Possible Genetic Predisposition to Idiopathic Focal Segmental Glomerulosclerosis

Possible Genetic Predisposition to Idiopathic Focal Segmental Glomerulosclerosis Daniel Glicklich, MD, Lloyd Haskell, MD, David Senitzer, PhD, and Robert A. Weiss, MD • HLA-A, B, and DR antigen frequencies were studied in a group of 57 patients to determine possible inborn susceptibility to idiopathic focal segmental glomerulosclerosis (FSGS). There were 34 white patients and 23 black patients, most of whom had nephrotic syndrome and later developed renal failure. HLA-DR4 was significantly increased. in both patient groups when compared with their respective control groups. This association has not been previously reported. Of note, the association with DR4 was most striking in patients with adult onset disease (in blacks, relative risk equals 5.2; In whites, relative risk equals 5.8). No other antigen was increased in both patient groups but HLA-A28 was increased in blacks. These data support the notion of genetic predisposition to focal segmental glomerulosclerosis in two different ethnic groups. © 1988 by the National Kidney Foundation, Inc. INDEX WORDS: Focal glomerulosclerosis; HLA typing.

I

DIOPATHIC focal segmental glomerulosclerosis (FSGS) is a histologically well-defined disease associated with proteinuria and often progression to end-stage renal disease (ESRD). The clinical course may be quite different in children and adults. I The etiology and pathogenesis of idiopathic FSGS are unknown. However, a number of observations suggest that genetic factors may play an important role in human and experimental FSGS.2·1O In the present study, HLA-A, B, and DR antigens were analyzed to determine a possible genetic predisposition to developing idiopathic FSGS in both white and black individuals. The results showed that HLA-DR4 was significantly increased in both patient groups. Furthermore, the association of HLA-DR4 with idiopathic FSGS was most striking in patients with adult onset disease. MATERIALS AND METHODS

Patient Selection Fifty-seven patients with biopsy-proven FSGS were the subjects of this study. Fifty-four patients developed ESRD and were referred to our hospitals for transplantation over a 14-year period, from January I, 1972 to January I, 1986. During this From the Departments of Medicine and Surgery, Monteflore Medical Center of the Albert Einstein College of Medicine and the Department of Pediatrics. Jack D. Weiler Hospital of the Albert Einstein College of Medicine. Bronx, NY Presented in part before the joint session ofthe National Kidney Foundation and American Society of Nephrology. Washington, DC, December 7. 1986. Address reprint requests to Daniel Glicklich, MD, Monteflore Medical Center, III E 210th St, Bronx. NY 10467. © 1988 by the National Kidney Foundation, Inc. 0272-6386/88/1201-0003$3.00/0

26

period, 669 renal transplants were performed at our center. Three other patients are presently being followed in clinic and agreed to the phlebotomy necessary for tissue typing. Thirtyeight patients underwent renal biopsy at our hospitals and the remaining 19 patients were biopsied at 14 referral hospitals. FSGS was confirmed by review of renal biopsy slides in the great majority of cases, otherwise the original biopsy reports were reviewed. Additional clinical data was obtained from medical records. The diagnosis was established by the presence of focal and segmental glomerular scarring of part of the glomerular tuft on light microscopy. Patients were included in the study group whether or not they had mesangial proliferation on light microscopy 11 or documentation of focal immune deposits of C3 and IgM on immunofluorescence. Patients were not studied if there was only global sclerosis, if there was extensive IgA deposition seen on immunofluorescence, or if there was evidence of significant electron dense deposits on electron microscopy. The 54 patients referred for transplantation had voiding cystourethrograms as part of the routine pretransplant evaluation, which in each case showed no significant reflux. Patients were also excluded from study if there was any history of drug abuse, systemic illness known to affect the kidney such as diabetes or vasculitis, antecedent glomerulonephritis, congenital absence of one kidney, or reflux nephropathy. No patient had a familial history of renal disease. To date, 31 of the 54 patients with ESRD have received a transplant. In five of the 31 patients (16 %), the nephrotic syndrome reappeared within 6 months of transplantation, suggesting recurrent FSGS. This is similar to the rate of recurrence in other series. 8.9

