American J o u r n a l of Medical Genetics 4084-87 (1991)
Molecular Analysis of a Patient With Neurofibromatosis 1 and Achondroplasia ~~~~
Stefan-M. Pulst, Thomas Pribyl, David F. Barker, Vincent M. Riccardi, Meina Ren, Hana Yaari, and Julie R. Korenberg Division of Neurology (S. M. P., M . R., H. Y.),and Medical Genetics (T.P., J . R. K.), Cedars-Sinai Medical Center, University of California, Los Angeles; Department of Medical Informatics (D. F . B.), University of Utah School of Medicine, Salt Lake City The gene for von Recklinghausen neurofibromatosis (NF1)is on proximal 17q; the location of the gene for achondroplasia (ACH)is unknown. We have begun a molecular analysis of a patient with mental retardation, NF1 and ACH, a clinical presentation suggestive of a contiguous gene syndrome. In addition, this individual has a 47,XYY chromosome constitution. To define a possible chromosome 17 deletion, we investigated the copy number of DNA sequences linked to NF1 with conventional and pulsed-field gel electrophoresis (PFGE). We found no evidence for a deletion on chromosome 17. These results make it unlikely that this patient harbors a single deletion in the NF1 region causing both NF1 and ACH and suggest different mechanisms for the de novo occurrence of 2 autosomal dominant disorders in this individual.
patient with a deletion of Xp [F’rancke et al., 19851. This patient had come to medical attention because of the presence of DMD and other X-linked diseases in one individual. It was therefore of particular interest when a patient was identified with de novo NF1 and achondroplasia (ACH)[Wassman et al., 19881,another autosomal dominant disease with an unusually high mutation rate. Cytogenetic analysis of chromosome 17 did not show a deletion, but rather an XYY chromosome constitution. Two more patients with coincident NF1 and ACH have been identified in Washington, D.C. (Rosenbaum, personal communication) and in Vancouver, Canada [Edwards et al., 19881. Since the chance occurrence of de novo NF1 and ACH in one individual is less than 1in 600 million [reviewed in h l s t et al., 19901,their association suggested 2 alternative mechanisms for the de novo occurrence of these 2 autosomal dominant disorders. First, the genes for ACH and NF1 might be located physically close in the genome and a deletion spanning both genes, but too small to be cytogenetically visible, interrupts the function of both KEY WORDS: human chromosome 17,neurogenes. Such a deletion could greatly facilitate the clonfibromatosis 1, achondroplaing of the NF1 and the ACH genes. Second,if the 2 genes sia, molecular deletion analare not physically close, there may be an increased muysis, 47,XYY chromosome constitution. tation rate in either parent due to an as yet unidentified mechanism that causes multiple insertions, deletions, or single base changes. This patient may then provide the opportunity to define the mechanism(s1 causing INTRODUCTION multiple de novo mutations in one individual. We now Von Recklinghausen neurofibromatosis (NF1) is one present a molecular analysis of this patient to distinof the most common autosomal dominant disorders and guish between these alternatives. has one of the highest mutation rates of a single human locus [Collins et al., 19891. The NF1 gene has recently PATIENT AND METHODS been mapped to proximal 17q [Barker et al., 1987; Fain Patient et al., 1987; Seizinger et al., 1987; Goldgar et al., 19893. The cloning of the Duchenne muscular dystrophy Patient G. H. was described previously [Wassman et (DMD)gene was greatly facilitated by the analysis of a al., 19881. He has the typical physical and radiographic findings of ACH. Examination of the skin shows multiple cafe-au-lait spots and cutaneous neurofibromas. Received for publication June 13, 1990; revision received Sep- Both parents are normal and the family history is otherwise unremarkable. Paternal age was 29 years at the tember 20, 1990. Address reprint requests to Julie R. Korenberg, Ph.D., M.D., time of birth. Cytogenetic analysis showed a 47,XYY chromosome constitution and normal chromosomes 17 Medical-Genetics Birth-Defects Center, Cedars-Sinai Medical at the 700-band resolution level. Center, 8700 Beverly Blvd., Los Angeles, CA 90048.
0 1991 Wiley-Liss, Inc.
