[Distribution of the frequency of various Mendelian modes of inheritance in families with retinopathia pigmentosa. Results of an evaluation of the RP register of the Munster University Ophthalmology Clinic].

International studies on the relative distribution of various genetic types of retinitis pigmentosa (RP) have revealed major regional differences, especially for x-recessive (1-24%) and autosomal dominant inheritance (3-39%). At present there are no data available concerning the population genetics of RP in Germany. We performed a study on the clinical findings and genetic classification of patients with tapetoretinal dystrophies based on a population of 702 German patients examined in our hospital between 1977 and 1990. Data were eligible on 603 of these patients for the standardized final study protocol. 78% (n = 473/603) of the study group patients were classified as typical non-syndrome RP cases. Second was Usher's syndrome (9.5% of all patients) and third choroideremia (2.3% of all patients). In 250 of the enrolled families with RP the reconstruction of pedigrees was sufficiently complete for a definite genetic characterization. The relative incidence of families with the different patterns of inheritance was: (1) single cases: 48.4%; (2) autosomal dominant: 25.2%; (3) autosomal recessive: 16.4%; (4) x-linked recessive: 10.0%.