GENOMICS

9,

407-419

(1991)

A Genetic Linkage Map of 27 Markers MICHAEL

B. PETERSEN,*-’ ARAVINDA

*Center for Medical

on Human Chromosome

SUSAN A. bUGENHAUPT,t” JOHN CHAKRAVARTI, t$ AND STYLIANOS

G. LEWIS,* ANDREW E. ANTONARAKIS**~

21

C. WARREN,***

Genetics and Departments of *Pediatrics and *Psychiatry, The Johns Hopkins University School of Medicine, Baltimore, Maryland 21205; and Departments of tHuman Genetics and .$Psychiatry, University of Pittsburgh, Pittsburgh, Pennsylvania 1526 1 Received

July 19, 1990

A number of investigations have been directed toward the mapping of the acrocentric chromosome 21, the smallest of the human chromosomes. This chromosome contains genes involved in two major human disorders. Down syndrome, the most common genetic cause of mental retardation, is usually caused by trisomy 21. Recently, a critical region for Down syndrome has been delineated on chromosome 21, and proposed to contain genes responsible for most of the major symptoms involved in this phenotype (Korenberg et al., 1988, 1989; McCormick et al., 1989; Rahmani et al., 1989). A familial form of Alzheimer disease, the most common cause of dementia in the elderly, has been mapped to chromosome 21 in some pedigrees (St. George-Hyslop et al., 1987; Goate et al., 1989), but not in other kindreds (Roses et al., 1988; Schellenberg et al., 1988). A detailed linkage map of chromosome 21 will help to clarify the mapping of Alzheimer disease to chromosome 21, lead to further characterization of the chromosomal region involved in Down syndrome, and elucidate the role of recombination in nondisjunction leading to Down syndrome (Warren et al., 1987; Meijer et al., 1989). Several gene maps for human chromosome 21 have been reported and include macrorestriction fragment physical maps using somatic cell hybrids (Van Keuren et al., 1986; Gardiner et al., 1988, 1990; Owen et al., 1990) and radiation hybrids (Cox et al., 1988; Burmeister et al., 1989, 1990). A genetic linkage map of chromosome 21 with 15 DNA markers was constructed (using a large Venezuelan kindred) by Tanzi et al. (1988). We have previously described a genetic linkage map of 17 DNA markers using the 40 CEPH (Centre d’Etude du Polymorphisme Humain) reference families (Warren et al., 1989). In this paper we present a new and updated version of a linkage map of human chromosome 21, now comprising 27 markers, including 10 genes and 17 anonymous sequences. This genetic map has given an average resolution of 6 CM between adjacent markers and provides a greater

We have constructed a genetic linkage map of the long arm of human chromosome 21 comprising 27 DNA markers. This map is an updated version of that reported earlier by our group (1989, Genomics 4: 579-591), which contained 17 DNA markers. The current markers consist of 10 genes and 17 anonymous sequences. Traditional methods (restriction fragment length polymorphisms) were used to map 25 of these markers, whereas 2 markers were studied by polymerase chain reaction amplification of (GT), dinucleotide repeats. Linkage analysis was performed on 40 CEPH families using the computer program packages LINKAGE, CRI-MAP, and MAPMAKER. Recombination rates were significantly different between the sexes, with the male map being 132 CM and the female map being 161 CM, assuming Kosambi interference and a variable ratio of sex difference in recombination. Approximately one-half of the crossovers in either sex occur distally, in terminal band 21q22.3, which also contains 16 of the markers studied. The average distance between adjacent markers was 6 CM. ICI lssl Academic PRSS, IX.

INTRODUCTION

A large effort is now being directed at constructing comprehensive genetic linkage maps of each chromosome. Such maps will facilitate the identification and genetic mapping of the genes involved in monogenic diseasesand the genes involved in multifactorial disorders. Furthermore, genetic maps have great utility in carrier detection and prenatal diagnosis of hereditary disorders. A detailed linkage map is also a prerequisite for the eventual DNA sequencing of the entire chromosome.

’ The first two authors have made comparable contributions to this project. ’ To whom correspondence should be addressed at the Center for Medical Genetics, CMSC 10-111, The Johns Hopkins Hospital, 600 N. Wolfe Street, Baltimore, MD 21205. 407

Copyright All

rights

I APP PFKL CD18 D”lS113 HMGl4 Note.

See text

411

MAP

Map

map

~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ I 1 1 1 1 1 1

2(119) 1

2(273) 2f7) 1

1 2(24)

1

ml

2(58)

1 1 1 2(2)

1 2(14) 2(13)

2(336)

1

for details.

