Family patterns of developmental dyslexia: Clinical findings

Abstract

Two separate groups of dyslexia families were ascertained through probands attending special schools for dyslexic students. An additional control group of families was ascertained through randomly selected students attending public schools. The 3 groups were interviewed by questionnaire about the family's demographic characteristics, and about the incidence of reading and spelling disorders in all first and second order relatives. One group of dyslexia families was also examined by standardized intelligence and academic achievement tests. Developmental dyslexia was found to aggregate in families; there were 4-5 times as many affected males as females among clinically identified students attending the special schools, but the sex ratio of affected relatives after probands had been excluded was approximately 1.4 males for every female. Sibs were at greater risk for reading difficulties when one parent was affected than when neither parent was affected. Sibs were also at greater risk for academic difficulties, and affected sibs were more severely impaired, when the father rather than the mother was the affected parent. In dyslexia families with 2 affected parents, the sibs were at greater risk, and the affected sibs were more severely impaired, than in families where only one parent was affected. Moreover, in families with 2 affected parents, both of the parents were more severely impaired in reading and spelling than parents of the same sex in families with one affected parent. Some indirect evidence is presented that assortative mating may codetermine patterns of affectedness in dyslexia families.

Family patterns of developmental dyslexia part III: Spelling errors as behavioral phenotype

“…The demographic and behavioral characteristics of families selected for study have been described in detail in earlier reports [Wolff and Melngailis, 1994;Wolff et al, 19951. Families were ascertained through probands attending specialized schools and a college for dyslexic students that only accepts students after an intensive review of previous school records, standardized intelligence tests, reading, writing, and spelling skills, focused language tests, and a physician's report [Wolff and Melngailis, 1994;Wolff et al, 19951.…”

A self-report questionnaire on reading-writing difficulties for adults. [Autoinforme de Trastornos Lectores para AdultoS (ATLAS)]

“…La idea subyacente es que los déficit lectores aparecen vinculados a la herencia genética y, por tanto, el riesgo de que un niño padezca dislexia es mayor cuando existen otros familiares afectados (Flax, Realpe-Bonilla, Roesler, Choudhury y Benasich, 2009;Shaywitz et al, 2008). Los resultados constatan que, comparados con sus controles, es más probable que niños con alto riesgo familiar desarrollen problemas para la adquisición de la lectura (Snowling, Gallagher y Frith, 2003;Wolff y Melengailis, 1994), alteraciones del desarrollo del lenguaje (Sptiz, Tallal, Flax y Benasich, 1997;Tallal, Ross y Curtiss, 1989), problemas de deletreo (Schulte-Körne, Deimel, Müller, Gutenbrunner y Remschmidt, 1996) o dificultades para discriminar la longitud fonémica (Pennala et al, 2010;Richardson et al, 2003). En suma, la mayor parte de los estudios han mostrado que el rendimiento alcanzado por los niños cuyos padres han informado de dificultades en la lectoescritura es más bajo que el de los controles (Decker, Vogler y DeFries, 1989;Gilger, 1992;Lefly y Pennington, 2000).…”

Self–reported reading problems in parents of twins with reading difficulties

“…[1][2][3][4][5][6][7][8] A l though the eti ol ogy of reading disability is almost certainly heterogeneous, 9 children with a family history of reading difficulties are at greater ri sk for devel opi ng readi ng probl ems than chi l dren w i th no fami l y hi story of readi ng di ffi cul ti es. 4,10 Thi s i ncreased rel ati ve ri sk for chi ldren w i th a posi ti ve fami l y hi story of readi ng probl ems may be suffi ci entl y hi gh to w arrant the use of such i nformati on i n a mul ti factori al assessment battery.…”