Prevalence of retinitis pigmentosa and allied disorders in Denmark. III. Hereditary pattern.

A national epidemiological study revealed 1301 prevalent cases of retinitis pigmentosa (RP) in the Danish population on January 1, 1988. The corresponding number of 974 families were analyzed with respect to Mendelian inheritance groups. Thirty families, comprising 6.9% of the prevalent RP-cases, were categorized with an autosomal dominant inheritance pattern. In 187 families, 22.6% of RP-cases, autosomal recessive heredity was encountered. X-linked heredity was found in 45 families, 10.8% of the RP-cases. Simplex RP-cases comprised 562 persons (43.2% of RP-cases). About a fourth of the non-systemic X-linked cases were females. Half of these had an age at onset after 30 years, but a third had their first RP-symptoms before age 18 years. A representative fraction of parents to non-systemic autosomal dominant, autosomal recessive, X-linked, and simplex cases were evaluated concerning their age at the time they had their first affected child. Mothers of the male simplex cases were of statistically significant higher age than mothers of the other inheritance groups. This may imply a high rate of new mutations among simplex cases, especially on the X-chromosome.     

Multicenter genetic study of retinitis pigmentosa in Japan: I. Genetic heterogeneity in typical retinitis pigmentosa

A nationwide, multicenter study of typical retinitis pigmentosa (RP) was carried out in collaboration with 18 hospitals throughout Japan to obtain current information for genetic counseling. We analyzed the genetic heterogeneity of RP based on the parental consanguinity of 434 probands registered during a 6-month period in 1990. A gradual decline in the frequency of consanguineous marriage was recognized among the normal parents of RP patients. The relative frequencies of inheritance patterns were estimated as: autosomal recessive, 25.2%; autosomal dominant, 16.9%; X-linked, 1.6%; and simplex, 56.3%. A comparison of these results with previous reports in Japan revealed a decline in the relative frequency of autosomal recessive cases and an increase in simplex cases. This suggests a decrease in the incidence of autosomal recessive retinitis pigmentosa in Japan, as well as the necessity for exhaustive investigations aimed at identifying inheritance patterns for RP patients seeking genetic counseling.     

A genetic analysis of retinitis pigmentosa.

Genetic analysis of 457 patients with retinitis pigmentosa (RP) included categorisation of families by recognised mendelian pattern of inheritance and formal segregation analysis of all informative sibships. Of the 368 probands a surprisingly high 18% (68) had significant congenital loss of hearing and were diagnosed as having Usher syndrome. The RP probands were categorised as: 21.7% autosomal dominant, 9.0% X-linked, 16.0% autosomal recessive, 3.3% genetic type uncertain, and 50.0% simplex. Segregation analysis reflected this high proportion of simplex cases, accounting for reduced penetrance in dominant families; only 20% remain classified as sporadic (possibly nongenetic). In the matings between normal persons estimates of the segregation ratio also indicate lower values than expected. Unlike in RP sibship, segregation in the Usher syndrome is consistent with the hypothesis of recessive inheritance. Therefore RP with significant hearing loss segregates as expected, while even if a proband is classified as a dominant or recessive the recurrence risk for the RP phenotype may be below mendelian expectation.     

Epidemiology of retinitis pigmentosa in Denmark

A nation-wide registration of Danish cases of retinitis pigmentosa (RP) provided 1890 persons diagnosed during the period 1850-1989. Prevalent at 1 January 1988 were 1301 persons (1:3943) comprising a multitude of different RP-types. Age specific prevalence rates demonstrated increasing rates of RP during the first four decades of life and a rather stable prevalence over the next 20-30 years. Corrected for incompleteness, a late decrease was found, reflecting an incomplete ascertainment of the oldest patients. A moving average method indicated an even later steady state value for the age-specific prevalence. The Danish prevalence figures were standardized according to the WHO World Standardized Prevalence Rates and compared with large studies from the USA and UK. No statistically significant difference was found. Usher syndrome was present in 12% of all RP-cases and Bardet-Biedl syndrome comprised 5%. Mental retardation was found in 144 cases (11%), mostly characterized by atypical RP. Nineteen per cent of patients affected by nonsystemic RP had an onset later than 30 years of age, whereas only a few per cent of persons with systemic RP had an RP onset after age 30 years. The Mendelian inheritance type of all cases was evaluated according to an unambiguous genetic classification, finding a larger amount of X-linked RP compared with other studies. Among nonsystemic RP-cases, 14.3% were found to be inherited as an X-linked trait whereas only 8.4% were autosomal dominantly inherited. The largest fraction was, as in previous materials, the simplex group (isolated cases) comprising 42.9% of the nonsystemic RP patients. Some factors influencing the results are discussed, with special emphasis on the problems associated with precise definitions of the Mendelian inheritance groups. A diagram according to the author's definition was constructed as a guideline ready for clinical application.     