1OOO:lof the most likely location. The likely locations are ranked as 1,2,3, * * . in order of decreasing likelihood; the numerical value in parentheses indicates the odds by which the indicated rank is worse than the most likely position. These results imply that 6 of these loci, D21S15, D21S17, D21S42, D21S55, D21S58, and DZlSllO, can be mapped to a unique interval with odds greater than 1OOO:l. Furthermore, if those locations with odds 1OO:l or greater are considered as definitive, then 3 additional loci, D2lS3, D21Sll1, and PFKL, also have unique locations. The 7 remaining loci have locations in two segments with odds lessthan 1OO:l. Note that of the 9 loci that can be mapped to a single interval on the anchor map, the interval D21S82-D21S156 contains the 4 loci D21S3, D21S17, D21S55, and D21S58. Thus, the most likely locus order for the 20 mapped markers is (D21S13, D21S16) - D21SllO - D21Sl/ D21Sll - D21S8 D21Slll(SODl, D21S82) - (D21S3, D21S17, D21S55, D21S58) - D21S156 - D21S15 - MXl D21S42-CRYAl-PFKL-COL6Al. We call this map the reference map. The remaining loci were mapped with respect to specific selections of markers from the reference map. The loci D21S3, D21S17, D21S55, and D21S58 were mapped with respect to D21Slll-D21S82-D21S156. The most likely order was D2lSlll-D21S82D21S58-D21S17-D21S55-D21S3-D2lSl56 and was 81 times more likely than the next most likely order obtained by inverting D21S17 and D21S58. The locus APP was mapped relative to D21SllO-D21Sl/ D21Sll-D21S8-D21Slll-D2lS82; APP was localized between D21S8 and D21Slll with odds greater than 1OOO:l. Similarly, both ETS2 and HMG14 were

mapped relative to D21S55 - D21S3 - DZlS156 D21S15. The most likely order was D21S55-ETS2D21S3-D21S156-HMG14-D2lSl5 and was 282 times more likely than the order obtained by inverting the locations of D21S3 and D21S156. Subsequently, D21S112 and D21S113 were mapped relative to MXl-D21S42-CRYAl-PFKL-COLGAl. The most likely order, placing D21S113 between CRYAl and PFKL and placing D21S112 between PFKL and COLGAl, was 1000 times greater than the next most likely order. BCEI was placed between MXl and D21S42 with odds of 112:l versus the order MXlD21S42-BCEI. The most likely position for CD18 was between D21S113 and PFKL but with odds of only 3:l versus the order D21S113-PFKL-CD18. The above results were used to produce a comprehensive map that included all the 27 marker loci. This locus order is presented in Fig. 1. As a final validation we tested this final order by evaluating the log,, likelihood difference by inverting each adjacent locus pair but retaining the order of the remaining loci. These log,, odds are also provided in Fig. 1 and are generally 1OO:l or greater, except for the locus pairs D21S58D21S17, ETS2-D21S3, D21S156-HMG14, and BCEI-D21S42. However, the order indicated in Fig. 1 is the most likely map based on the genetic marker data. Evidence for the position of loci ETSB, HMG14, andD21S156 relative to D21S3 is provided from studies with hamster-human hybrid cell line R2-10 (Van Keuren et al., 1986; Wong et al., 1989), which contains human chromosome 21 except loci distal to D21S3. Using PCR amplification or Southern blot hybridization, ETS2 and D21S156 map proximal to D21S3 (Warren et al., 1989; Lewis et al., 1990) and HMG14

412

PETERSEN

log,0

/

DZISIJ

3.74 D2lSl

IO

9 08 02151

/

D2lSll

15.66 D21S8 3.81 APP 5 03 D2lSlll 4.82 021582

/

so01

13.74 021SS8 I 97 “2151‘ 4.44 D21555 1327 ET52 I 14 02153 2 45 0215156 0 57 HtlG14 9 53 32!ili 10.75 MXI 7 I8 BCEI I 72 02,542 2.03 CRYAl 7.13 02151 8.5

I3

I CD18

0 48 PFKL 7 08 021‘1 29

AL.

