had severe affection, the father mild.

Chudley and Houston (1982) described the syndrome in 3 generations of a family and perhaps by implication in a fourth. They commented on phenotypic overlap with the acrocallosal syndrome (ACLS; 200990). Baraitser et al. (1983) reported 13 affected persons in 3 kindreds with, curiously, no male-to-male transmission. They also commented on similarity to the acrocallosal syndrome. The main clinical distinction was mental retardation, involving agenesis of the corpus callosum. Legius et al. (1985) proposed that the acrocallosal syndrome is the same as Greig syndrome.

Marafie et al. (1996) reported Bedouin father and son with Greig cephalopolysyndactyly syndrome; the son had the rare association of mild mental retardation and dysgenesis of the corpus callosum. They noted that dysgenesis of the corpus callosum with mild mental retardation had been reported in only 1 other patient with GCPS (Hootnick and Holmes, 1972).

Baraitser et al. (1983) observed that the facial features of Greig syndrome can be so mild as to be indistinguishable from the normal. Therefore they suggested that type IV preaxial polydactyly, or uncomplicated polysyndactyly (174700), as delineated by Temtamy and McKusick (1978), may be Greig syndrome.

The family reported by Ridler et al. (1977) as an example of type II syndactyly (186000) was in fact a family with Greig syndrome, as established by Winter (1989), who revisited the family.

Clinical Variability

Gorlin et al. (2001) noted that there is markedly variable expressivity of Greig cephalopolysyndactyly syndrome, and that craniosynostosis has been rarely reported.

Hootnick and Holmes (1972) reported a father with polysyndactyly and his son with trigonocephaly, polysyndactyly, and agenesis of the corpus callosum (McDonald-McGinn et al., 2010). Gorlin et al. (2001) considered the father and son reported by Hootnick and Holmes (1972) had GCPS.

Guzzetta et al. (1996) reported a boy with trigonocephaly and digital anomalies, including syndactyly of the third and fourth fingers of both hands with bony fusion, bifid thumbs, preaxial polydactyly of the toes, and syndactyly of the first, second, and third rays of the feet. He also had partial agenesis of the corpus callosum but normal development at age 11 months. Guzzetta et al. (1996) discussed the differential diagnosis as including GCPS and Carpenter syndrome (see 201000), and Fryns et al. (1997) later noted the phenotypic overlap with acrocallosal syndrome (ACLS; 200990).

McDonald-McGinn et al. (2010) reported 2 unrelated patients with craniosynostosis of the metopic suture resulting in trigonocephaly and multiple digital anomalies associated with 2 different heterozygous mutations in the GLI3 gene (165240.0020 and 165240.0021, respectively). One patient had full digit postaxial polydactyly of all 4 limbs, whereas the other had bilateral complete cutaneous syndactyly of the third and fourth fingers, duplication of the great toe on the right with soft tissue syndactyly of toes 2 and 3, and medial deviation of the great toe on the left. Neither patient had structural brain anomalies, and both had normal development at ages 14 months and 13 years, respectively. The presence of trigonocephaly expanded the phenotype associated with GLI3 mutations. Kini et al. (2010) also reported a child with Greig syndrome and metopic synostosis resulting from a GLI3 mutation. The child also had speech delay.

Biesecker (2008) reviewed GCPS, noting the phenotypic overlap with acrocallosal syndrome (ACLS; 200990). He remarked that in patients with substantial phenotypic overlap, molecular diagnostics are essential to arrive at a correct diagnosis; a mutation in GLI3 denotes GCPS. He classified the patient of Elson et al. (2002), with a phenotype 'indistinguishable from acrocallosal syndrome,' as a case of GCPS (see 165240.0013).

