470 Med Genet 1995;32:470-474 Diagnostic issues in a family with late onset type 2 neurofibromatosis D G R Evans, D Bourn, A Wallace, R T Ramsden, J D Mitchell, T Strachan Abstract of a family of genes which encode proteins We report a family with type 2 neuro- thought to interact with membrane and cyto- fibromatosis and late onset tumours. Five skeletal proteins including genes encoding mer- members of this family have developed lin, ezrin, radixin, erythrocyte band 4.1 protein, hearing loss late in life, two ofwhom have and others.56 Characterisation of the gene cod- only been shown to have the diagnosis in ing sequence56 and identification ofintron/exon their seventies, and three other obligate boundaries7 has permitted mutation screening. gene carriers died undiagnosed at 64, 72, We report a family which is unusual for the and 78 years of age. A missense mutation late onset of symptoms in which we have iden- at the C-terminal end of the NF2 protein tified the causative mutation and in whom has been identified in this family and se- predictive testing is easily achieved with linked gregates with disease. The use of highly markers. polymorphic markers for predictive test- ing is also shown. There appears to be an autosomal dominant form of spino- cerebellar degeneration which is se- Case report gregating separately to NF2 in this family, The family pedigree is shown in fig 1 and which created a diagnostic dilemma. clinical details in the table. The proband (401), a woman, presented at (JrMed Genet 1995;32: 470-474) the age of 30 years with progressive hearing loss starting initially on the right side. She then developed severe headaches secondary to Type 2 neurofibromatosis (NF2) is an auto- hydrocephalus and underwent a CT scan aged somal dominant disorder predisposing to tu- 33 years which showed bilateral large VS mours ofneurogenic origin. The great majority (3 cm). In the following 16 months she under- of people with NF2 will present in the second went excision of both tumours through a trans- and third decades with bilateral vestibular labyrinthine approach as well as shunting Department of schwannomas (VS) and many will also develop procedures. Following these operations she was Medical Genetics, schwannomas of other cranial nerves, spinal completely deaf, but has learnt to lip read well. St Mary's Hospital, Hathersage Road, nerve roots, and peripheral nerves.'2 In ad- Since then she has had three skin lumps excised Manchester M13 OJH, dition about 50% will also develop cranial or from her arms all of which were reported as UK spinal meningiomas.' It has been suggested "neurofibromas". However, the pathology has D G R Evans A Wallace that there is concordance of disease severity in not been reviewed. In addition to this she has families, but not between them, and that this two further intracutaneous plaques, but no cafe CRC Department of may reflect a genotype/phenotype correlation.34 au lait patches. She has recently undergone Cancer Genetics, remove a cervical Paterson Institute for Recently, the NF2 gene has been mapped to surgery to large spinal Cancer Research, chromosome 22q 1 2 and identified as a member schwannoma. Christie Hospital, Manchester, UK D G R Evans Features of NF2 and spinocerebellar degeneration in family members Division of Human Subject Age (y) Dfns onset BVS Spnl tum Cranl mening CAL Skin tum Tremor Ataxia NF2 mut Genetics, University of Newcastle upon Tyne, 101 +72 52 dk dk dk dk dk dk dk dk UK 201 +64 44 dk dk dk dk dk dk dk dk 202 + 78 50 dk dk dk dk dk dk dk dk D Bourn 203 +86 no dk dk dk dk dk dk dk dk T Strachan 301 70 61 yes no no no no yes yes yes 302 68 no - - - no no yes yes no Department of 303 72 no - - - no no no no no Neurology, Royal 304 63 no - - - dk dk dk dk dk Preston Hospital, 305 72 52 yes no yes no no no no yes Preston PR2 4HT, UK 306 59 43 yes yes yes no no no no yes 307 66 no - dk dk dk dk dk dk dk J D Mitchell 401 37 30 yes yes no no 5 no no yes 402 41 no no no no no no yes yes no Department of 403 21 no - - - dk dk dk dk dk Otolaryngology, 404 28 no - - - no no no no no Manchester Royal 405 37 no - - - dk dk no no no Infirmary, 406 33 no - - - dk dk dk dk dk 501 15 no - - - no no no no yes Manchester, UK - - - no no yes R T Ramsden 502 12 no no no CAL=cafe au lait; tum=tumour; spnl=spinal; cranl mening=cranial meningioma; BVS=bilateral vestibular schwannomas on Correspondence to: scan; Dfns=deafness; mut=mutation. Dr Evans. dk=where the presence of a feature was not known; -=no evidence clinically; no