ence was recomputed by dividing the comprehensive map into a proximal (D21S13-D21S58) and distal (D21S17-COL6Al) map. The x2 value for this test was 39.33 (7 df, P < 10e4) for the proximal map and 31.31 (15 df, 0.005 < P < 0.01) for the distal map. The sex-difference test is significant in both cases, but this difference is more marked in the proximal region. Table 4 also provides the estimated recombination values under the assumption of an interference level of 0.35, as estimated from chiasma counts of human male meioses (Rao et al., 1977) and calculated by multiple pairwise analysis (Morton and Andrews, 1989). As expected, t,hese values are smaller than those under the Haldane map function (interference level of 1.0). The total length of the genetic linkage map was estimated under the Haldane and Kosambi map functions as described in Warren et al. (1989). We have also estimated the total map length under the Rao map function (Rao et al., 1977) and an interference level of 0.35 according to the methods of Morton and Andrews (1989). The estimated values are provided in Table 5 and show a wide range. Specifically, the length under the Haldane map function is about two times that under the Rao map function with p = 0.35. One should note, however, that the method of esti-

Loci 021516

ET

IL

80 COL6A

I

FIG. 1. Most likely order of 27 markers on human chromosome 21 with odds against the permutation of adjacent loci.

TABLE Estimates

4

of Recombination

Value

in %

Interference

distal to D21S3 (Petersen et al., 1990a). This result supports the order ETS2-D21S156-D21S3-HMG14, which is the second best order for the linkage map. Recombination Map Length

Frequency,

Sex Difference.

p = 1.0 Locus

and Total

The final comprehensive map was used to estimate the recombination frequency of each interval by multipoint analysis and assuming no interference. Table 4 provides the maximum likelihood estimates of recombination value under the assumption of no sex difference (0,=,) and sex difference (fI,, (I,), respectively. The first three columns are the estimates when the Haldane map function was used. These data were also used to calculate the log,, likelihood of the map when sex difference in recombination was absent (-876.58) and when it was present (-859.80). The x2 value for the test of no sex difference in recombination was 77.27 (23 df, P < 10e4) and is highly significant. Inspection of the values, as also plotted on the chromosome 21 idiogram in Fig. 2, suggests that most of the sex difference is localized to the proximal onethird of the linkage map. To localize this sex difference further, the log,, likelihood test for sex differ-

D21S110 DBlSl/D21Sll D21S8 APP D”lS111 D21S82. SOD1 D”lS58 D21S17 D”lS55 ETSB D”lS3 D21S156 HMG14 D‘21S1.5 MXl RCEI D”lS42 CRYAI D21Sl I:3 CD18 PFKL D21S118 COL6Al

fl,=f

(I, 4 1

9 2 6 4 4 2 I6 8 1 3 4 10 4 7 6 2 5 4 2 7 18

p 7 0.35 f’f

ii,:,

Hrn

4

CHROMOSOME DZlS16 DZiS13

DZlSllO

DZlSl

iDZlSl1

DZl SS

DZlS82

/ SOD1

q -J-

-’

22 1

D21S15

013 1

Oo5 t n nq

‘Llo2’ male

MXl BCEI D21S42

COLSAl

female

FIG. 2. Genetic linkage map of human chromosome 21 in males and females (Haldane map function, variable ratio in recombination between males and females). Recombination values between loci are indicated. Physical locations are shown for selected markers.

map distances under p = 0.35 is different from that for the Haldane (p = 1.0) and the Kosambi (p = 0.5) map functions.

mating

DISCUSSION

The present map of 27 markers on chromosome 21 covers 158 CM on the sex-averaged genetic map (Haldane function). This is considerably longer than our first version of the map with 17 markers (Warren et al., 1989), where the total length was estimated at 136 CM. No markers further centromeric or telomeric have been added; however, the placement of 10 additional markers between previous loci allowed the detection of additional recombination events. The order of the 17 previously reported markers is conserved in t,he present map, except for BCEI, the position of which has moved more proximally and is no longer the most distal marker in the map. However, the odds for the placement of BCEI were low in the previous map (Warren et al., 1989). Recombination is significantly higher in female meioses as described previously for chromosome 21

21 LINKAGE

MAP

413

(Tanzi et al., 1988; Warren et al., 1989) and observed for essentially every chromosome (Donis-Keller et al., 1987). The sex difference is due to a variable ratio of recombination along the chromosome, and not a const,ant

ratio

specific

for the

individual

chromosome.