Neurofibromatosis and Achondroplasia
85
results for probes HHH202 and EW204 are shown in Figure 1and the results for all DNA probes are summarized in Table I. Patient G. H. is heterozygous for DNA probes tightly flanking the NF1 locus on the centromeric side (HHH202, VAW211, Beta8-2, and VAW215R2B) as well as for DNA probes flanking NF1 on the telomeric side (EW207, EW204, and CRI-L946). These DNA sequences are therefore present in the normal 2 copies. Further investigation of a possible small deletion utilized PFGE. The DNA from the patient, his parents, and several control individuals was digested with restriction enzymes that cut DNA infrequently. The resulting large DNA Probes DNA fragments (100-2,000 kb) were separated by The following DNA probes were used: HHH202 PFGE. Figure 2 shows DNA separated by PFGE and [White et al., 19871; Beta8-2 (genomic sequence of the probed with the DNA sequence pB4, a cDNA probe for beta-crystalline gene) [Barker et al., 19893; VAW211, the beta-crystalline gene. No change in fragment size VAW212, and VAW2lO [Fain et al., 19891; EW301, was detected. Similar results were obtained with DNA EW204, EW206, and EW207 [Fain et al., 19871; CRI- probe CRI-L946 (data not shown). L946 [Stephens et al., 19891; pB4 (cDNA for the betacrystalline gene); and ERBAl, ERBB2, HU-2, and MPO DISCUSSION (all obtained from ATCC). We performed a molecular analysis of a patient with. de novo ACH and NF1. We found no evidence for an RESULTS interstitial deletion in the NF1 region on chromosome The NF1 region on chromosome 17 has been well 17 using conventional and PFGE. Several possibilities characterized and multiple DNA probes are available may explain these findings. First, the NF and ACH genes may be physically close, for genetic and physical studies (Table I). Five DNA probes, HHH202, Beta8-2, and VAW211, VAW212, and but the deletion of chromosome 17 in individual G. H. is VAW215 have been localized to the region centromeric so small that none of the DNA probes investigated map to the NF1 gene [Fain et al., 19891. The remaining DNA within or close to the deletion. This possibility can be probes are located 5 cM telomeric to the NF1 region. excluded conclusively only when overlapping cosmid To determine the presence of a deletion in the NF1 clones for the NF1 region become available. However, region, we used quantitative Southern blot analysis [Ko- recent exclusion of the ACH gene from the NF1 locus by renberg et al., 19891 to determine the copy number of genetic linkage analysis supports the conclusion that DNA probes not known to be polymorphic (pB4, ERBB2, the NF1 and ACH genes are not physically close [Pulst. ERBA1, HU-2, and MPO). Except for pB4, these DNA et al., 19901. Second, the NF1 and ACH loci may be physically sequences are now known to map far telomeric to the NF1 locus [Goldgar et al., 19891. All probes tested were distant, but both located on chromosome 17. In this case, present in the normal 2 copies (data not shown). During a complex chromosome rearrangement may have interthe course of these studies highly polymorphic probes rupted the function of both genes without leading to tightly linked t o NF1 became available. This allowed us significant loss of DNA material. However, this explanato demonstrate the absence of a deletion without quan- tion seems unlikely in the absence of cytogenetic abnortitative Southern blotting by showing that the patient’s malities of chromosome 17 or fragment changes on DNA contained 2 alleles for a given DNA probe. The PFGE.
DNA digestion, electrophoresis, and hybridization procedures have been previously described [Pulst et al., 19901.For pulsed-field gel electrophoresis (PFGE) DNA was prepared from lymphoblastoid cell lines derived from individual G. H., his parents, and several unrelated controls as previously described [Schwartz and Cantor, 19841. DNA plugs were digested with Not1 and MZuI (Beckman) and separated by transverse, alternating gel electrophoresis (TAFE) according to the manufacturers specifications with switching times of 45 seconds for each direction.
TABLE I. Analysis for Heterozygosity With Chromosome 17 Markers Robe pEW301 pHHH202 pVAW2 11R3 ~ B e t a 8 - 2(BCRY) pVAW212 pVAW215R2B NF1 locus pEW207 pEW206 pVAW2 10M1 pEW204 CRI-L946
Restriction enzyme TaqI RsaI MspI MspI Psi1 RsaI BglII Hind111 MspI MspI BglII MspI BglII MspI
Homozygous
+ + + + +
+
Heterozygous
Distance to NF1 (cM)
+
3 1 1 1 0 0
+
5
+ + +
+ +
+
5 5 6 7
86
Pulst et al.