Demurger et al. (2015) reported the molecular and clinical results from their study of a cohort of 76 probands with either a GLI3 mutation (49 with GCPS and 21 with PHS) or a large deletion encompassing the GLI3 gene (6 with GCPS). Only 10 patients with GCPS fulfilled all clinical criteria, namely preaxial polydactyly, cutaneous syndactyly, widely spaced eyes, and macrocephaly. Anomalies of the corpus callosum were found in 9 patients, 7 of whom had a truncating mutation in the C-terminal domain of the protein. Macrosomia was observed in at least 13% of individuals diagnosed with GCPS. Craniosynostosis was found in only 2 patients, confirming its rare association with GCPS.

Inheritance

Temtamy and McKusick (1978) studied a particularly instructive family in which 10 members of 4 generations in 6 sibships were affected in the pattern of a fully penetrant autosomal dominant trait.

Fryns (1982) documented the variability and autosomal dominant inheritance on the basis of 7 cases. In 1 family, a mother and son were affected.

Gollop and Fontes (1985) described affected mother and 2 of her 3 sons.

Cytogenetics

In an analysis of reported cases, Baccichetti et al. (1982) suggested that deletion of part of the 7p21 may be critical in GCPS. Tommerup and Nielsen (1983) described a translocation t(3;7)(p21.1;p13) segregating through 4 generations in invariable association with GCPS. High resolution cytogenetic analysis using G- and R-banding did not uncover any imbalance of the affected chromosomes, nor were the late replicating patterns changed. A girl with GCPS died with medulloblastoma. Sage et al. (1987) subjected the breakpoints on chromosome 3 and chromosome 7 to molecular genetic analysis. Drabkin et al. (1989) identified 2 very closely linked DNA sequences that flanked the 3;7 translocation breakpoint; no recombination between the disorder and these sequences was found. A pulsed field analysis showed that the disorder was also linked to the TCRG locus (see 186970), but Drabkin et al. (1989) found no evidence of linkage to EGFR (131550).

Motegi et al. (1985) reported an affected boy who had a tiny deletion of 7p21.3-p15.3. From comparison with other cases of 7p deletion, with or without craniosynostosis, they suggested that the critical segment for craniosynostosis may be at 7p21.2 or the proximal part of 7p21.3.

In 7 GCPS pedigrees with no chromosome abnormality, Brueton et al. (1988) found linkage to EGFR, which is located at 7p13-p11 (maximum lod score of 3.17 at theta = 0.0). In a patient with Greig cephalopolysyndactyly syndrome and deletion of 7p13-p11.2, Rosenkranz et al. (1989) found molecular evidence of deletion of the EGFR gene. However, the EGFR genes were intact in a second patient with deletion of 7p14.2-p12.3. From the data available, the authors concluded that the EGFR gene is probably in band 7p12.3-p12.1 and the GCPS gene more distally situated in 7p13-p12.3.

Pettigrew et al. (1989, 1991) confirmed the assignment to 7p13 by study of the sporadic case of an 11-month-old infant with typical features including macrocephaly, frontal bossing, syndactyly, postaxial polydactyly of the hands, and preaxial polydactyly of the feet. High resolution chromosome analysis showed a 46,XX,del(7)(p13p14)pat chromosome pattern. This was the first report of an interstitial deletion associated with Greig syndrome. Cytogenetic analysis of polymorphisms of the heterochromatin in the pericentromeric region suggested that the deleted chromosome was of paternal origin. Review of clinical features and published reports of patients with a deletion involving 7p13 showed a number to have features overlapping with Greig syndrome.

Kruger et al. (1989) reported on cases of Greig syndrome segregating in a large kindred over 4 generations. The disorder was due to reciprocal translocation t(6;7)(q27;p13). One patient in this pedigree had a severe malformation syndrome due to duplication 7pter-p13. Wagner et al. (1990) studied 2 patients with GCPS and a cytogenetically visible microdeletion of 7p with gene probes that had been assigned close to the proposed Greig locus. One patient showed loss of the TCRG gene cluster and both showed hemizygosity for PGAM2 (612931). On the other hand, HOX-1.4 (HOXA4; 142953) and IFNB2 (147620) showed normal gene dosage. This suggested that PGAM2 and GCPS are in 7p13-p12.3; TCRG in the distal part of 7p14.2-p13; and HOX-1.4 and IFNB2 distal to 7p14.2. The findings excluded the HOX-1.4 gene from involvement in the pathogenesis of GCPS.