Not every interval between two loci shows a significant difference, as also observed in detailed linkage maps of chromosomes 7 (Lathrop et al., 1989) and 10 (Bowden et al., 1989). The total length of the genetic map of human chromosome 21 is calculated to be 143 CM in males and 182 CM in females (Table 5), assuming no chiasma interference (Haldane function). With the assumption of a moderate level of interference (Kosambi function), the estimated total map lengths are about 10% smaller, 132 and 161 CM in males and females, respectively (Table 5). These are considerably larger than the estimate from meiotic chiasma counts on 21q (Laurie and Hultbn, 1985), where a mean chiasma frequency of 1.05 from seven karyotypically normal males corresponds to a map length of 53 CM. The present map shares 12 markers in common with that of Tanzi et al. (1988), who reported a linkage map of 15 markers with total map length of 50 CM in males and 126 CM in females. The two maps agree on the order of the markers in common. The two maps are not comparable regarding the total map length, as they do not share the most telomeric marker and as the addition of more markers can allow the detection of more recombination events. More than half the crossovers in either sex occur distally, in terminal band 21q22.3, which also contains 16 of the markers studied (including the genes ETSS, HMG14, MXl, BCEI, CRYAl, CD18, PFKL, and COLGAl), but account,s for only about 15% of the physical length of this chromosome. This is in agreement with the findings of Tanzi et al. (1988) and the observed chiasma distribution of meiosis (Laurie and Hultkn, 1985). In the physical map of chromosome 21 by Gardiner et nl. (1990), region q22.3 contains a large fraction of chromosome 21 genes identified to date, as 9/22 expressed sequences examined are clustered within 4% of the chromosome. TABLE Chromosome

5

21 Linkage Map Lengths under Different Assumptions

(in CM & SD)

Map function Haldane (p = 1.0)

Kosambi

Rao

Sex difference

(p = 0.5)

(p = 0.35)

None

158

144

Variable ratio Males Females

143 + 55 IFi2 * 52

f 44

i

41

132 + 50 161 * 46

83 2 3

72 * 3 95 * 5

414

PETERSEN

The linkage map presented here covers most of the entire long arm of chromosome 21. From physical mapping data, the most proximally located known locus on 21q is D21S16 (Gardiner et al., 1990; Owen et al., 1990). The most distal locus in our linkage map is the COL6Al gene. Pulsed-field gel electrophoresis (PFGE) using a yeast artificial chromosome (YAC) with the telomere of chromosome 21 has estimated the COL6Al gene to be 600 kb from the telomere (Burmeister et al., 1990). The most telomeric known locus is the SlOOB gene (Allore et al., 1988), which by PFGE has been shown to be approximately 200 kb from the telomere (Burmeister et al., 1990). We have been unable to include SlOOB in the present linkage map due to the paucity of DNA polymorphisms. The most comprehensive physical map of chromosome 21 published to date (Gardiner et al,, 1990) analyzes 52 probes by PFGE using somatic cell hybrids. The physical map shares 21 markers with the linkage map presented here, and the two maps are entirely consistent with regard to locus order. Comparison with the mouse linkage map shows a high degree of homology between the order of loci on human chromosome 21 and groups of loci on mouse chromosomes 16, 17, and 10 (Reeves et al., 1989). In this way loci SlOOB, COLGAI, CD18 (MacDonald et al., 1988), and PFKL (R. Reeves, personal communication) are on mouse chromosome 10, whereas CRYAl is on mouse chromosome 17 (Skow and Donner, 1985). Further evidence for a close linkage between CD18 and PFKL is suggested by their co-occurrence on the same 50-kb SstII fragment after PFGE (M. McGinniss, personal communication). Two of the markers in the present map (HMG14 and D2lSl56) were analyzed through a (GT), repeat polymorphism, using PCR with primers flanking the repeat (Petersen et al., 1990a; Lewis et al., 1990). Both markers showed multiallelic VNDRs and observed

Loci 17

I

17 17 17 17 17

2 3 4 5 6 7 8 9 10

17

17 17 17

e

2

0.44 0.50 0.47 0.15 0.38

0.05 0.00 0.01 11.85

0.10

0.07 0.14 0.19

0.50

0.45 1.00 19.69

4.18 2.03 0.00

4

0.32 0.50 0.50 0.08 0.30 0.10 0.02

L

0.50 0.48 0.42 0.18 0.43

0.15

0.10 0.11 0.13

0.21 0.23

0.18 0.50

ET

heterozygosity of 0.58 and 0.76, respectively. Dinucleotide repeats represent an abundant class of DNA polymorphisms in the human genome and are therefore useful for linkage studies (Tautz, 1989; Weber and May, 1989; Litt and Luty, 1989). Individuals can be genotyped more rapidly by the PCR method (Saiki et al., 1985) than by traditional blotting and hybridization methods (Southern, 1975). In addition, PCR amplification of VNTRs (Jeffreys et al., 1988; Boerwinkle et al., 1989; Ludwig et al., 1989) and polymorphisms of other types of short repeats as in the poly(A) tracts of Alu repeated sequences (Economou et al., 1990) will facilitate mapping of the human genome and the localization of disease-related markers. In conclusion, the present genetic linkage map of human chromosome 21 comprising 27 markers gives an average resolution of 6 CM between adjacent markers and provides a greater than 90% probability for localizing any gene or marker to this chromosome.