HIA ryping Forty-six patients had DR typing but this was unavailable in six whites and five blacks. Whenever possible, HLA typing was repeated to update data obtained before 1982. The phenotype frequencies of the white and black patient groups were separately compared with their respective control groups. The controls were healthy adults who had donated blood at the New York (Manhattan) Blood Center. Antigen frequencies significantly different from the New York City controls were also compared with the national control data of Tiwari and Tera-

American Journal of Kidn9Y Diseases, Vol XII, No 1 (July), 1988: pp 26-30

27

HLA TYPING IN FOCAL GLOMERULOSCLEROSIS

Table 1.

Sex (M/F) Age at biopsy (yr) Nephrotic syndrome Time from biopsy to ESRD (yr)

Clinical Data

Black

White

Total

(n = 23)

(n = 34)

(n = 57)

13/10

21/13

34/23

23.9 ± 11.2'

16.7 ± 11.6

19.3 ± 11.4 52/57 4.3 ± 3.5

21/23

31/34

2.8 ± 2.2'

5.3 ± 4.3

Abbreviations: M, male, F, female. 'P < 0.025 black group compared with white group, mean ± SD. saki. 12 An antigen frequency was considered significantly different only if comparison with the initial New York City control data was confirmed by comparison with national control data. HLA-A, B, and DR antigens were determined by the standard microlymphocytotoxicity test,3 using commercially available antisera. The total number of antigens tested was 48, including 14 specifications ofHLA-A, 26 specificities ofHLA-B, and eight specificities of HLA-DR.

made, according to the method of Svejgaard et al. 14 Pc <0.025 was considered statistically significant. Relative risk (RR) was calculated as follows: RR = Pa (I - C)/C(l - Pal where Pa is the frequency of the antigen among patients and C is the frequency among control subjects.

RESULTS

Patient Characteristics

Calculations and Statistics

Clinical data for the 57 patients is summarized in Table 1. The mean age at the time of biopsy diagnosis was 19 years, with a range of 1.5 to 44 years. Nephrotic syndrome was the indication for renal biopsy in over 90 % of the cases. There was a

Statistical analysis for individual HLA antigen frequencies was carried out using the X2 test with Yate's correction. Absolute P values obtained by using a computer-based Statistical Analysis System were corrected (Pc) by multiplying by 48, which was the total number of nonindependent comparisons

Table 2.

Black Phenotype Frequencies for HLA·A and B

HLA

Patients

locus

NYC Controls

National Controls

n = 23 (%)

n = 662 (%)

n = 367 (%)

Pc' v NYC «)

Pc 2 v National «)

A1 A2 A3 A23 A26 A28 A29 A30 A31 AW33 AW34 B7 88 814 818 835 8W42 844 B45 849 850 851 8W53 8W55 8W57 8W58 8W63

13.0 39.1 8.7 13.0 4.3 34.8 13.0 8.7 8.7 17.4 17.4 17.4 8.7 13.0 13.0 30.4 8.7 17.4 8.7 4.3 4.3 4.3 21.7 4.3 13.0 8.7 4.3

8.7 34.1 16.2 16.6 5.4 17.2 6.3 21.3 3.6 9.9 6.9 19.7 8.9 5.7 7.7 21.9 7.8 12.8 6.9 6.2 2.9 5.7 14.5 0.6 10.4 4.7 2.0

6.5 27.3 14.2 20.4 7.4 16.6 12.3 28.3 4.4 9.0 12.5 17.0 5.8 8.0 7.7 12.1 14.8 13.7 7.7 4.9 1.4 2.7 12.6 1.6 7.7 20.3 0.6

NS NS NS NS NS 1.7 x 10-3 • NS NS NS NS 8 x 10-3 NS NS NS NS NS NS NS NS NS NS NS NS 1.3 x 10-3 NS NS NS

NS NS NS NS NS 7 X 10-4· NS 7.5 x 10-3 NS NS NS NS NS NS NS 1.4 x 10-5 NS NS NS NS NS NS NS NS NS NS 1.3 x 10-3

Abbreviations: NS, not significant; NYC, New York City. • Significantly different from both control groups.