HHH202
EW204 -3.1kb
2.4kb
-
1.9
-
-2.2
Fig. 1. Autoradiogram of patient DNA digested with RsaI and probed with HHH202 and digested with MspI and probed with EW204. Size markers are taken from the 1 kb lambda ladder (BRL).
Thus, our analysis suggests that the NF1 and ACH genes are not physically close. Further study of the mutation in the NF1 gene in this patient may define the molecular basis of the multiple mutations in this individual and may provide insights into the aneuploidy of sex chromosomes.
ACKNOWLEDGMENTS This work was supported by grants from the Steven and Lottie Walker Foundation and grant NS 01428-01A1 from the National Institutes of Health. S. M. P. is the recipient of a Young Investigator Award from the National Neurofibromatosis Foundation and a Clinical Investigator Award from the National Institutes of Health. J. R. K is a National Down Syndrome Society Scholar. REFERENCES
1 2 3 4 5 6 7 0 9
- 1280kb
- 990
L
- 260 - 40
Fig. 2. Autoradiogram of MluI digested DNA from the patient and several normal controls separated by PFGE. Arrow points to hybridization signal detected by pB4. Lane 3: NF/ACH patient; lanes 2,4 parents of the patient; lanes 1,5,7-9 normal controls; lane 6 yeast chromosomal size markers (Beckman).
What, then, may explain the coincident occurrence of de novo NF1 and ACH? Since 3 cases of NF1 and ACH are known in the United States compared with 0.5 cases expected, random association cannot be excluded completely. However, the chance occurrence of de novo NF1, ACH, and a 47, XYY chromosome constitution in one individual is approximately 5 x given a frequency of 1 in 1,000 for the 47, XYY karyotype [Hook, 19751. Therefore, it is interesting to speculate that similar to mechanisms in Drosophila, activation of transposable elements may account for the increased mutation frequency [Busseau et al., 19891and aneuploidy (W. Engel, personal communication). Thus, insertional mutagenesis by retrotransposons could be an attractive mutational mechanism in this individual.
Barker DF, Fain PR, Wright EC, Nguyen K, Tsui LC (1989): MspI RFLP at CRYBl locus (17q11.2-17q12). Nucleic Acids Res 172327. Barker D, Wright E, Nguyen K, Cannon L, Fain P, Goldgar D, Bishop DT, Carey J , Baty B, Kivlin J, Willard H, Waye JS, Greig G, Leinwand L, Nakamura Y, O'Connell P, Leppert M, Lalouel J-M, White R, Skolnick M (1987): Gene for von Recklinghausen Neurofibromatosis is in the pericentromeric region of chromosome 17. Science 236:1100-1 100. Busseau I, Pelisson A, Crozatier M, Vaury C, Bucheton A (1989): Molecular lesions induced by hybrid dysgenesis in Drosophila melanogaster. Prog Nucleic Acid Res Mol Biol 36:lll-116. Collins FS, Ponder BA, Seizinger BR, Epstein CJ (1989): Editorial: The von Recklinghausen Neurofibromatosisregion on chromosome 17genetic and physical maps come into focus. Am J Hum Genet 44:l5. Edwards JH, Huson S, Ponder B (1988): Neurofibromatosis. Lancet 2:330. Fain PR, Barker DR, Goldgar DE, Wright E, Nguyen K, Johnson CJ, Kivlin J, Willard H, Mathew C, Ponder B, Skolnick M (1987): Genetic analysis of NF1: identification of close flanking markers on chromosome 17. Genomics 4:340-345. Fain PR, Goldgar DE, Wallace MR, Collins FS, Wright E, Nguyen K, Barker DF (1989): Refinedphysical and genetic mapping ofthe NF1 region on chromosome 17. Am J Hum Genet 45:721-728. Francke U, Ochs HD, De Martinville B, Giacalone J , Lindgren V, Disteche C, Pagon