APPENDIX The following is a listing of the results of the linkage analysis of all new pairwise comparisons of the 26 loci studied. The earlier comparisons are provided in Warren et al. (1989). The locus numbers are as in Table 1. i = maximum likelihood estimate (MLE) of recombination value (0) assuming no sex difference -8, = MLE of H in females 0, = MLE of 0 in males ,Z?= maximum lod score assuming no sex difference in B i,,, = maximum lod score assuming sex difference in H Asterisk

0.01

0.07 12.33" 0.69 1.00 20.69* 4.19*

2.03 0.34

(*) denotes i or ,Z?m,r> 3.0

Loci

-cn,f

0.35

AL.

17 17 17 17 17 17 18 18 18 18

ri 11

0.10

12 13 14 15 16 7 2 3 4

0.13 0.38 0.27 0.02 0.50 0.50 0.43 0.39 0.16

2

e,

e,

-%ll,f

6.02 15.30

0.17 0.16 0.23 0.04 0.50 0.38 0.47 0.40

0.05 0.10 0.46 0.35 0.00 0.43 0.50 0.38 0.37

6.38* 15.45* 1.67 5.42* 17.52* 0.00 0.02 0.61 0.47

0.13

0.18

13.93*

0.81

4.57 17.25 0.00 0.00 0.43 0.47 13.80

0.19

416

PETERSEN

ET

AL.

APPENDIX-Continued e

Loci 23

23 23 23 23 23 23 24 “4 24 24 24 24 24 24 24 24 23 24 24 “4 24 24 24 24 24 24 24 24 24 25 25 25 2F, “5 ‘25 2.5 25 25 25

16 17 18 19 20 21 22 1 a 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 ‘12 23 1 2 3 4 5 6 7 8 9 10

0.50 0.03 0.03

0.14 0.07 0.12 0.50 0.50 0.42 0.39 0.20 0.50 0.09 0.14 0.32 0.18 0.46 0.29 0.28 0.40 0.37 0.18 0.46 0.10 0.05 0.21 0.17 0.18 0.38 0.09 0.28 0.39 0.29 0.03 0.26 0.20 0.22 0.14 0.18 0.18

2 0.00

14.13 14.13 3.01 16.55 5.97 0.00 0.00 0.10 0.53 0.73 0.00 4.67 11.48 0.39 2.79 0.00 3.24 3.40 0.64 1.28 5.91 0.06 10.46 18.61 4.37 11.08 4.64 0.21 8.57 2.63 0.70 2.93 23.41 2.46 1.31 6.79 4.75 3.07 0.40 -

e, 0.50 0.00 0.03 0.10

0.04 0.19 0.50 0.50 0.44 0.24 0.21 050 0.19 0.09 0.34 0.21 o.:i:j 0.18 0.23 Cl.40 0.33 0.14 0.50 0.05 0.03 0.21 0.13 0.18 0.48 0.12 0.29 0.50 0.38 0.00 0.31 0.00 0.25 0.15 0.28 0.26

e, 0.50 0.05 0.03 0.20 0.08 0.00 0.50 0.43 0.39 0.50 0.19 0.41 0.00 0.18 0.29 0.12 0.49 0.39 o.:iF, 0.39 0.40 0.25 0.38 0.12 0.07 0.21 0.21 0.18 0.37 0.04 0.28 0.3 1 0.21 0.05 0.24 0.21 0.21 0.13 0.09 0.00

2

.zm.f 0.00

14.42* 14.1:3* :3.14* 16.77* 7.34* 0.00 0.09 0.13 1.57 7.46* 0.12 5.07* 11.93” 0.40 2.88 0.02 4.42” 3 .8‘S* r 0.64 1.31 6.22* 0.39 10.66* 18.75* 4.37* 11.:$8” 4.64* 0.24 8.81” 2.63 I .76 3.55” 24.22* 2.55 1.48 6.83* 4.76* 3.58* 0.76