视网膜色素变性发病机制及治疗进展

视网膜色素变性（retintis pigmentosa,RP）是指以进行性感光细胞及色素上皮功能丧失为共同表现的遗传性、退行性的疾病,RP是主要的致盲性眼病。其遗传方式包括X连锁遗传、常染色体隐性或者显性遗传,也有散发。临床表现为典型的三联征:骨细胞样色素沉着、视网膜血管缩窄和视盘蜡样苍白。RP具有高度的基因异质性(多个突变位点引起同一疾病）及表型异质性。本文对RP的发病机制和治疗方法进行简要综述。     

A survey of hereditary aspects of pigmentary retinal dystrophies

A study of 707 cases of retinitis pigmentosa and choroideraemia presenting over 12 years were classified according to their modes of inheritance-439 autosomal recessive (62%), 193 autosomal dominant (27%), 75 X-linked (10.7%). The patients with autosomal recessive transmission included 58 Usher syndrome, 12 Laurence-Moon-Bardet-Biedl syndrome and 33 Leber's congenital amaurosis. Another 37 had an early onset with macular degeneration and 31 were of late onset with pericentral dystrophy. Forty two were offspring of consanguineous parents. Of 193 individuals (78 families) with autosomal dominant inheritance, 20% had night blindness from early childhood. With X-linked transmission, 33 males and 31 female carriers comprised the retinitis pigmentosa group and eight males and three carrier females, choroideraemia. Almost all this X-linked group were of British ancestry. Of patients originating from the Mediterranean area, 94% had autosomal recessive disease.     

Genetic features of retinitis pigmentosa in Turkey

Sixty-two cases with retinitis pigmentosa from 42 index families were investigated to reveal the genetic features of the disease in Turkey. There were 42 propositi of whom 5 had a systemic syndrome associated with retinitis pigmentosa. Of the remaining 37 cases the condition was autosomal recessive in 21 (56.8%), sporadic in 12 (32.4%), autosomal dominant in 3 (8.1%) and X-linked recessive in one (2.7%). Sporadic cases may be more frequent as many hereditary cases are not brought to medical attention in rural families. Male preponderance among sporadic cases may indicate that there may be more X-linked cases. Nine out of 21 cases initially classified as sporadic displayed parental consanguinity and they were included as having autosomal recessive trait. Large families with autosomal recessive inheritance may prove valuable in linkage analysis and in defining future gene abnormalities.     

Congenital nystagmus--genetic and environmental causes.

A survey of 40 individuals registered with the Canadian National Institute for the Blind (CNIB) as blind from congenital nystagmus revealed that an abnormal single gene was responsible for the disorder in 33 patients. Fifteen of these were due to autosomal recessive conditions while X-linked disorders accounted for another 15 patients. In 3 cases the pedigrees were consistent with both autosomal recessive or X-linked inheritance. A clearly defined environmental origin was present in 1 case while specific genetic or environmental factors were not detected in the remaining six patients. The albinism, achromatopsia and Leber's congenital amaurosis groups of disorders were those most frequently detected.     

On the heredity of retinitis pigmentosa.

The aims of this study are: (1) to determine the frequencies of the various genetic forms of retinitis pigmentosa; and (2) to perform segregation analysis on autosomal dominant, autosomal recessive, and X-linked families. The families studied consisted of 2 series of patients at Moorfields Eye Hospital: (1) 426 families seen in the Genetic Clinic; and (2) 289 families seen in the Electrodiagnostic Department. Comparison between the 2 series identified biases of ascertainment, and it was estimated that the combined series included 53% of simplex cases and a minimum of 15% of X-linked families. Segregation analysis of the Genetic Clinic series showed good agreement with expectation in autosomal dominant and X-linked families, but indicated that no more than 70% of all simplex cases were autosomal recessive. The rest of the simplex cases were mildly affected and may represent fresh autosomal dominant mutations, autosomal dominant transmission with reduced penetrance, the heterozygous state of X-linked disease in some of the females, and phenocopies.     

Prevalence of posterior subcapsular lens opacities in patients with retinitis pigmentosa.

We clinically evaluated 338 patients with various genetic types of retinitis pigmentosa (RP) for the presence of posterior subscapsular (PSC) lens opacities. Of these, 180 (53%) had PSC lens changes or were bilaterally aphakic. Patients with X-linked recessive RP showed a greater prevalence and patients with autosomal dominant RP a lesser prevalence of PSC lens changes compared with autosomal recessive or isolated cases.     

Studies on retinitis pigmentosa in man. I. Taurine and blood platelets.