Kroisel et al. (2001) described 5 patients with Greig syndrome, including 3 unrelated patients and a pair of monozygotic twin boys with a de novo microdeletion involving 7p13. Because of the considerable lack of well-defined clinical delineation of reported patients with GCPS and microdeletions involving 7p13, the authors focused on the symptoms not typically related to GCPS, such as moderate psychomotor retardation, seizures, muscle fiber anomalies, cardiac anomalies, hyperglycemia, and hirsutism. Their observations suggested that the presence of a cytogenetically detectable microdeletion or a submicroscopic deletion of 7p13 should be suspected in all cases of atypical GCPS.

Molecular Genetics

Vortkamp et al. (1991) used a candidate gene approach to test the possible implication of the GLI3 gene in this disorder, since the GLI3 gene had been mapped to 7p13. Vortkamp et al. (1991) demonstrated that 2 of 3 translocations found to be associated with GCPS interrupt the GLI3 gene. The breakpoints were within the first third of the coding sequence. In the third translocation, chromosome 7 was broken at about 10 kb downstream of the 3-prime end of GLI3.

In patients with GCPS, Wild et al. (1997) identified heterozygous point mutations in the GLI3 gene (165240.0018 and 165240.0019).

Sobetzko et al. (2000) described a newborn infant with an unusual combination of syndactylies, macrocephaly, and severe skeletal dysplasia. A history of digital anomalies in the father and grandfather led to the diagnosis of Greig cephalopolysyndactyly syndrome. The skeletal changes were thought to fit best congenital spondyloepiphyseal dysplasia (SEDC; 183900), a type II collagen disorder. Molecular analysis confirmed the presence of 2 dominant mutations in the infant: a GLI3 mutation (E543X; 165240.0010), which was present also in the father and grandfather, and a de novo COL2A1 mutation leading to a gly973 to arg (G973R; 120140.0031) substitution. Thus, this boy combined the syndactyly-macrocephaly phenotype of Greig syndrome with a severe form of SED caused by de novo mutation in type II collagen. The diagnostic difficulties posed by the combination of 2 genetic disorders and the usefulness of molecular diagnostics were well illustrated.

Debeer et al. (2003) presented clinical and radiologic findings of 12 patients with GCPS derived from 4 independent families and 3 sporadic cases with documented GLI3 mutations, with particular emphasis on inter- and intrafamilial variability. In a particularly instructive family in which 9 members of 4 generations could be studied clinically and molecularly, a missense mutation, R625W (165240.0012), was transmitted and showed a partially penetrant pattern. In a branch of the family, the GCPS phenotype skipped a generation via a normal female carrier without clinical signs, providing evidence that GCPS does not always manifest full penetrance.

Hurst et al. (2011) studied 5 sporadic patients with trigonocephaly due to metopic synostosis in association with pre- and postaxial polydactyly and cutaneous syndactyly of the hands and feet. In all 5 children, diagnosis of GCPS was confirmed by molecular analysis of GLI3, which revealed heterozygosity for a missense mutation and a nonsense mutation in 2 patients, respectively, as well as 3 complete gene deletions detected by array CGH in the remaining 3 patients. Three of the patients had been referred with a clinical diagnosis of Carpenter syndrome (see 201000), which shows overlapping features with GCPS, including craniosynostosis and polysyndactyly; however, additional features that would point to Carpenter syndrome, such as fusion of the coronal or lambdoid sutures, high birth weight, umbilical hernia, and hypogenitalism in males, were absent in these patients. Hurst et al. (2011) also noted that 1 of these patients had hypoplasia of the corpus callosum, a feature that could cause confusion with acrocallosal syndrome.