RA, Hofker MH, van Ommen G-JB, Pearson PL, Wedgwood RJ (1985): Minor Xp21 chromosome deletion in a male associated with expression of Duchenne muscular dystrophy, chronic granulomatous disease, retinitis pigmentosa, and McLeod syndrome. Am J Hum Genet 37:250-267. Goldgar DE, Green P, Parry DM, Mulvihill JJ (1989): Multipoint linkage analysis in neurofibromatosis type I: a n international collaboration. Am J Hum Gen 44:6-12. Hook ED (1975): The XYY genotype. Science 189:1044-1045. Korenberg JR, Pulst SM, Neve RL, West R (1989): The Alzheimer amyloid precursor protein maps to human chromosome 21 bands q21.105-q21.05. Genomics 5:124-127. Pulst SM, Graham JM, Fain P, Barker D, Pribyl T, Korenberg J R (1990): The achondroplasia gene is not linked to the locus for neurofibromatosis 1 on chromosome 17. Hum Genet 85:12-14. Schwartz DA, Cantor CR (1984):Separation of yeast-chromosome-sized DNA by pulsed field gradient gel electrophoresis. Cell 49:589-594. Seizinger BR, Rouleau GA, Ozelius LJ,Lane AH, Faryniarz AG, Chao MV, Huson S, Korf BR, Parry DM, Pericak-Vance MA, Collins FS, Hobbs WJ, Falcone BG, Lannazzi JA, Roy JC, St George-HyslopPH, Tanzi RE, Bothwell MA, Upadhyaya M, Harper P, Goldstein AE, Hoover DL, Bader JL, Spence MA, Mulvihill J J , Aylsworth AS, Vance JM, Rossenwasser G, Gaskell PC, Roses AD, Martuza RL, Breakefield XO, Gusella JF (1987): Genetic linkage of von Recklinghausen Neurofibromatosis to the nerve growth factor receptor gene. Cell 49:589-594.
Neurofibromatosis and Achondroplasia Stephens K, Green P, Riccardi V, Ng S, Rising M, Barker D, Darby JK, Falls KM, Collins FS, Willard HF, Donis-Keller H (1989):Genetic analysis of eight loci tightly linked to neurofibromatosis 1. Am J Hum Genet 44:13-19. Wassman ER, Kovacks B, Rimoin DL, Sparkes R, Alfi 0 (1988):Achon-
87
droplasia, neurofibromatosis, and 47,XYY as new mutational events in a single individual. Am J Med Genet (Suppl) 43:A99. White R,Nakamura y,OConnell, Leppert M, ~ ~JM, Barker l D,~ Goldgar D, Skolnick M, Carey J, Wallis CE, Slater CP, Mathew C, Ponder B (1987):Tightly linked markers for the neurofibromatosis type 1 gene. Genomics 1:364-367.
~
Molecular Analysis of a Patient With Neurofibromatosis 1 and Achondroplasia ~~~~
Stefan-M. Pulst, Thomas Pribyl, David F. Barker, Vincent M. Riccardi, Meina Ren, Hana Yaari, and Julie R. Korenberg Division of Neurology (S. M. P., M . R., H. Y.),and Medical Genetics (T.P., J . R. K.), Cedars-Sinai Medical Center, University of California, Los Angeles; Department of Medical Informatics (D. F . B.), University of Utah School of Medicine, Salt Lake City The gene for von Recklinghausen neurofibromatosis (NF1)is on proximal 17q; the location of the gene for achondroplasia (ACH)is unknown. We have begun a molecular analysis of a patient with mental retardation, NF1 and ACH, a clinical presentation suggestive of a contiguous gene syndrome. In addition, this individual has a 47,XYY chromosome constitution. To define a possible chromosome 17 deletion, we investigated the copy number of DNA sequences linked to NF1 with conventional and pulsed-field gel electrophoresis (PFGE). We found no evidence for a deletion on chromosome 17. These results make it unlikely that this patient harbors a single deletion in the NF1 region causing both NF1 and ACH and suggest different mechanisms for the de novo occurrence of 2 autosomal dominant disorders in this individual.