25 25 25 25 25 25 25 “5 25 ‘5 ‘5 25 25 ‘5 “6 26 26 26 “6 ‘6 26 26 ‘6 ‘6 26 26 26 26 26 26 26 26 26 “6 26 26 26 26 26

0.01

30.83

0.28 0.26 0.19 0.19 0.34 0.09 I). 13 0.14 0.15 0.19 0.42 0.15 0.21 0.34 0.31 0.20 0.02 0.22 0.23 0.19 0.08 0.11 0.22 0.01 0.21 0.28 0.17 0.17 0.30 0.10 0.15 0.08 0.08 0.05 0.47 0.11 0.16 0.01

3.63 3.29 10.99 5.66 1.39 13.14 15.04 7.99 17.02 4.41 0.15 4.56 7.70 0.73 2.26 9.05 48.43 5.37 1.47 9.92 12.77 8.29 0.61 40.77 10.47 2.68 17.29 8.03 1.81 15.83 15.54 18.53 37.2” 30.67 0.00 15.35 12.80 48.25

0.01 0.33

0.28 0.18 0.26 0.48 0.04 0.11 0.19 0.22 0.09 0.10 0.1:3 0.20 0.40 0.:39 0.22 0.02 0.33 0.40 0.18 0.12 0.14 0.10 0.0” 0.21 0.32 0.17 0.19 0.44 0.12 0.17 0.10 0.13 0.04 0.50 0.12 0.18 0.00

H, 0.00 0.25 0.25 0.20

0.14 0.27 0.12 0.14 0.1 1 0.09 0.26 0.42 0.16 0.22 0.29 0.26 0.18 0.02 0.16 0.18 0.19 0.05 0.08 0.22 0.01 0.2’ 0.24 0.17 0.15 0.25 0.09 0.13 0.07 0.03 0.05 0.50 0.10 0.15 0.01

d

Zmf

:10.87* 3.88* 3.32* 11.oo* 6.14* 2.08 1:3.49* 15.07* 8.1:5* 18.“9* 5.:12* 0.15 4.59” 7.7‘)” 1.01 2.95 9.10” 48.43* 6.46* 1.70 9.92” 13.13* 8.44* 0.61 40.X8* 10.47* 2.89 17.29* 8.11* 2.48 15.88* 15.74* l&63* :39.31* 30.70* 0.00 15.:$8* 1”.88* 48.68*

REFERENCES

ACKNOWLEDGMENTS We thank the investigators in Table 1 for providing DNA probes or sequence information. M.B.P. was supported by the Danish Research Council and Academy, Else og Mogens Wedell-Wedellsborgs Fond, and a Fulbright Fellowship. A.C.W. was supported by a fellowship from the W. M. Keck Foundation and by the Alzheimer’s Association, A.C. by NIH Grants GM33771 and Research Career Development Award HD00774, and S.E.A. by NIH Grant HD24605. We thank L. Taylor for expert secretarial assistance.

11 12 13 14 15 16 17 18 19 “0 ‘1 “2 2:1 24 1 2 ?I 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 “0 “1 22 “3 24 “5

e,

1.

2.

ALLORE, R., O’HANLON, D., PRICE, R., NEILSON, K., WILLARD, H. F., Cox, D. R., MARKS, A.. AND DUNN, R. J. (1988). Gene encoding the /j subunit of SlOO protein is on chromosome 21: Implications for Down syndrome. Science 239: 1311-1313. HOERWINKLE, E., XIONG, W., FOUREST, E., AND CHAN, L. (1989). Rapid typing of tandemly repeated hypervariahle loci by the polymerase chain reaction: Application to the apolipo-

CHROMOSOME protein B 3’ hypervariable 86: 212-216. 13

4.

5.

6.

7.

8.

9.

10.

Il.

12.

region.

Proc. Natl.