Platelets from patients with various genetically determined forms of photoreceptor dystrophy and with the clinical manifestations of retinitis pigmentosa (RP) have been studied. Variations in protein content have been observed, with less than normal in multiplex RP (probably autosomal recessive inheritance) and more in platelets from patients with autosomal dominant RP. This may reflect variation in platelet size or in surface adsorption of plasma proteins. Several patients presented with thrombocytopenia, the mean platelet count for X-linked hemizygote patients, as a group, being significantly lower than normal. Accumulation of 3H-taurine has been studied in platelets incubated in Ca2+-free Krebs bicarbonate medium containing 1.0 microM or 60.0 microM taurine, and in autologous plasma. Although, in general, platelets from patients with RP showed normal taurine uptake, the capacity of the higher affinity carrier was increased in patients with X-linked hemizygote and multiplex disease. In contrast, plasma from patients with X-linked hemizygote RP reduced the platelet tissue to medium ratio, established for 3H-taurine uptake, by 20%. More studies are needed to ascertain whether this represents a reduced taurine uptake or is caused by an increased concentration of taurine in the plasma.     

Multicenter genetic study of retinitis pigmentosa in Japan: II. Prevalence of autosomal recessive retinitis pigmentosa

Retinitis pigmentosa (RP) is a group of genetically heterogeneous diseases with autosomal recessive (AR), autosomal dominant, and X-linked modes of inheritance. Autosomal recessive retinitis pigmentosa (ARRP) is the most common form in Japan. A genetic analysis was done to determine the prevalence of ARRP indirectly, to provide an estimation of changing trends in the overall prevalence of RP. Data on the frequency of consanguinity and marriage year of normal parents of 59 ARRP patients were obtained from a nationwide multicenter survey of typical retinitis pigmentosa conducted in 1990. The gene frequency of ARRP was 0.01145 (Dahlberg's formula). In 1990, the number of young symptomatic ARRP patients decreased, while the number of patients aged 40 years and older increased. The total number of symptomatic ARRP patients in 1990 was nearly 21% higher than in 1970. Despite a dramatic decline in consanguinity in recent decades in Japan, the number of ARRP patients has increased. This increase is attributed to greater longevity and overall population growth. Our results suggest that the total number of RP patients has not decreased, and may even have increased.     

Prevalence of retinitis pigmentosa and allied disorders in Denmark. II. Systemic involvement and age at onset.

A population survey of retinitis pigmentosa and allied disorders in the Danish population disclosed 1301 cases prevalent in Denmark per January 1, 1988. Crude prevalence rates and World Standardized prevalences of systemic and non-systemic RP are presented. Sixty-four per cent of all RP-cases were non-systemic. A preponderance of males was encountered in both systemic and non-systemic RP. Usher disease was diagnosed in 12%, Bardet-Biedl syndrome constituted 5%, and the frequency of Spielmeyer-Vogt disease was 1% of all prevalent RP-cases. Other defined syndromes occurred in 1% of the cases. The Danish figures with respect to Usher disease are compared with standardized prevalence rates from Sweden and Finland. Nineteen per cent of patients affected by non-systemic RP had an onset later than 30 years of age. In patients affected by systemic RP the eye disease tended to an earlier debut with only a few per cent beginning after the age of 30 years.     

The empirical risk of retinitis pigmentosa in Japan]

The empirical risk of hereditary retinitis pigmentosa (RP), was studied based on a survey of the data from 378 families with RP who were seen in Juntendo University hospital from 1980 to 1988. If the cases have had affected sibling, the empirical risk is 19% for the other siblings, and 29% if they have parental consanguinity. Moreover the risk for male siblings is about 1.7 times higher than for female siblings. The prevalence in the general population of carriers with autosomal recessive hereditary RP was calculated to be about 0.8 to 1.7 in 100 persons. If a hereditary RP case marries a normal and unrelated partner, the risk is 0.4-0.9% for their child. If a case has many affected relatives (parents, grandparents, uncles or aunt etc), the risk is 24% for a son, and 30% for a daughter. Some normal persons among autosomal dominant families with incomplete penetrance are suspected to be carriers. The rate of penetration of the autosomal dominant gene was estimated to be 0.54. Therefore, the risk is 8.6% for the children of such persons. If the carriers are among X-linked families, the risk is 36% for their son. The risk is 1% or more for children of sporadic cases.     

