Genetic study for ossification of the spinal ligaments
Seto, N.
Nihon Geka Hokan. Archiv für Japanische Chirurgie 50(3): 461-475
1981
ISSN/ISBN: 0003-9152 PMID: 6796016 Document Number: 169168
AS (ankylosing spondylitis) and AH (ankylosing hyperostosis of the spine) are apparently of different causes, but the roentgenographic features of both diseases is marked ossification of the spinal ligaments-posterior longitudinal ligament, yellow ligament and supra-spinous ligament. Most of the reports on the subject are based on population studies, few on family studies. The causative factors of the ossification were studied genetically through family studies. In regards to AS, a genetic study was done on 3 families with emphasis on HLA-B27. These families were composed of 32 cases and a total of 8 AS cases were discovered. In M and S families, 6 males and a female with AS were of HLA-B27. In K family, the proband with AS had no HLA-B27 and the other members were normal without HLA-B27. Some results of this genetic study of these families were as follows. HLA-B27 might be relevant to AS but the genes controlling AS were not limited to HLA-B27 only. Other factors-HLA-D locus, some infections and control factors for females-might trigger the disease. The disease was deemed to be of multigenic nature. There has been no report concerning genetic investigations for AH. This is to report the influence of hereditary factors for AH on 17 probands and 42 relatives of 16 AH families. In the AH families ossification of the yellow ligament (OYL), ossification of the posterior longitudinal ligament (OPLL) and ossification of the supra-spinous ligament (OSSL) were frequently observed roentgenographically in or around the spine, compared with the control group. There were 32 cases with OYL, 8 with OPLL and 29 with OSSL among 59 cases. Especially OYL and OSSL were frequently seen even in those under the age of 30 yr. There were 6 families in which the sibships of probands were able to be examined. Of 15 cases of these 6 families, 11 were involved with AH. More than 1/2 of the sibships were affected by AH. Of 15, 14 had some ossifications of the spinal ligament. Hahn's grooves of the vertebral bodies were observed in 44 of 59 members. Hahn's groove is already reported to be a causative factor of AH and is rarely encountered in normal persons after 20 yr of age. There may exist a genetic diathesis of ossification of the spinal ligaments and a heredity of AH.