Failure to support a pseudoautosomal locus for schizophrenia

Finger patterns and age of onset for the determination of the parent-of-origin in the transmission of schizophrenia

SUMMARY

Dermatoglyphic traits which are reported to be largely determined by genes could be considered as phenotypic characterestics and if the same are expressed through generations in schizophrenic families it can be speculated to serve as genetic markers for schizophrenia. Another factor that might be influenced by genes is the age of onset of the illness in the offspring and the parent of origin.

OBJECTIVE

This study was aimed to elucidate the occurrence of identical finger patterns in the schizophrenic patients and their affected parents. The other objective was to assess the age of onset of the illness in them.

METHODS

Forty six schizophrenic patients in whom one of the parents was also affected with schizophrenia or related disorders were recruited. Of these pairs 29 were taken up for finger patterns analysis, with an equal number of control group pairs. 35 proband and parent pairs were investigated for the age of onset of the illness.

RESULTS

The frequency of occurrence of identical patterns in the right thumbs of proband and their affected mother pairs was significantly more than between the proband and their affected father pairs. Additionally, the number of identical patterns was also more in the right thumbs of proband and their affected mother pairs compared with the control group. The difference between the mean age of onset of the illness in the probands and their affected fathers was more than between the probands and their affected mothers.

CONCLUSION

The genetic association of schizophrenic patients with the affected maternal side appear to be more stronger than with the paternal side.

Mode of transmission of schizophrenia

OBJECTIVE

Although the evidences for the phenomenon of "anticipation" and parental "imprinting" have been shown in schizophrenia, they are inconclusive. The purpose of this study was to test these hypotheses by examining three successive generations.

METHOD

58 schizophrenic patients who had their maternal or paternal parent or grandparent, or both, affected with schizophrenia or related disorders were analyzed. Chi-square test was used to assess the association of the sex of the parent with more than one of the affected proband families. The differences in the age of onset of the illness between the successive three generations was calculated using the t-test.

RESULTS

In comparison to mothers' affected families, a large proportion of the father side affected families had more than one of their offspring affected with the illness. The age of onset in probands was lower in comparison to that of those on the parental side and the difference was more significant when the paternal side was affected. Interestingly, when the age of onset in the grandparents was compared with either of the parental sides of the probands no difference emerged, indicating lack of support from this study for the theory of anticipation. At any rate, the age of onset of probands was significantly lower in comparison to that of the paternal grandfather side. Further, skipping of a generation in the process of transmission was noted in some families.

CONCLUSIONS

It is hard to ignore our findings that suggest paternal side transmission.