Absence of ocular manifestations in autosomal dominant Alport syndrome associated with haematological abnormalties

Most patients with Alport syndrome have X-linked or autosomal recessive disease that is characterised by renal failure, hearing loss, and, in nearly 75% of the cases, a dot-and-fleck retinopathy and anterior lenticonus. There are only case reports of individuals with the rare autosomal dominant form, who can have haematuria or renal failure, deafness, and, in addition, low platelet counts and neutrophil inclusions. The ocular features of autosomal dominant inheritance have not been described. We have examined the eyes in the members of two families where Alport syndrome was diagnosed on the basis of the clinical features and family history, and where autosomal dominant inheritance was confirmed by father-to-son disease transmission, the associated haematological abnormalities, and haplotypes that segregated with the recently described locus at chromosome 22q. In Family A, the eyes of two individuals with haematuria, hearing loss, and haematological abnormalities and of nine unaffected family members were examined. In Family B, the eyes of two individuals with renal failure, normal hearing, and haematological abnormalities were examined. None of the affected or unaffected members in either family had a dot-and-fleck retinopathy, anterior lenticonus, a history suggesting recurrent corneal erosions, or corneal dystrophy. These results indicate that the protein abnormality in autosomal dominant Alport syndrome does not produce the retinopathy and lenticonus typical of X-linked and autosomal recessive disease. This may be because the abnormal protein is not present or is less important in the ocular basement membranes than elsewhere, or because the presence of a normal allele in autosomal dominant disease compensates for the defective allele.     

Absence of ocular manifestations in autosomal dominant Alport syndrome associated with haematological abnormalties

Most patients with Alport syndrome have X-linked or autosomal recessive disease that is characterised by renal failure, hearing loss, and, in nearly 75% of the cases, a dot-and-fleck retinopathy and anterior lenticonus. There are only case reports of individuals with the rare autosomal dominant form, who can have haematuria or renal failure, deafness, and, in addition, low platelet counts and neutrophil inclusions. The ocular features of autosomal dominant inheritance have not been described. We have examined the eyes in the members of two families where Alport syndrome was diagnosed on the basis of the clinical features and family history, and where autosomal dominant inheritance was confirmed by father-to-son disease transmission, the associated haematological abnormalities, and haplotypes that segregated with the recently described locus at chromosome 22q. In Family A, the eyes of two individuals with haematuria, hearing loss, and haematological abnormalities and of nine unaffected family members were examined. In Family B, the eyes of two individuals with renal failure, normal hearing, and haematological abnormalities were examined. None of the affected or unaffected members in either family had a dot-and-fleck retinopathy, anterior lenticonus, a history suggesting recurrent corneal erosions, or corneal dystrophy. These results indicate that the protein abnormality in autosomal dominant Alport syndrome does not produce the retinopathy and lenticonus typical of X-linked and autosomal recessive disease. This may be because the abnormal protein is not present or is less important in the ocular basement membranes than elsewhere, or because the presence of a normal allele in autosomal dominant disease compensates for the defective allele.     

A survey of hereditary aspects of pigmentary retinal dystrophies

A study of 707 cases of retinitis pigmentosa and choroideraemia presenting over 12 years were classified according to their modes of inheritance--439 autosomal recessive (62%), 193 autosomal dominant (27%), 75 X-linked (10.7%). The patients with autosomal recessive transmission included 58 Usher syndrome, 12 Laurence-Moon-Bardet-Biedl syndrome and 33 Leber's congenital amaurosis. Another 37 had an early onset with macular degeneration and 31 were of late onset with pericentral dystrophy. Forty two were offspring of consanguineous parents. Of 193 individuals (78 families) with autosomal dominant inheritance, 20% had night blindness from early childhood. With X-linked transmission, 33 males and 31 female carriers comprised the retinitis pigmentosa group and eight males and three carrier females, choroideraemia. Almost all this X-linked group were of British ancestry. Of patients originating from the Mediterranean area, 94% had autosomal recessive disease.     

结晶样视网膜色素变性临床与基础研究的机遇与挑战

结晶样视网膜色素变性（Bietti crystalline dystrophy,BCD）是视网膜色素变性中的一种特殊类型,其在东亚人群特别是中国人和日本人中较为常见。BCD的遗传方式为常染色体隐性遗传,唯一的致病基因为CYP4V2。对BCD患者自然史和CYP4V2突变导致BCD机制研究,将对确定BCD患者基因治疗的时间窗、临床研究中治疗效果评定以及探索治疗BCD其他方法均至关重要。（眼科,2020,29： 84-86）     

Genetische Untersuchungen bei kongenitaler Katarakt

Bilateral congenital cataract is genetic in at least 25% of cases. In contrast, unilateral congenital cataract is usually sporadic. Genetic heterogeneity is significant with the involvement of more than 30 genes having been identified to date. Phenotypes are defined by the location and morphology of the lens opacities. Mutations in the same gene may result in different phenotypes (clinical heterogeneity), and mutations in different genes may be associated with similar phenotypes (genetic heterogeneity). The mode of inheritance is mostly autosomal dominant but autosomal recessive and X-linked modes also occur. Expressivity may be variable and penetrance reduced. In X-linked cataract, carriers may show carrier signs. A precise pedigree analysis and a clinical examination of further family members are mandatory for correct genetic counselling. Metabolic cataract may be diagnosed biochemically. Molecular genetic analysis is not offered routinely to date with the exemption of a few genes.