patient with a deletion of Xp [F’rancke et al., 19851. This patient had come to medical attention because of the presence of DMD and other X-linked diseases in one individual. It was therefore of particular interest when a patient was identified with de novo NF1 and achondroplasia (ACH)[Wassman et al., 19881,another autosomal dominant disease with an unusually high mutation rate. Cytogenetic analysis of chromosome 17 did not show a deletion, but rather an XYY chromosome constitution. Two more patients with coincident NF1 and ACH have been identified in Washington, D.C. (Rosenbaum, personal communication) and in Vancouver, Canada [Edwards et al., 19881. Since the chance occurrence of de novo NF1 and ACH in one individual is less than 1in 600 million [reviewed in h l s t et al., 19901,their association suggested 2 alternative mechanisms for the de novo occurrence of these 2 autosomal dominant disorders. First, the genes for ACH and NF1 might be located physically close in the genome and a deletion spanning both genes, but too small to be cytogenetically visible, interrupts the function of both KEY WORDS: human chromosome 17,neurogenes. Such a deletion could greatly facilitate the clonfibromatosis 1, achondroplaing of the NF1 and the ACH genes. Second,if the 2 genes sia, molecular deletion analare not physically close, there may be an increased muysis, 47,XYY chromosome constitution. tation rate in either parent due to an as yet unidentified mechanism that causes multiple insertions, deletions, or single base changes. This patient may then provide the opportunity to define the mechanism(s1 causing INTRODUCTION multiple de novo mutations in one individual. We now Von Recklinghausen neurofibromatosis (NF1) is one present a molecular analysis of this patient to distinof the most common autosomal dominant disorders and guish between these alternatives. has one of the highest mutation rates of a single human locus [Collins et al., 19891. The NF1 gene has recently PATIENT AND METHODS been mapped to proximal 17q [Barker et al., 1987; Fain Patient et al., 1987; Seizinger et al., 1987; Goldgar et al., 19893. The cloning of the Duchenne muscular dystrophy Patient G. H. was described previously [Wassman et (DMD)gene was greatly facilitated by the analysis of a al., 19881. He has the typical physical and radiographic findings of ACH. Examination of the skin shows multiple cafe-au-lait spots and cutaneous neurofibromas. Received for publication June 13, 1990; revision received Sep- Both parents are normal and the family history is otherwise unremarkable. Paternal age was 29 years at the tember 20, 1990. Address reprint requests to Julie R. Korenberg, Ph.D., M.D., time of birth. Cytogenetic analysis showed a 47,XYY chromosome constitution and normal chromosomes 17 Medical-Genetics Birth-Defects Center, Cedars-Sinai Medical at the 700-band resolution level. Center, 8700 Beverly Blvd., Los Angeles, CA 90048.
0 1991 Wiley-Liss, Inc.
Neurofibromatosis and Achondroplasia
85
results for probes HHH202 and EW204 are shown in Figure 1and the results for all DNA probes are summarized in Table I. Patient G. H. is heterozygous for DNA probes tightly flanking the NF1 locus on the centromeric side (HHH202, VAW211, Beta8-2, and VAW215R2B) as well as for DNA probes flanking NF1 on the telomeric side (EW207, EW204, and CRI-L946). These DNA sequences are therefore present in the normal 2 copies. Further investigation of a possible small deletion utilized PFGE. The DNA from the patient, his parents, and several control individuals was digested with restriction enzymes that cut DNA infrequently. The resulting large DNA Probes DNA fragments (100-2,000 kb) were separated by The following DNA probes were used: HHH202 PFGE. Figure 2 shows DNA separated by PFGE and [White et al., 19871; Beta8-2 (genomic sequence of the probed with the DNA sequence pB4, a cDNA probe for beta-crystalline gene) [Barker et al., 19893; VAW211, the beta-crystalline gene. No change in fragment size VAW212, and VAW2lO [Fain et al., 19891; EW301, was detected. Similar results were obtained with DNA EW204, EW206, and EW207 [Fain et al., 19871; CRI- probe CRI-L946 (data not shown). L946 [Stephens et al., 19891; pB4 (cDNA for the betacrystalline gene); and ERBAl, ERBB2, HU-2, and MPO DISCUSSION (all obtained from ATCC). We performed a molecular analysis of a patient with. de novo ACH and NF1. We found no evidence for an RESULTS interstitial deletion in the NF1 region on chromosome The NF1 region on chromosome 17 has been well 17 using conventional and PFGE. Several possibilities characterized and multiple DNA probes are available may explain these findings. First, the NF and ACH genes may be physically close, for genetic and physical studies (Table I). Five DNA probes, HHH202, Beta8-2, and VAW211, VAW212, and but the deletion of chromosome 17 in individual G. H. is VAW215 have been localized to the region centromeric so small that none of the DNA probes investigated map to the NF1 gene [Fain et al., 19891. The remaining DNA within or close to the deletion. This possibility can be probes are located 5 cM telomeric to the NF1 region. excluded conclusively only when overlapping cosmid To determine the presence of a deletion in the NF1 clones for the NF1 region become available. However, region, we used quantitative Southern blot analysis [Ko- recent exclusion of the ACH gene from the NF1 locus by renberg et al., 19891 to determine the copy number of genetic linkage analysis supports the conclusion that DNA probes not known to be polymorphic (pB4, ERBB2, the NF1 and ACH genes are not physically close [Pulst. ERBA1, HU-2, and MPO). Except for pB4, these DNA et al., 19901. Second, the NF1 and ACH loci may be physically sequences are now known to map far telomeric to the NF1 locus [Goldgar et al., 19891. All probes tested were distant, but both located on chromosome 17. In this case, present in the normal 2 copies (data not shown). During a complex chromosome rearrangement may have interthe course of these studies highly polymorphic probes rupted the function of both genes without leading to tightly linked t o NF1 became available. This allowed us significant loss of DNA material. However, this explanato demonstrate the absence of a deletion without quan- tion seems unlikely in the absence of cytogenetic abnortitative Southern blotting by showing that the patient’s malities of chromosome 17 or fragment changes on DNA contained 2 alleles for a given DNA probe. The PFGE.
