{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,3,29]],"date-time":"2026-03-29T11:44:35Z","timestamp":1774784675189,"version":"3.50.1"},"reference-count":55,"publisher":"Wiley","issue":"1-2","license":[{"start":{"date-parts":[[2005,6,3]],"date-time":"2005-06-03T00:00:00Z","timestamp":1117756800000},"content-version":"vor","delay-in-days":7093,"URL":"http:\/\/onlinelibrary.wiley.com\/termsAndConditions#vor"}],"content-domain":{"domain":[],"crossmark-restriction":false},"short-container-title":["Am. J. Med. Genet."],"published-print":{"date-parts":[[1986,1]]},"abstract":"<jats:title>Abstract<\/jats:title><jats:p>If the mother is the fragile X gene carrier, her daughters (and sons) with the mutation are at high risk of mental retardation. If the father is the (clinically unaffected) carrier, his daughters are normal. This is strong evidence for a maternal effect. The decreased penetrance and variable expressivity in fra(X) offspring of carriers could be related, at least in part, to variabile expression or availability of some meternal factor between pregnancies.<\/jats:p><jats:p>We hypothesize a maternal effect in fra(X), with variability in intelligence of heterozygotes and hemizygotes mediated mainly by the maternal uterus or placenta by virtue of different patterns of lyonization in those tissues between pregnancies. If the mother is a carrier, the matenal placenta could develop with a skewed proportion of the normal or the fra(X) genetically active. Each female or male embryo could be exposed to very different enviroments with respect to genetic activity fo the fra(X) chromosome, depending on the site of implantation within the uterus. If the father contributes the fra(X), the intrauterine enviroment is invariably normal and so are the daughters. Modifiers of the intrauterine effect could include lyonzation patterns in tissues of the carrier fetus, and preferential inactivation of the paternal X in extra\u2010embryonic tissues. The ultimate phenotype of the developing heterozygote and hemizygote may be determined by a threshold effect and interaction between the maternal genotype, the placental genotype, and the fetal genotype. The possibility of maternal effects is testable and has implications for treatment.<\/jats:p>","DOI":"10.1002\/ajmg.1320230163","type":"journal-article","created":{"date-parts":[[2005,6,11]],"date-time":"2005-06-11T20:02:23Z","timestamp":1118520143000},"page":"723-737","source":"Crossref","is-referenced-by-count":7,"title":["Maternal effect on intelligence in fragile X males and females"],"prefix":"10.1002","volume":"23","author":[{"given":"Daniel L.","family":"van Dyke","sequence":"first","affiliation":[],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Lester","family":"Weiss","sequence":"additional","affiliation":[],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"John M.","family":"Opitz","sequence":"additional","affiliation":[],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"James F.","family":"Reynolds","sequence":"additional","affiliation":[],"role":[{"role":"author","vocabulary":"crossref"}]}],"member":"311","published-online":{"date-parts":[[2005,6,3]]},"reference":[{"key":"e_1_2_1_2_1","doi-asserted-by":"publisher","DOI":"10.1159\/000131870"},{"key":"e_1_2_1_3_1","doi-asserted-by":"publisher","DOI":"10.1038\/306701a0"},{"key":"e_1_2_1_4_1","doi-asserted-by":"publisher","DOI":"10.1001\/archpedi.1982.03970410010002"},{"key":"e_1_2_1_5_1","doi-asserted-by":"publisher","DOI":"10.1007\/BF01848882"},{"key":"e_1_2_1_6_1","first-page":"577","article-title":"The cause of inverse symmetry","volume":"23","author":"Conklin EG","year":"1903","journal-title":"Anat Anz"},{"key":"e_1_2_1_7_1","doi-asserted-by":"publisher","DOI":"10.1007\/BF00274210"},{"key":"e_1_2_1_8_1","doi-asserted-by":"publisher","DOI":"10.1056\/NEJM198307213090304"},{"key":"e_1_2_1_9_1","doi-asserted-by":"publisher","DOI":"10.1002\/ajmg.1320140413"},{"key":"e_1_2_1_10_1","first-page":"218","article-title":"Bends in human mitotic metaphase chromosomes, including a bend marking the X\u2010inactivation center","volume":"36","author":"Flejter WL","year":"1984","journal-title":"Amer J Hum Genet"},{"key":"e_1_2_1_11_1","first-page":"33","volume-title":"Aspects of Human Genetics","author":"Fryns JP","year":"1984"},{"key":"e_1_2_1_12_1","doi-asserted-by":"publisher","DOI":"10.1007\/BF00291567"},{"key":"e_1_2_1_13_1","doi-asserted-by":"publisher","DOI":"10.1002\/ajmg.1320170417"},{"key":"e_1_2_1_14_1","first-page":"415","volume-title":"Cytogenetics of the Mammalian X Chromosome, Part B","author":"Glover TW","year":"1983"},{"key":"e_1_2_1_15_1","first-page":"125","article-title":"Possible maternal and hormonal factors in neurofibromatosis","volume":"29","author":"Hall JG","year":"1981","journal-title":"Arch Neurol"},{"key":"e_1_2_1_16_1","first-page":"200","volume-title":"Myotonic Dystrophy","author":"Harper PS","year":"1979"},{"key":"e_1_2_1_17_1","first-page":"96s","article-title":"Transmission of the fragile X syndrome through unaffected carrier males","volume":"36","author":"Howard\u2010Peebles PN","year":"1984","journal-title":"Am J Hum Genet"},{"key":"e_1_2_1_18_1","doi-asserted-by":"publisher","DOI":"10.1007\/BF00333538"},{"key":"e_1_2_1_19_1","doi-asserted-by":"publisher","DOI":"10.1002\/ajmg.1320070408"},{"key":"e_1_2_1_20_1","first-page":"640","article-title":"Fragile (X) X\u2010linked mental retardation. 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