J Med Genet 1992; 29: 635-637 635 The acrocallosal syndrome and Greig syndrome J Med Genet: first published as 10.1136/jmg.29.9.635 on 1 September 1992. Downloaded from are not allelic disorders Louise A Brueton, Kokila A Chotai, Lynne van Herwerden, Albert Schinzel, Robin M Winter Abstract (male and female first cousins whose mothers Acrocallosal syndrome is an autosomal were sisters). recessive form of polysyndactyly associ- ated with mental retardation and agene- sis of the corpus callosum. There have DNA ANALYSIS been suggestions that it is allelic to the Several chromosome 7p probes, R-944, P137, Greig cephalopolysyndactyly syndrome. EGFR, and TCRG, all known to be in the Linkage analysis, using flanking markers, close vicinity of the GCPS locus, were used to shows this suggestion is unlikely to be detect restriction fragment length polymor- correct. phisms, together with Ef', an 842 base pair (J7 Med Genet 1992;29:635-7) fragment from the 3' end of the GLI3 gene, which has been found to detect a rare TaqI polymorphism (M Farrall, personal communi- The acrocallosal syndrome, first described by cation). The probe R-944 contains highly Schinzel,l is characterised by the combination repetitive human sequences and so to facilitate of pre- and postaxial polydactyly, syndactyly, studies using this probe, a 2-4 kb EcoRI frag- severe mental retardation, agenesis or hypo- ment was subcloned into the plasmid pUC 13. plasia of the corpus callosum, hypertelorism, a Standard protocols were used for isolation of prominent forehead, and macrocephaly. 1-3 genomic DNA from lymphocytes, restriction Fewer than 20 cases have been reported'-'7 and enzyme digestion of DNA, agarose gel electro- several of the cases described have originated phoresis, and Southern transfer to nylon mem- from a small area of Switzerland.21314 Reports branes (Hybond-N, Amersham plc).27 The of parental consanguinity,"'1617 affected sibs,"4 probes were 32p labelled by random oligonuc- and affected first cousins'3 provide evidence for leotide primed synthesis of the probe insert.28 autosomal recessive inheritance. After hybridisation, filters were washed at a The digital changes and dysmorphic final stringency of 05 x SSC/0-1% SDS at features observed in the acrocallosal syndrome 65°C and exposed to x ray film for two to seven are similar to those of Greig cephalopolysyn- days. http://jmg.bmj.com/ dactyly (GCPS) and in view of the consider- able phenotypic overlap between the two dis- orders several authors have considered the LINKAGE possibility that the Greig and acrocallosal syn- Linkage analysis between the acrocallosal syn- dromes could affect the same developmental drome and marker loci on the short arm of gene36 0 8 and represent either allelic muta- chromosome 7 was performed using the pro- tions or different sized contiguous deletions of gramme LIPED.29 A lod score of at least 3 was on September 26, 2021 by guest. Protected copyright. the same area. The finding of an extra bone considered evidence of genetic linkage and the within the anterior fontanelle in a patient with lod score of - 2-0 taken as an exclusion bound- the acrocallosal syndrome5 suggested similar- ary. ity to the Xt mouse mutant which is con- sidered homologous to GCPS in man,'9 further supporting the hypothesis that the Greig and Results acrocallosal syndromes may be allelic dis- SOUTHERN BLOT ANALYSIS Kennedy Galton orders. The knowledge that GCPS maps to DNA samples from four subjects with the Centre, Clinical 7p2023 allows testing of this hypothesis. Three acrocallosal were Research Centre, syndrome digested with Northwick Park balanced translocations involving 7pl3 and several different restriction enzymes and Hospital, Watford associated with GCPS in different families hybridised to DNA probes known to flank or Road, Harrow, have been reported212224 and two of the three be close to the GCPS locus on chromosome Middlesex HAl 3UJ. L A Brueton have recently been shown to interrupt the 7p. Using conventional methods of electro- K A Chotai GLI3 gene,25 a zinc finger gene previously phoresis no microdeletions or rearrangements L van Herwerden localised to 7p13.26 We have undertaken a were detected in these cases with R944, R M Winter P137, study to look for linkage to and microdeletions EGFR, GLI3, and TCRG probes. The poly- Department of of the region of the GCPS locus on chromosome morphic characteristics and regional assign- Medical Genetics, 7p in patients with the acrocallosal syndrome. ments of these probes are given in the table. University of Zurich, Switzerland. A Schinzel Materials and methods LINKAGE STUDY Correspondence to Dr Winter. Four patients with the acrocallosal syndrome Linkage analysis of the data obtained