Sci. 1JSA

BOWDEN, D. W., GRAVIUS, T. C., GREEN, P., FALLS, K., WURSTER-HILL, D., NOLL, W., MILLER-KAHLE, H., AND DONISKELLER, H. (1989). A genetic linkage map of 32 loci on human chromosome 10. Genomics 5: 718-726. BURMEISTER, M., KIM, S. W., DELANGE, T., TANTRAVAHI, LT.. FRAZIER, K., Cox, D. R., AND MYERS, R. M. (1989). The fine structure map of the distal long arm of chromosome 21: Hot spots of recombination and homology to several mouse chromosomes. Amer. J. Hum. Genet. 45: A133. BURMEISTER, M., KIM, S., PRICE, E. R., DELANGE, T., TAN~RAVAHI, U., MYERS, R. M., AND Cox, D. R. (1990). Map of the distal region of the long arm of human chromosome 21 constructed by radiation hybrid mapping and pulsed field gel electrophoresis. Submitted for publication. Cox, D. R., PRICE, E. R., BURMEISTER, M., SHEFFIELD, V., MURRAY, C., UGLUM, E., AND MYERS, R. M. (1988). Fine structure genetic analysis of human chromosome 21 using radiation hybrid mapping. Amer. J. Hum. Genet. 43: A141. DAUSSET, J., CANN, H., COHEN, D., LATHROP, M., LALOUEL, J.-M., AND WHITE, R. (1990). Centre d’Etude du Polymorphisme Humain (CEPH): Collaborative genetic mapping of the human genome. Genomics 6: 575-577. DONIS-KELLER, H., GREEN, P., HELMS, C., CARTINHOUR, S., WEIFFENBACH, B.. STEPHENS, K., KEITH, T. P., BOWDEN, D. W., SMITH, D. R., LANDER, E. S., BOTSTEIN, D., AKOTS, G., REDIKER, K. S., GRAVIUS, T., BROWN, V. A., RISING, M. B., PARKER, C., POWERS, J. A., WATT, D. E., KAUFFMAN, E. R., BRICKER, A., PHIPPS, P., MULLER-KAHLE, H., FULTON, T. R., No, S., SCHUMM, J. W., BRAMAN, J. C., KNOWLTON, R. G., BARKER, D. F., CROOKS, S. M., LINCOLN, S. E., DALY, M. J., ANDABRAHAMSON, J. (1987). A genetic linkage map of the human genome. Cell 51: 3 19-337. ECONOMOU, E. P., BERGEN, A. W., WARREN, A. C., AND ANTONARAKIS, S. E. (1990). The polydeoxyadenylate tract of Alu repetitive elements is polymorphic in the human genome. Proc. Natl. Acad. Sci. 1JSA 87: 2951-2954. GARDINER, K., HORISBERGER, M., KRAUS, J., TANTRAVAHI, U.. KORENBERG. J., RAO, V., REDDY, S., AND PATTERSON, D. (1990). Analysis of human chromosome 21: Correlation of physical and cytogenetic maps; gene and CpG island distributions. EMRO J. 9: 25-34. GARDINER, K., WATKINS, P., Mij~k;~, M., DRABKIN, H., JONES, C., AND PATTERSON, D. (1988). Partial physical map of human chromosome 21. Somat. Cell Mol. Genet. 14: 62% 637. GOATE, JAMES, SOR, M. disposing Lancet

A. M., HAYNES, A. R., OWEN, M. L. A., LAI, L. Y. C., MULLAN, M. J., N.: WILLIAMSON, R., AND HARDY, locus for Alzheimer’s disease on 1: X52-355.

13.

HALDANE, J. B. S. (1919). The combination and the calculation of distances between factors. J. Genet. 8: 299-309.

14.

HAMADA, H., PETRINO, M. G.. novel repeated element with widely found in evolut.ionarily Proc. Natl. Arad. Sci. USA 79:

15.

Acad.

J., FARRALL, M., ROQUES, P., RosJ. A. (1989). Prechromosome 21. of linkage values, the loci of linked

AND KAKUNAGA, T. (1982). A Z-DNA-forming potential is diverse eukaryotic genomes. 6465-6469.

HORISBER~ER, M. A., WATHELET, M., SZPIRER, J., SZPIRER, C., ISLAM, Q., LEVAN, G., HUEZ, G., AND CONTENT, J. (1988). cDNA cloning and assignment to chromosome 21 of IFI-78K gene, the human equivalent of murine Mx gene. Somat Cell Mol. &net. 14: 123-131.

21 LINKAGE

417

MAP

16.

JAWORSKI, C. J., AND PIATIGORSKY, in the functional human cuA-crystallin 337: 752-754.

17.

JEFFREYS, A. J., WILSON, V., NEUMANN, R., AND KEYTE, J. (1988). Amplification of human minisatellites by the polymerase chain reaction: Towards DNA fingerprinting of single cells. Nucleic Acids Res. 16: 10953-10971. KISHIMOTO, T. K., O’CONNOR, K., LEE, A., ROBERTS, T. M., AND SPRINGER, T. A. (1987). Cloning of the fi subunit of the leukocyte adhesion proteins: Homology to an extracellular matrix receptor defines a novel supergene family. Cell 48: 681-690. KORENBERG, J. R., CROYLE, M. L., AND COX, D. R. (1987). Isolation and regional mapping of DNA sequences unique to human chromosome 21. Amer. J. Hum. Genet. 41: 963-978.