Genotype/Phenotype Correlations

Using FISH and STRP analyses in the study of 34 patients with characteristics of GCPS, Johnston et al. (2003) found that 11 had deletions. Mental retardation or developmental delay was present in 9 patients with deletions in whom the disorder was classified as severe GCPS. These patients had manifestations that overlapped with the acrocallosal syndrome. The deletion breakpoints were analyzed in 6 patients whose deletions ranged in size from 151 kb to 10.6 Mb. Junction fragments were found to be distinct with no common sequences flanking the breakpoints. Johnston et al. (2003) concluded that patients with GCPS caused by large deletions that include GLI3 are likely to have cognitive deficits, and hypothesized that the severe GCPS phenotype is caused by deletion of contiguous genes.

Johnston et al. (2005) hypothesized that GLI3 mutations that predict a truncated functional repressor protein cause Pallister-Hall syndrome (PHS; 146510), whereas haploinsufficiency of GLI3 causes GCPS. To test this hypothesis, they screened 46 patients with PHS and 89 patients with GCPS for GLI3 mutations. They detected 47 pathologic mutations (among 60 probands), and when these mutations were combined with previously published mutations, 2 genotype-phenotype correlations were evident. GCPS was caused by many types of alterations, including translocations, large deletions, exonic deletions and duplications, small in-frame deletions, and missense, frameshift/nonsense, and splicing mutations. In contrast, PHS was caused only by frameshift/nonsense and splicing mutations. Among the frameshift/nonsense mutations, Johnston et al. (2005) found a clear genotype/phenotype correlation. Mutations in the first third of the gene (from open reading frame nucleotides 1-1997) caused GCPS, and mutations in the second third of the gene (from nucleotides 1998-3481) caused primarily PHS. Surprisingly, there were 12 mutations in patients with GCPS in the 3-prime third of the gene (after open reading frame nucleotide 3481), and no patients with PHS had mutations in this region. These results demonstrated a robust genotype/phenotype correlation for GLI3 mutations and strongly supported the hypothesis that these 2 allelic disorders have distinct modes of pathogenesis.

Furniss et al. (2007) identified a heterozygous nonsense mutation in the GLI3 gene (R792X; 165240.0016) in a patient with GCPS. The mutation was demonstrated to result in nonsense-mediated mRNA decay. Furniss et al. (2007) postulated that the relatively mild phenotype in this patient, which was less severe than that observed in Pallister-Hall syndrome, may be due to nonsense-mediated mRNA decay that eliminates a toxic dominant-negative effect of a mutant protein.

Demurger et al. (2015) reported the molecular and clinical results from a study of 76 probands from 55 families who had either a mutation in GLI3 (49 with GCPS and 21 with PHS) or a large deletion encompassing GLI3 (6 with GCPS). Most of the mutations they identified were novel and supported previously reported genotype/phenotype correlations. Truncating mutations in the middle third of the gene generally resulted in PHS, whereas exonic deletions and missense and truncating mutations elsewhere in the gene caused GCPS.

History

D. M. Greig, a Scot, pronounced his name 'Gregg' (Ferguson-Smith, 1996).

Animal Model

Winter and Huson (1988) called attention to the evidence that, on both morphologic and comparative gene mapping grounds, Greig cephalopolysyndactyly syndrome is homologous to the mouse mutant 'extra toes' (Xt) on mouse chromosome 13. The pattern of polydactyly in the 2 species is very similar and both conditions probably map close to the T-gamma receptor locus (TCRG; see 186970). Vortkamp et al. (1992) reported deletion in the 5-prime end of the Gli3 gene in an Xt mutant, and Schimmang et al. (1992) reported that expression of Gli3 is reduced in this mutant. Hui and Joyner (1993) described the molecular characteristics of the Xt mutation. They found that deficiency of expression of Gli3 in the mutant mouse is due to a deletion within the 3-prime end of the gene. Furthermore, structures affected in the mouse mutant and in the human syndrome were found to correlate with expression domains of Gli3 in the mouse. These findings strongly supported the suggestion that deficiency of GLI3 function leads to human GCPS.