DNA digestion, electrophoresis, and hybridization procedures have been previously described [Pulst et al., 19901.For pulsed-field gel electrophoresis (PFGE) DNA was prepared from lymphoblastoid cell lines derived from individual G. H., his parents, and several unrelated controls as previously described [Schwartz and Cantor, 19841. DNA plugs were digested with Not1 and MZuI (Beckman) and separated by transverse, alternating gel electrophoresis (TAFE) according to the manufacturers specifications with switching times of 45 seconds for each direction.
TABLE I. Analysis for Heterozygosity With Chromosome 17 Markers Robe pEW301 pHHH202 pVAW2 11R3 ~ B e t a 8 - 2(BCRY) pVAW212 pVAW215R2B NF1 locus pEW207 pEW206 pVAW2 10M1 pEW204 CRI-L946
Restriction enzyme TaqI RsaI MspI MspI Psi1 RsaI BglII Hind111 MspI MspI BglII MspI BglII MspI
Homozygous
+ + + + +
+
Heterozygous
Distance to NF1 (cM)
+
3 1 1 1 0 0
+
5
+ + +
+ +
+
5 5 6 7
86
Pulst et al.
HHH202
EW204 -3.1kb
2.4kb
-
1.9
-
-2.2
Fig. 1. Autoradiogram of patient DNA digested with RsaI and probed with HHH202 and digested with MspI and probed with EW204. Size markers are taken from the 1 kb lambda ladder (BRL).
Thus, our analysis suggests that the NF1 and ACH genes are not physically close. Further study of the mutation in the NF1 gene in this patient may define the molecular basis of the multiple mutations in this individual and may provide insights into the aneuploidy of sex chromosomes.
ACKNOWLEDGMENTS This work was supported by grants from the Steven and Lottie Walker Foundation and grant NS 01428-01A1 from the National Institutes of Health. S. M. P. is the recipient of a Young Investigator Award from the National Neurofibromatosis Foundation and a Clinical Investigator Award from the National Institutes of Health. J. R. K is a National Down Syndrome Society Scholar. REFERENCES
1 2 3 4 5 6 7 0 9
- 1280kb
- 990
L
- 260 - 40
Fig. 2. Autoradiogram of MluI digested DNA from the patient and several normal controls separated by PFGE. Arrow points to hybridization signal detected by pB4. Lane 3: NF/ACH patient; lanes 2,4 parents of the patient; lanes 1,5,7-9 normal controls; lane 6 yeast chromosomal size markers (Beckman).
What, then, may explain the coincident occurrence of de novo NF1 and ACH? Since 3 cases of NF1 and ACH are known in the United States compared with 0.5 cases expected, random association cannot be excluded completely. However, the chance occurrence of de novo NF1, ACH, and a 47, XYY chromosome constitution in one individual is approximately 5 x given a frequency of 1 in 1,000 for the 47, XYY karyotype [Hook, 19751. Therefore, it is interesting to speculate that similar to mechanisms in Drosophila, activation of transposable elements may account for the increased mutation frequency [Busseau et al., 19891and aneuploidy (W. Engel, personal communication). Thus, insertional mutagenesis by retrotransposons could be an attractive mutational mechanism in this individual.