18.

19.

20.

21.

22.

J. (1989). A pseudo-exon gene. Nature (London)

KORENBERG, J. R., KOJIS, T. L., BRADLEY, C.. AND DISTECHE, C. (1989). Down syndrome and band 21q22.2: Molecular definition of the phenotype. Amer. J. Hum. Genet. 45: A79. KORENBERG, .J. R., PULST, S. M., KAWASHIMA, H.. IKEUCHI, T., YAMAMOTO, K., OGASAWARA, N., SCHONBERG, S. A., WEST, R., KOJIS, T., AND EPSTEIN, C. ,J. (1988). Familial Down syndrome with normal karyotype: Molecular definition of the region. Amer. J. Hum. Genet. 43: AllO. KOSAMBI, D. D. (1944). The estimation of map distances from recombination values. Ann. Eugen. 12: 172-175.

23.

LANDER, E. S.. GREEN, P.. ABRAHAMSON, J., BARLOW, A., DALY, M. d., LINCOLN, S. E., AND NEWBURO, L. (1987). MAPMAKER: An interactive computer package for constructing primary genetic linkage maps of experimental and natural populations. Genomics 1: 174-181.

24.

LANDSMAN, D., MCBRIDE, 0. W., SOARES, N.. CRIPPA, M. P., SRIKANTHA, T.. AND BUSTIN, M. (1989). Chromosomal protein HMG-14: Identification, characterization, and chromosome localization of a functional gene from the large human multigene family. J. Biol. Chem. 264: 3421-3427.

25.

LATHROP, G. M., AND LAI,OUEL, J.-M. (1988). Efficient computations in multilocus linkage analysis. Amer. J. Hum. &net. 42: 498-505.

26.

LATHROP, G. M.. NAKAMURA, Y., CARTWRIGHT, I’., O’CONNELL, P., LEPPERT, M., JONES, C., TATEISHI, H., BRAGG, T., LALOUEL, J-M., AND WHITE, R. (1988). A primary genetic map of markers for human chromosome IO. Genomics 2: 1~7~ 164.

27.

LATHROP, G. M., O’CONNELL, P., LEPPERT, M., NAKAMURA, Y., FARRALL, M.. TSUI, L.-C., LALOCJEL, J.-M., AND WHITE, R. (1989). Twenty-five loci form a continuous linkage map of markers for human chromosome 7. Genomics 5: 866-873.

28.

LAURIE, D. A., AND HULTJ?N, M. A. (1985). Further studies on bivalent chiasma frequency in human males with normal karyotypes. Ann. Hum. Genet. 49: 189-201.

29.

LEWIS, J. G., WEBER, J. L.. PETERSEN, M. B., SLAU~:BNHAUPT, S. A., KWITEK, A., MAY, P. E., WARREN, A. C., CHAKRAVARTI, A., AND ANTONARAKIS, S. E. (1990). Linkage mapping of the highly informative DNA marker D21S156 to human chromosome 21 using a polymorphic GT dinucleotide repeat. Genomics 8, 400-402.

30.

LITT, M., AND LUTY, J. A. (1989). A hypervariable microsatellite revealed by in vitro amplification of a dinucleotide repeat within the cardiac muscle actin gene. Amer. J. Hum. Genet. 44: 397-401.

31.

LUDWIG, E. H.. FRIEDL, High-resolution analysis

W., AND MCCARTHY, B. J. (1989). of a hypervariable region in the hu-

418

PETERSEN man 464.

32.

33.

apolipoprotein

B gene. Amw.

J. Hum.

Genet.

45: 45%

MACDONALD, G. P.. PRICE, E. It., CHU, M.-I,., TIMPL, R., ALLORE, R.. MARKS, A., DUNN, R., AND Cox, D. R. (1988). Assignment of four human chromosome 21 genes to mouse chromosome 10: Implications for mouse models of Down syndrome. Amer. J. Hum. &net. 43: A151. MARLIN, S. D., MORTON, C’. C., ANDERSON, 1). C., AND SPRINGER, T. A. (1986). LFA-1 immunodeficiency disease: Definition of the genet.ic defect. and chromosomal mapping of