28

GLlCKLICH ET AL Table 3. Patients

HLA

Locus

n = 34 (%)

A1 A2 A3 A11 A24 A26 A28 A29 A31 A32 A33 A34 B7 B8 B13 814 B15 B17 B18 827 B35 B37 B38 B39 B44 B45 B49 B50 851 BW57 BW60 BW61 BW62 BW63

23.5 64.7 29.4 8.8 17.6 11.8 8.8 8.8 2.9 2.9 2.9 2.9 23.5 14.7 2.9 2.9 2.9 5.9 5.9 2.9 20.6 2.9 5.9 2.9 35.2 2.9 8.8 5.9 8.8 5.9 5.9 5.9 11.8 2.9

White Phenotype Frequencies for HLA·A and B

NYC Controls

National Controls

n = 681 (%)

n = 1,029 (Ofo)

26.7 43.4 21.1 14.0 18.3 11.0 9.2 6.0 4.1 8.0 4.4

Pc' v NYC

25.7 46.6 26.0 12.5 12.8 7.2 9.9 8.1 6.2 7.1 3.4 0.5 18.7 17.1 5.3 9.5

20.1 14.4 4.7 10.1 7.4 9.4 8.0 7.6

Pc2 v National «)

NS NS NS NS NS NS NS NS NS NS NS

NS NS NS NS NS NS NS NS NS NS NS NS NS NS NS NS

NS NS NS NS NS NS NS NS

9.7 7.5 15.6 3.2 6.2 3.6 21.6 1.4 4.7 2.6 9.3 7.2 11.0 2.0 9.5 1.9

6.6 3.0 20.0 0.7 3.6 2.5 8.5 7.5 5.9 2.0 6.3 1.1

«)

NS NS NS NS NS NS NS NS NS NS NS NS NS NS NS NS

NS NS NS NS NS NS NS NS NS NS NS NS

Abbreviations: NS, not significant; NYC, New York City.

range of 6 months to 18 years from the time of biopsy diagnosis to the onset of kidney failure. Most patients received a combination of steroids and cytotoxic agents during the course of their illness but there was no uniform treatment regimen. Table 4. NYC National Controls HLA Blacks Controls Locus n = 18(%) n = 45 (0/0) n = 323 (%)

DR1 DR2 DR3 DR4 DRS DR6 DR7 DR8

5.5 38.9 33.3 33.3 27.8 22.2 22.2

10.4 25.0 31.8 13.6 18.1 18.1 18.1

9.6 28.5 31.6 9.6 24.8

10.2 18.6

Phenotype Frequencies Phenotype frequencies of HLA-A, B, and DR antigens in the two patient groups as well as in their respective control groups are shown in Tables 2, 3, and 4. The frequency of DR4 was signifi-

HLA·DR Frequencies for Blacks and Whites Pc'

Pc'

v NYC

National

NS NS NS

NS NS NS

9.5 x 10-6 • 3.4

NS NS NS

Abbreviations: NYC, New York City. •Significantly different from both control groups.

X

10- 12 •

NS NS NS

NYC National Whites Controls Controls n = 28 (0/0) n = 420 (%) n = 1,145 (%)

10.7 28.6 7.1 53.6

19.0 28.0

10.7

23.8 31.6 18 15.5 25.2

3.6

5.0

25.0 3.6

20.0 25.3

22.0 27.3 19.4 7.2 23.6 5.3

Pc'

Pc'

NYC

National

NS NS NS

NS NS NS

v

6.5 x 10-3 •

NS NS NS NS

4.0

X

10-5 •

NS NS NS NS

29

HLA TYPING IN FOCAL GLOMERULOSCLEROSIS

Table 5.