on the Received 2 March 1992. and their families participated in the study. family with the affected first cousins generated Accepted 30 March 1992. Two cases were sporadic and two familial a lod score of -2-7 (0=0 01) with probe P137 636 Brueton, Chotai, van Herwerden, Schinzel, Winter Details of probes used in this study. DNA probe HGM symbol Cytogenetic location Enzyme RFLP size (kb) J Med Genet: first published as 10.1136/jmg.29.9.635 on 1 September 1992. Downloaded from pHER-A64 EGFR 7pl2-pl3 StuI;XbaI 20/13-7; 12/10 CRI-R944 D7S69 7pl3 MspI 4 0/3 0 CRI-P137 D7S65 7pl3 TaqI 3-7/2-7,1-0 Ef' GLI3 7p13 TaqI +/-3 pTgamma-1 TCRG 7pl4-p15 XbaI 28/23/5-4/3-6 pV11SPRS TCRG 7p14-p15 TaqI 4-1/3 7 and -3 1 (0=0 01) with EGFR. EGFR is TCRG gene shown by dosage analysis in the proximal to the GCPS translocation break- other." Recent studies suggest that GLI3, a point and P137 flanks it distally. The affected zinc finger gene mapping to 7p13, is likely to children have inherited different P137 and be the gene responsible for GCPS.30 However, EGFR alleles from their mothers who are no deletions or rearrangements were detected sisters (figure). The results indicate a double with EGFR, GLI3, or TCRG probes in the crossover in this family with these two flanking acrocallosal cases under investigation. The re- probes and provide evidence that the acrocal- sults of linkage analysis suggest that the acro- losal syndrome does not map in the same callosal syndrome does not map to the same region as GCPS. The R944, GLI3, and TCRG region as GCPS. Even on the most conserva- probes were largely uninformative. tive estimates the chance of a double crossover between P137 and EGFR is less than 1 in 100. This provides evidence that the acrocallosal Discussion and Greig syndromes are neither allelic muta- The data presented here give no support to the tions nor represent different sized contiguous suggestion that GCPS and the acrocallosal deletions of the same area. syndromes are allelic disorders. The probes CRI-R944 and P137 have been shown to flank We would like to thank Dr Han Brunner for the Greig 3;7 translocation breakpoint30 and referring a family to the study. The EGF R944 is deleted in a patient with GCPS and an receptor probes pC7 and pHER-64-1 and T interstitial deletion of chromosome 7pl3-14.31 cell receptor probe pVII SPRS were obtained No microdeletions or rearrangements of DNA from ATCC. The two anonymous probes sequences were recognised by these probes in CRI-R944 and CRI-P137 were from Colla- four patients with the acrocallosal syndrome. borative Research Incorporated. The T cell y P137 is proximal to TCRG.30 Although there probe PTy 1 was kindly provided by Dr R are no detailed linkage data between GCPS Holcombe. Dr M Farrall supplied the Ef' and P137, TCRG maps about 5 cm from probe. We are grateful to Mrs Sheila Kingsley GCPS (Brueton et al, unpublished observa- and Ms L Sargeant for secretarial assistance. tion). Close linkage of EGFR, localised to 1 Schinzel A. Postaxial polydactyly, hallux duplication, ab- http://jmg.bmj.com/ 7p12-13, to GCPS has been shown."0 In addi- sence of the corpus callosum, macroencephaly and severe tion Rosenkranz et all studied two patients mental retardation: a new syndrome? Helv Paediatr Acta 1979;34: 141-6. with GCPS resulting from cytogenetically 2 Schinzel A, Schmid W. Hallux duplication, postaxial poly- visible deletions of the short arm of chromo- dactyly, absence of the corpus callosum, severe mental retardation and additional anomalies in two unrelated some 7. There was a deletion of the EGFR patients: a new syndrome. Am J Med Genet 1980;32:301- gene in one of them and hemizygosity for the 5. 3 Schinzel A. Four patients including two sisters with the acrocallosal syndrome (agenesis of the corpus callosum in combination with preaxial hexadactyly). Hum Genet on September 26, 2021 by guest. Protected copyright. 1982;62:382. 1 2 4 Casamassima AC, Beneck D, Gewitz MH, et al. Acrocallo- sal syndrome: additional manifestations. Am J Med Genet 1989;32:31 1-7. 5 Hendricks HJE, Brunner HG, Haagen TAM, et al. Acro- callosal syndrome. Am J Med Genet 1990;35:443-6. 6 Legius E, Fryns JP, Casaer P, et al. Schinzel acrocallosal syndrome: a variant example of the Greig syndrome? Ann Genet (Paris) 1985;28:239-40. 7 Moeschler JB, Pober BR, Holmes LB, et al. Acrocallosal syndrome: new findings. Am J Med Genet 1989;32:306- 10. 8 Nelson MM, Thomson AJ. The acrocallosal syndrome. Am 11 J Med Genet 1982;12:195-9. 9 Rosenkranz W, Kroisel PM, Wagner K. Deletion of the EGFR gene in one of two patients with Greig cephalopo- lysyndactyly syndrome and microdeletion of chromosome 7. Cytogenet Cell Genet 1989;51:1069. 10 Philip N, Apicella N, Lassman I, et al.