Barker DF, Fain PR, Wright EC, Nguyen K, Tsui LC (1989): MspI RFLP at CRYBl locus (17q11.2-17q12). Nucleic Acids Res 172327. Barker D, Wright E, Nguyen K, Cannon L, Fain P, Goldgar D, Bishop DT, Carey J , Baty B, Kivlin J, Willard H, Waye JS, Greig G, Leinwand L, Nakamura Y, O'Connell P, Leppert M, Lalouel J-M, White R, Skolnick M (1987): Gene for von Recklinghausen Neurofibromatosis is in the pericentromeric region of chromosome 17. Science 236:1100-1 100. Busseau I, Pelisson A, Crozatier M, Vaury C, Bucheton A (1989): Molecular lesions induced by hybrid dysgenesis in Drosophila melanogaster. Prog Nucleic Acid Res Mol Biol 36:lll-116. Collins FS, Ponder BA, Seizinger BR, Epstein CJ (1989): Editorial: The von Recklinghausen Neurofibromatosisregion on chromosome 17genetic and physical maps come into focus. Am J Hum Genet 44:l5. Edwards JH, Huson S, Ponder B (1988): Neurofibromatosis. Lancet 2:330. Fain PR, Barker DR, Goldgar DE, Wright E, Nguyen K, Johnson CJ, Kivlin J, Willard H, Mathew C, Ponder B, Skolnick M (1987): Genetic analysis of NF1: identification of close flanking markers on chromosome 17. Genomics 4:340-345. Fain PR, Goldgar DE, Wallace MR, Collins FS, Wright E, Nguyen K, Barker DF (1989): Refinedphysical and genetic mapping ofthe NF1 region on chromosome 17. Am J Hum Genet 45:721-728. Francke U, Ochs HD, De Martinville B, Giacalone J , Lindgren V, Disteche C, Pagon RA, Hofker MH, van Ommen G-JB, Pearson PL, Wedgwood RJ (1985): Minor Xp21 chromosome deletion in a male associated with expression of Duchenne muscular dystrophy, chronic granulomatous disease, retinitis pigmentosa, and McLeod syndrome. Am J Hum Genet 37:250-267. Goldgar DE, Green P, Parry DM, Mulvihill JJ (1989): Multipoint linkage analysis in neurofibromatosis type I: a n international collaboration. Am J Hum Gen 44:6-12. Hook ED (1975): The XYY genotype. Science 189:1044-1045. Korenberg JR, Pulst SM, Neve RL, West R (1989): The Alzheimer amyloid precursor protein maps to human chromosome 21 bands q21.105-q21.05. Genomics 5:124-127. Pulst SM, Graham JM, Fain P, Barker D, Pribyl T, Korenberg J R (1990): The achondroplasia gene is not linked to the locus for neurofibromatosis 1 on chromosome 17. Hum Genet 85:12-14. Schwartz DA, Cantor CR (1984):Separation of yeast-chromosome-sized DNA by pulsed field gradient gel electrophoresis. Cell 49:589-594. Seizinger BR, Rouleau GA, Ozelius LJ,Lane AH, Faryniarz AG, Chao MV, Huson S, Korf BR, Parry DM, Pericak-Vance MA, Collins FS, Hobbs WJ, Falcone BG, Lannazzi JA, Roy JC, St George-HyslopPH, Tanzi RE, Bothwell MA, Upadhyaya M, Harper P, Goldstein AE, Hoover DL, Bader JL, Spence MA, Mulvihill J J , Aylsworth AS, Vance JM, Rossenwasser G, Gaskell PC, Roses AD, Martuza RL, Breakefield XO, Gusella JF (1987): Genetic linkage of von Recklinghausen Neurofibromatosis to the nerve growth factor receptor gene. Cell 49:589-594.
Neurofibromatosis and Achondroplasia Stephens K, Green P, Riccardi V, Ng S, Rising M, Barker D, Darby JK, Falls KM, Collins FS, Willard HF, Donis-Keller H (1989):Genetic analysis of eight loci tightly linked to neurofibromatosis 1. Am J Hum Genet 44:13-19. Wassman ER, Kovacks B, Rimoin DL, Sparkes R, Alfi 0 (1988):Achon-
87
droplasia, neurofibromatosis, and 47,XYY as new mutational events in a single individual. Am J Med Genet (Suppl) 43:A99. White R,Nakamura y,OConnell, Leppert M, ~ ~JM, Barker l D,~ Goldgar D, Skolnick M, Carey J, Wallis CE, Slater CP, Mathew C, Ponder B (1987):Tightly linked markers for the neurofibromatosis type 1 gene. Genomics 1:364-367.
~
