{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,9,24]],"date-time":"2026-09-24T00:28:47Z","timestamp":1790209727037,"version":"4.1.0"},"reference-count":9,"publisher":"BMJ","issue":"2","content-domain":{"domain":[],"crossmark-restriction":false},"short-container-title":["J Med Genet"],"published-print":{"date-parts":[[1979,4]]},"abstract":"<jats:p>An attempt was made to ascertain all the dwarfs in the State of Victoria. The incidence of achondroplasia proved to be approximately 1 in 26,000 live births in the period 1969 to 1975 when ascertainment was nearly complete. This indicates a mutation rate of 1.93 X 10(-5) per generation in this locus. Paternal age was shown to influence mutation. Ascertainment in earlier years of the study was low despite the very great effort made to find all cases. Patients with hypochondroplasia were particularly difficult to find. However, 25 cases were found for study. Overlap between hypochondroplasia and achondroplasia was found in all features except the facial appearance (which was the basis of definition). Achondroplasia was more severe in all regards, but some individuals with hypochondroplasia were very short and some had extreme degrees of spinal canal stenosis. The classical measurements used to describe the skull changes in acondroplasia failed to distinguish this condition from hypochondroplasia. More efficient indices were devised, but visual assessment of the size of the facial region compared to that of the cranial valult proved more reliable than any index. The clinical distinction based upon facial appearance remains the arbitrary basis of definition.<\/jats:p>","DOI":"10.1136\/jmg.16.2.140","type":"journal-article","created":{"date-parts":[[2008,11,10]],"date-time":"2008-11-10T14:50:51Z","timestamp":1226328651000},"page":"140-146","source":"Crossref","is-referenced-by-count":144,"title":["Achondroplasia and hypochondroplasia. Comments on frequency, mutation rate, and radiological features in skull and spine."],"prefix":"10.1136","volume":"16","author":[{"given":"F","family":"Oberklaid","sequence":"first","affiliation":[],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"D M","family":"Danks","sequence":"additional","affiliation":[],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"F","family":"Jensen","sequence":"additional","affiliation":[],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"L","family":"Stace","sequence":"additional","affiliation":[],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"S","family":"Rosshandler","sequence":"additional","affiliation":[],"role":[{"vocabulary":"crossref","role":"author"}]}],"member":"239","published-online":{"date-parts":[[1979,4,1]]},"reference":[{"key":"ref_1","article-title":"Separating the effects of parental ages and birth order on the risk of certain birth defects. Unpublished data","author":"Fisher, R.J.; Sheffield, L.J.","year":"1978","unstructured":"Fisher, R. J., and Sheffield, L. J. (1978). Separating the effects of parental ages and birth order on the risk of certain birth defects. Unpublished data."},{"key":"ref_2","doi-asserted-by":"crossref","first-page":"141","DOI":"10.2214\/ajr.97.1.141","article-title":"Normal interpediculate distances (minium and maximum) in children and adults","volume":"97","author":"Hinck, V.C.; Clark, W.M.; Hopkins, C.E.","year":"1966","unstructured":"Hinck, V. C., Clark, W. M., and Hopkins, C. E. (1966). Normal interpediculate distances (minium and maximum) in children and adults. 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Achondroplasia: clinical radiologic features with comment on genetic implications. Clinical Pediatrics, 7, 474-485.","journal-title":"Clinical Pediatrics"},{"key":"ref_5","doi-asserted-by":"crossref","first-page":"11","DOI":"10.1136\/jmg.10.1.11","article-title":"Observations suggesting allelism of the achondroplasia and hypochondroplasia genes","volume":"10","author":"McKusick, V.A.; Kelly, T.E.; Dorst, J.P.","year":"1973","unstructured":"McKusick, V. A., Kelly, T. E., and Dorst, J. P. (1973). Observations suggesting allelism of the achondroplasia and hypochondroplasia genes. Journal of Medical Genetics, 10, 11-16.","journal-title":"Journal of Medical Genetics"},{"key":"ref_6","article-title":"Chondrodystrophic Dwarfs in Denmark","author":"M0rch, E.T.","year":"1941","unstructured":"M0rch, E. T. (1941). Chondrodystrophic Dwarfs in Denmark. Ejnar Munksgaard, Copenhagen."},{"key":"ref_7","doi-asserted-by":"crossref","first-page":"305","DOI":"10.1177\/028418516700600401","article-title":"Errors in the diagnosis of achondroplasia","volume":"6","author":"Silverman, F.N.; Brunner, S.","year":"1967","unstructured":"Silverman, F. N., and Brunner, S. (1967). Errors in the diagnosis of achondroplasia. Acta Radiologica, 6, 305-321.","journal-title":"Acta Radiologica"},{"key":"ref_8","first-page":"454","article-title":"Standards from birth to maturity for height, weight, height velocity","volume":"41","author":"Tanner, J.M.; Whitehouse, R.H.; Takaishi, M.","year":"1966","unstructured":"Tanner, J. M., Whitehouse, R. H., and Takaishi, M. (1966). Standards from birth to maturity for height, weight, height velocity: British children, 1965. Archives of Disease in Childhood, 41, 454-471.","journal-title":"Archives of Disease in Childhood"},{"key":"ref_9","first-page":"95","volume":"122","author":"Walker, B.A.; Murdoch, J.L.; McKusick, V.A.; Langer, L.O.; Beals, R.K.","year":"1971","unstructured":"Walker, B. A., Murdoch, J. L., McKusick, V. A., Langer, L. O., and Beals, R. K. (1971). Hypochondroplasia. American Journal of Diseases of Children, 122, 95-104.","journal-title":"Hypochondroplasia. American Journal of Diseases of Children"}],"container-title":["Journal of Medical Genetics"],"original-title":[],"language":"en","link":[{"URL":"https:\/\/syndication.highwire.org\/content\/doi\/10.1136\/jmg.16.2.140","content-type":"unspecified","content-version":"vor","intended-application":"similarity-checking"}],"deposited":{"date-parts":[[2025,10,17]],"date-time":"2025-10-17T18:23:42Z","timestamp":1760725422000},"score":1,"resource":{"primary":{"URL":"https:\/\/jmg.bmj.com\/lookup\/doi\/10.1136\/jmg.16.2.140"}},"subtitle":[],"short-title":[],"issued":{"date-parts":[[1979,4]]},"references-count":9,"journal-issue":{"issue":"2","published-online":{"date-parts":[[1979,4,1]]},"published-print":{"date-parts":[[1979,4]]}},"alternative-id":["10.1136\/jmg.16.2.140"],"URL":"https:\/\/doi.org\/10.1136\/jmg.16.2.140","relation":{},"ISSN":["0022-2593","1468-6244"],"issn-type":[{"value":"0022-2593","type":"print"},{"value":"1468-6244","type":"electronic"}],"subject":[],"published":{"date-parts":[[1979,4]]}}}