Strengths and weaknesses in the cognitive profile of fra(X) patients.

In this paper we present data on the cognitive abilities analyzed by systematic, standardized psychometric testing in 18 fra(X) boys who participated in a multicenter, longitudinal study. In the majority of the patients no significant differences were found between verbal and performance intelligence. Higher performance IQ than verbal IQ was found primarily in higher functioning fra(X) males, indicating a possible effect of level of functioning on the direction of verbal-performance IQ differences. Subtest-analyses showed lowest performances in Number Concept and Arithmetic Skills, whereas better performances were reached in Object Assembly and Picture Completion. These data are discussed and compared with the results in previous studies reported up to now.

Adaptive behavior in the fra(X) syndrome: a longitudinal study in eight patients.

In this study we investigated the development of adaptive behavior of 8 fragile X [fra(X)] males with special attention to social competence and compared the results with a control group of 8 fra(X) negative males matched for age, level of adaptive functioning, and period of institutionalization.

A systematic cytogenetic study of a population of 1170 mentally retarded and/or behaviourly disturbed patients including fragile X-screening. The Hondsberg experience.

A cytogenetic study was performed in a population of 1170 mentally retarded and/or behaviourly disturbed patients of the Hondsberg Institute in the south of the Netherlands. The cytogenetic data are presented and discussed. In all patients chromosomal evaluation was performed with Giemsa-banding and Quinacrine fluorescence, and additional banding techniques were performed whenever they were necessary to clarify the chromosomal abnormality. A fragile X screening with M199 cultures was performed in 311 males. In 22.1% of the patients a chromosomal basis was found for their developmental retardation: 14.3% Down syndrome patients, 6.1% other chromosomal abnormalities (mainly partial autosomal trisomies and monosomies and sex-chromosome abnormalities). In 24 males, through 21 index patients, a positive fragile X screening was found, i.e. 6.7% of the screened population and 1.8% of the total population. These results indicate that the diagnostic contribution of the fragile X screening is numerically of equal importance as are advanced chromosome banding techniques, and its contribution to the diagnosis of fragile X syndrome in one index male patient in general leads to the detection of several female relatives at risk to be carrier of this X-linked recessively inherited condition. The causal relationship between the occurrence of mental retardation and chromosomal aberration in genera i.e. autosomal trisomies, partial autosomal trisomies and monosomies, and Xq27-28 fragility is well established and is, to some extent, easy to understand. Whether carriers of other chromosomal rearrangements, mainly of balanced reciprocal and Robertsonian translocations, small extra chromosomes, paracentric inversions and chromosomal variants, have increased risk for mental handicap and/or congenital malformations in their progeny, remains unclear at the present time. Some of these residual problems and questions are discussed in the perspective of their importance for genetic counseling. Detailed data will be presented about the mental development and psychological profile of patients with these different types of chromosomal abnormalities and rearrangements.