Differences in Frequency of DR4 According to Age at Diagnosis Patients With DR4

Age at Diagnosis (yr)

Black:

White:

2

:;518 >18 :;518 >18

4 7 8

cant!y increased in both patient groups compared with controls. No other HLA antigen was increased in both groups. DR4 was present in 33.3 % of black patients but in 13.6% of New York City controls (Pc < 0.001; RR = 3.2), and in 9.6% of national controls. DR4 was present in 53.6% of white patients but in 31.6% of New York City controls (P < 0.006; RR = 2.5), and in 27.3% of national controls. In both patient groups, the frequency of DR4 was more apparent with adult onset disease, as shown in Table 5. Patients with diagnosis after age 18 had strikingly increased frequency of DR4, 44% for blacks (Pc < 0.0001; RR = 5.1), and 73% for whites (Pc < 0.0001; RR = 5.8). However, younger patients in both groups did not have a statistically significant increased frequency of DR4. DISCUSSION

This study showed a significant increase in the phenotype frequency of HLA-DR4 in both white and black patients with idiopathic focal segmental glomerulosclerosis. This association has pot been previously reported. The association with DR4 was especially apparent in those with adult onset disease, where the relative risk was between five and six. In whites and blacks with disease of childhood onset, DR4 was also increased, but this did not reach statistical significance. It is especially noteworthy that a specific DR antigen frequency was incrased in two genetically dissimilar groups and with a similar age of onset distribution. These results are consistent with a possible genetic predisposition to this disorder. HLA-A28 was increased signficantly in blacks but not in whites. However, there was no substantial evidence of linkage disequilibrium between A28 and DR4 in the black group. There is some evidence that childhod onset FSGS has a different course, response to therapy, and prognosis than adult onset disease. I However, this remains controversial as other recent studies showed little difference between the age

Patients DR Typed

9 9 17 11

DR4 According to Age (%)

22 44 41 73

groups.IS.16 Whether FSGS in children and adults has the same etiology and pathogenesis remains unknown. With these issues in mind, our patients with DR typing were grouped into those with childhood onset and adult onset disease to determine any differences in frequency of DR4 according to age at diagnosis (Table 5). Although the numbers are small, our data suggested that adult onset disease largely accounted for the overall increase in DR4 in both blacks and whites. One might speculate that the difference in frequency of DR4 between childhood and adult onset FSGS may indicate a difference in pathogenesis. There have been only three other studies of HLA antigen frequency in FSGS. One from Germany, reported in abstract form, suggested an increased frequency of B12 in 34 patients (35 % v 22 % of controls), but it was not clear if this was a statistically significant difference. DR typing was not available. 17 A French study of 18 patients showed no significant differences in HLA-A or B antigen frequencies but DR typing was not done. IS Komori et al 19 studied 16 Japanese patients with childhood onset disease and were unable to show any difference in HLA-A, B, or DR frequencies as compared with controls. It is not entirely clear why our results differ from these previous reports but there are several possible explanations. Patient selection was quite variable in terms of age, race, and disease severity. Known racial differences in the distribution of HLA antigens may have played a role. For example, a difference in HLA antigen frequencies between white and Japanese patients with idiopathic membranous nephropathy has been shown. 20 Also, our data suggest that HLA antigen frequency may be different in childhood and adult onset FSGS. Studies of disease association with HLA antigen frequency depend heavily on patient group selection and the control group available. In this study, there was a relatively small number of patients in each group and most had nephrotic syndrome, developed ESRD, and were referred for renal trans-

30

GlICKlICH ET AL

plantation. Thus, these cases may not be representative of all patients with FSGS. Since multiple comparisons of antigen frequencies were performed with two different patient groups, there was an increased tendency of finding statistically significant differences in antigen frequencies due to chance alone. 14 Therefore, a more rigorous criteria for significance was applied. By using two control groups and requiring that an antigen frequency had to be significantly different from a local as well as national control, the results thus obtained were considered more likely to identify a phenotype of biological significance. In this manner, several antigen frequencies in the group of black patients, which were different from either New York City or national controls but not both, were excluded (Tables 2, 3, and 4).

