The impact of genetic counselling on females in fragile X families

Attitude of medical school students in China towards genetic testing and counseling issues in FXS

Fragile X syndrome (FXS) is the most common form of inherited intellectual disability. However, genetic testing protocols and genetic counseling guidelines for FXS are not yet established in mainland China. In the present study, we conducted a comprehensive analysis using a self-administered questionnaire among students at the Xiangya medical school to investigate their attitude towards genetic testing and counseling issues of FXS. We have gained a general understanding of the attitudes of medical students towards these FXS issues in China. This information is of immense importance to develop appropriate genetic tests and to train counselors for FXS. As the medical school students surveyed are prospective physicians who will be a part of the Chinese health system, our survey was focused on the basic knowledge of FXS, population-based FXS screening, confidentiality and reproductive options for mutation carriers. The study demonstrated that only less than one third of the participants had heard about FXS. 94.6 % of participants were in favor of FXS screening for women in their reproductive age who had a genetic history of FXS. Furthermore, only half of the participants would inform their families about their genetic status in case of positive test results, and more than half of the participants supported natural conception and prenatal diagnosis for FXS mutation carriers. Additional findings and research implications are also discussed. This survey targeting potential doctors provides important information for the development of FXS genetic test and counselor training for the Chinese health system.

[Fragile X syndrome is still unrecognized: efficacy of molecular diagnosis in mentally retarded probands]

BACKGROUND

The fragile X mental retardation syndrome is the most common cause of inherited mental retardation. Identification of the unstable mutation responsible for the disease has allowed the design of a fully reliable molecular test for the diagnosis of the disease and for genetic counselling (identification of clinically normal carriers and prenatal diagnosis). We started in July 1991 to search for the mutation in mentally retarded probands, with no known cause for their phenotype. We present the results of a 42-month experience.

POPULATION AND METHODS

One thousand and one hundred fourty-nine probands were analysed. In case of a positive diagnosis, an extension of the molecular study to relatives was proposed. DNA samples were studied by Southern blot following EcoRI or EcoRI + EagI digestion. Clinical data were collected from referring clinicians.

RESULTS

Seventy-three carriers of a full mutation were identified, belonging to 52 families. The mean age of the fragile X probands was 16 +/- 14 years, which is very surprising for a disease that causes significant manifestations by the age of 2 to 3 years. This indicates an insufficient knowledge about this disease in France. Most of the demands for the test were from clinical geneticists. This diagnosis is of major importance for genetic counselling, as illustrated by the following study of 108 women at risk in these families.

CONCLUSIONS

The importance of an early diagnosis followed by an extended family study, for carrier screening and prevention of this severe disease, justifies molecular testing on any child with mental retardation or significant language delay of unknown cause, in the absence of clinical signs formally excluding a fragile X diagnosis.