Summary
It is well established that apparently unaffected males can be transmitters of the marker X syndrome trait. Cytogenetic and clinical investigations of these male transmitters are only rarely reported for most of these male transmitters are dead by the time the syndrome is diagnosed in their families. We report on cytogenetic and clinical investigations of two unaffected male carriers of the disorder from two large families. Pedigree analysis of these families revealed six other cases of possible male transmission of the marker X syndrome trait. Mental impairment was not reported from the siblings of these unaffected male carriers and could not be observed in their daughters. The mode of transmission of the disorder cannot be fully explained by X-linked inheritance. The phenomenon of unaffected males transmitting the disorder could be due to an autosomal suppressor systeme. Our findings indicate that male transmission may be important for the frequency of the disorder.
This is a preview of subscription content, log in via an institution to check access.
Similar content being viewed by others
References
Brøndum-Nielsen K, Tommerup N, Poulsen H, Mikkelsen M (1981) A pedigree showing transmission by apparently unaffected males and partial expression in female carriers. Hum Genet 59:23–25
Camerino G, Mattei MG, Mattei JF, Jaye M, Mandel JL (1983) Close linkage of fragile X mental retardation syndrome to hemophilia B and transmission through a normal male. Nature 306:701
Dunn HG, Renpenning H, Gerrard JW, Miller JR, Tabata T (1962) Mental retardation as a sex-linked defect. Am J Ment Defic 67:827–848
Fishburn J, Turner G, Daniel A, Brookwell R (1983) The diagnosis and frequency of X-linked conditions in a cohort of moderately retarded males with affected brothers. Am J Med Genet 14:713–724
Fonatsch C (1981) Chromosome banding in X-linked mental retardation. Lancet I:494
Froster-Iskenius U, Felsch G, Schirren C, Schwinger E (1983) Screening for fra(X)(q) in a population of mentally retarded males. Hum Genet 63:153–157
Fryns JP, van den Berghe H (1982) Transmission of fragile (X)(q27) from normal male(s). Hum Genet 61:262–263
Herbst DS, Miller JR (1980) Nonspecific X-linked mental retardation. II: The frequency in British Columbia. Am J Med Genet 7:461–469
Howell RT, McDermott A (1982) Replication status of the fragile X chromosome, fra(X)(q27), in three heterozygous females. Hum Genet 62:282–284
Hynie J (1969) Erfahrungen bei der Diagnostik und Therapie andrologischer Störungen. Andrologie 1:153–160
Jacobs PA, Mayer M, Matsuura J, Rhoads F, Yee SC (1983) A cytogenetic study of a population of mentally retarded males with special reference to the marker (X) syndrome. Hum Genet 63:139–148
Losowsky MS (1961) Hereditary mental defect showing the pattern of sex influence. J Ment Defic Res 5:60–62
Martin JP, Bell J (1943) A pedigree of mental defect showing sex linkage. J Neurol Neurosurg Psychol 6:154–157
Paul J, Froster-Iskenius U, Moje W, Schwinger E (1984) Heterozygous female carriers of the marker-X-chromosome: IQ estimation and replication status of fra(X)(q). Hum Genet 66:344–346
Prader A (1966) Die Hodengröße: Beurteilung und klinische Bedeutung. Triangle 7:240–243
Rhoads FA, Oglersby AC, Mayer M, Jacobs PA (1982) Marker X syndrome in an Oriental family with probable transmission by a normal male. Am J Med Genet 12:205–217
van Roy BC, de Smedt MC, Raes RA, Dumon JE, Leroy JG (1983) Fragile X trait in a large kindred: transmission also through normal males. J Med Genet 20:286–289
Sherman SL, Morton NE, Jacobs PA, Turner G (1984) The marker (X) syndrome: a cytogenetic and genetic analysis. Ann Hum Genet 48:21–37
Uchida IA, Freeman VCP, Jamro H, Partington MW, Soltau HC (1983) Additional evidence for fragile X activity in heterozygous carriers. Am J Hum Genet 35:861–868
Vogel F (to be published) Mutation and selection in the marker(X) syndrome. A Hypothesis. Ann Hum Genet
Webb GC, Rogers JG, Pitt DB, Halliday J, Theobald T (1981) Transmission of fragile (X)(q27) site from a male. Lancet II:1231–1232
Wolff G, Hameister H, Ropers HH (1978) X-linked mental retardation: transmission of the trait by an apparently unaffected male. Am J Med Genet 2:217–224
Author information
Authors and Affiliations
Rights and permissions
About this article
Cite this article
Froster-Iskenius, U., Schulze, A. & Schwinger, E. Transmission of the marker X syndrome trait by unaffected males: Conclusions from studies of large families. Hum Genet 67, 419–427 (1984). https://doi.org/10.1007/BF00291403
Received:
Revised:
Issue Date:
DOI: https://doi.org/10.1007/BF00291403