In conclusion, we suggest that the increased frequency of HLA-DR4 in both white and black patients is evidence for genetic predisposition to idiopathic focal segmental glomerulosclerosis. This association may be important only in patients with disease onset during adulthood. Whether or not HLA-A28 in blacks may also predispose toward the disease is unknown. Further study of the genetic profile of a large number of patients with well-defined idiopathic focal segmental glomerulosclerosis is needed to clarify these observations. ACKNOWLEDGMENT The authors are gratful to Marlena Fotino, MD, of the New York Blood Center, who provided HLA antigen frequency control data, and to Leonarda B. Sablay, MD, Department of Pathology, Montefiore Medical Center, who reviewed biopsy material. Ronald Bond, PhD provided statistical assistance.

REFERENCES I. Newman J, Tisher C, McCoy R, et al: Focal glomerulosclerosis-Contrasting clinical patterns in children and adults. Medicine (Baltimore) 55:67-87, 1976 2. Weening JJ, Beukers JJB, Grond J, et al: Genetic factors in focal segmental glomerulosclerosis. Kidney Int 29:789-798, 1986 3. Walker R, Bailey RR, Lynn KL, et al: Focal glomerulosclerosis-Another familial renal disease? NZ Med J 95:686688, 1982 4. Kikuta Y, Yoshimura Y, Saito T, et al: Nephrotic syndrome with diffuse mesangial sclerosis in identical twins. J Pediatr 102:586-589, 1983 5. Trainin EB, Gomez-Leon G: HLA identity in siblings with focal glomrulosclerosis. Int J Ped Nephrol 4:59-60, 1983 6. Elema JD, Arends A: Focal and segmental glomerular hyalinosis in the rat. Lab Invest 33:554-561, 1975 7. Kreisberg 11, Karnovsky MJ: Focal glomerular sclerosis in the fawn-hooded rat. Am J Pathol 92:637-652, 1978 8. Leumann Ep, Briner J, Donckerwolcke RAM, et al: Recurrence of focal segmental glomerulosclerosis in the transplanted kidney. Nephron 25: 65-71, 1980 9. Cameron JS: Effect of the recipient's disease on the results of transplantation. Kidney Int 23:S24-533, 1983 (Suppl 14) 10. Zimmerman CE: Renal transplantation for focal segmental glomerulosclerosis. Transplantation 29: 172, 1980 II. Schoeneman MJ, Bennett B, Griefer I: The natural history of focal segmental glomerulosclerosis with and without

mesangial hypercellularity in children. Clin Nephrol 9:45-54, 1978 12. Tiwari JL, Terasaki PI: HLA and disease associations. New York, Springer-Verlag, 1985, pp 4-17 13. Minai KK, Mickey MR, Singal Dp, et al: Serotyping for hemotransplantation. XVIII. Refinement of microdroplet lymphocyte cytotoxicity test. Transplantation 6:913-927, 1968 14. Svejgaard A, Jershild C, Nielsen S, et al: HLA antigens and disease: Statistical and genetical considerations. Tissue Antigens 4:95-105, 1974 15. Cameron J5, Turner DR, Ogg CS, et al: The long-term prognosis of patients with focal segmental glomerulosclerosis. Clin NephrollO:211-218, 1978 16. Pei Y, Cattran D, Delmore T, et al: Evidence suggesting under-treatment in adults with idiopathic focal segmental glomerulosclerosis. Am J Med 82:938-944, 1987 17. Lenhard V, Muller-Wiefel DE, Dippell J, et al: HLA in minimal change nephrotic syndrome and focal segmental glomerulosclerosis. Pediatr Res 14: 1003, 1980 18. Noel LH, Des Camps B, Jungers P, et al: HLA antigen in three types of glomerulonephritis. Clin Immunol Immunopathol 10: 19-23, 1983 19. Komori K, Nose Y, Inouye H, et al: Immunogenetical study in patients with chronic glomerulonephritis. Tokai J Exp Clin Med 8:135-148, 1983 20. Hiki Y, Kobayashi Y, Itoh I, et al: Strong association of HLA-DR2 and MTI with idiopathic membranous nephropathy in Japan. Kidney Int 25:953-957, 1984