is entered for CNS tumours when CT or Received 17 August 1994 MRI must have been performed. Revised version accepted for No evidence for cataracts was found on slit lamp examination in 306, 401, 501, and 502 and on ophthalmoscopy in 301 and publication 1 February 1995 305. Diagnostic issues in a family with late onset type 2 neurofibromatosis 471 -0 101 102 72y 202 203 lI 201 78 y 86 y 64y ( 0 ii 307 306 305 302 303 304 301 66 y 65 y 72 y 68 y 72 y 63 y 70 y Colon cancer 4 4 4 4 4 2 D22S275 D22S280 3 W 4 W 1 4 1 4 0 0 4 4 ( 406 405 404 403 402 401 33 y 37 y 28 y 29 y 42 y 37 y 4 4 3 4 4 4 4 5 3 3 4 L; 4 5 2 L 501 502 15y 12y 4 2 4 2 Figure 1 Pedigree symbols shaded in the left half represent people with evidence of spinocerebellar degeneration; those shaded in the right half represent people with bilateral deafness and presumed or proven NF2. Quoted age in years is age at death or current age. Boxed haplotypes represent inferred NF2 associated haplotype. The father of 401 (301) presented aged 22 MRI scan was arranged when he was 70 years years with a progressive ataxia and, more lat- of age as a cousin (306) had recently been terly, incessant tremor. He only began to notice diagnosed as having bilateral VS. This clearly hearing loss at the age of 61 years and still showed bilateral enhancing lesions in the acous- retains some serviceable hearing. On exam- tic meati. ination aged 64 years he had marked tremor A cousin of401 (305) presented with hearing especially in his hands as well as cerebellar loss aged 52 years which was attributed to his ataxia. Nerve conduction studies showed an work as an engineer. This became progressively axonal degenerative pattern, but brain stem worse until he developed seizures aged 71 years. evoked potentials and a CT scan were all re- After his sister (306) was diagnosed with NF2 ported as normal. In the light of the history of he underwent a CT scan which showed a 9 cm NF2 in his daughter the CT scan was repeated frontal meningioma, but no evidence of VS. one year later with contrast, but no abnormality However, MRI scanning showed intracana- was detected in the acoustic meati or canals. licular tumours. In view of the clear history of a similar pattern of ataxia and tremor in his father (201), sister (302), and daughter (402) it was felt that these Molecular analysis features represented an autosomal dominant Details of the methods for molecular analysis spinocerebellar degeneration syndrome. An are shown in the appendix.8 472 Evans, Bourn, Wallace, Ramsden, Mitchell, Strachan tremor had clearly not inherited the gene as was the case for 303, 405, and 403. However, both the children of 401 who continued to have normal brain stem evoked responses and subject 403 who is asymptomatic aged 29 years were shown to have inherited the family muta- tion. Figure 2 SSCP analysis. The PCR products analysed correspond to exon 15 of the NF2 gene spanning codons 525-579. Lane 1 subject 402, lane 2 subject 401, lane 3 Discussion subject 301, lane 4 subject 302, lane 5 subject 305, lane 6 The variability of disease course between famil- subject 305. Patient specific bands can be seen for affected and 401. ies and the relatively similar course within subjects 301, 305, 306, families has led previous authors to suggest a subdivision of NF2 into severe (Wishart) and Results mild (Gardner) subgroups.49 With the recent The haplotypes for the flanking microsatellite cloning of the NF2 gene"6 there has inevitably markers S275 and S280 are shown on the been a search for the elusive genotype/pheno- pedigree (fig 1). Linkage predictions for 302, type correlation to explain this. Early reports 303, 402, 404, and 405 showed a risk of <0 1 % of germline mutations have not provided any chance of being affected. Subjects 403, 501, concrete evidence for this,'°0 but we have pre- and 502 were at >99 9% chance ofbeing affec- viously reported a family which has a large ted. deletion encompassing the NF2 gene in which Genomic DNA samples prepared from peri- there is a mild phenotype.'2 The spectrum of pheral blood from two affected members of pathological mutations reported in NF2 the family (306 and 401) were amplified with patients include relatively few missense intron specific primers amplifying across all the mutations.671013 The residue affected in this exons of the NF2 gene.7 Amplified fragments instance, Leu 535, is conserved in the murine were screened for patient specific variants using NF2 homologue and in human moesin.' All SSCP analysis.