76
|
Akula JD, Hansen RM, Martinez-Perez ME, Fulton AB. Rod photoreceptor function predicts blood vessel abnormality in retinopathy of prematurity. Invest Ophthalmol Vis Sci 2007; 48:4351-9. [PMID: 17724227 DOI: 10.1167/iovs.07-0204] [Citation(s) in RCA: 73] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022] Open
Abstract
PURPOSE To test the hypothesis that early rod dysfunction predicts the blood vessel abnormalities that are the clinical hallmark of retinopathy of prematurity (ROP). METHODS Two rat models of ROP, induced by exposure to alternating 50%/10% oxygen (50/10 model) from postnatal day (P) 0 to P14, or exposure to 75% oxygen (75 model) from P7 to P14, and controls reared in room air were studied. In a longitudinal design, electroretinographic (ERG) records and digital fundus images were obtained at P20 +/- 1, P30 +/- 1, and P60 +/- 1. Rod sensitivity was derived from the ERG a-wave. Integrated curvature for the arterioles was calculated using Retinal Image multi-Scale Analysis (RISA) software. RESULTS In both ROP models, rod sensitivity was low at P20. Sensitivity improved by P60 in the 50/10 model, but remained low in the 75 model. Integrated curvature was high at P20 in both ROP models, decreased nearly to normal by P30 in the 50/10 model, but remained high in the 75 model, even at P60. At P20, rod sensitivity correlated with integrated vessel curvature. Furthermore, low rod sensitivity at P20 predicted abnormal retinal vasculature--that is, high integrated curvature--at P30 and P60. In contrast, vessel curvature at P20 did not predict sensitivity at P30 or P60. CONCLUSIONS The rods may instigate the vascular abnormalities that are the clinical hallmark of ROP.
Collapse
|
77
|
Liu K, Akula JD, Hansen RM, Moskowitz A, Kleinman MS, Fulton AB. Development of the electroretinographic oscillatory potentials in normal and ROP rats. Invest Ophthalmol Vis Sci 2006; 47:5447-52. [PMID: 17122135 DOI: 10.1167/iovs.06-0702] [Citation(s) in RCA: 40] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022] Open
Abstract
PURPOSE To study the development of the electroretinographic (ERG) oscillatory potentials (OPs) in rats and to compare normal OPs with those in a rat model of retinopathy of prematurity (ROP). METHODS Following a longitudinal design, ERG responses to a greater than 5 log unit range of full-field stimuli were recorded in dark-adapted rats at postnatal day (P) 18, P31, P47, and P67. The ERG records were digitally filtered (60-235 Hz), and the trough-to-peak amplitudes and implicit times of OP2, OP3, OP4, and OP5 were measured. Additionally, rats with oxygen-induced retinopathy, a model of ROP, were studied at P31. RESULTS Generally, OP amplitude increased and implicit time decreased with increasing stimulus intensity. The shape of the stimulus-response functions changed with age. The amplitudes of OP2, OP3, and OP4 were largest at P31. OP5 was largest at P47. All OPs were significantly affected in ROP rats; OP5 was least affected by ROP. CONCLUSIONS A prolonged normal course of OP development, which featured waxing and waning of amplitudes, was observed and might have been consequent to maturation and then to final refinements of inner retinal circuitry. In ROP rats, marked attenuation of early OPs was consistent with persistent dysfunction of photoreceptors, and significant attenuation of the late OP5 was evidence of compromised function of inner retinal circuitry.
Collapse
|
78
|
Fulton AB, Brecelj J, Lorenz B, Moskowitz A, Thompson D, Westall CA. Pediatric clinical visual electrophysiology: a survey of actual practice. Doc Ophthalmol 2006; 113:193-204. [PMID: 17109158 DOI: 10.1007/s10633-006-9029-6] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/07/2006] [Indexed: 11/25/2022]
Abstract
PURPOSE Survey the actual clinical practice of pediatric visual electrophysiology. The electrophysiologists surveyed were members of the International Society for Clinical Electrophysiology of Vision (ISCEV). METHODS A self-administered questionnaire with 55 items about visual evoked potential (VEP) and electroretinogram (ERG) testing of pediatric patients was sent to ISCEV members. The survey queried personnel, facilities, referral patterns and conduct of tests. RESULTS Nearly all respondents (94%) had advanced scientific or clinical degrees or both, and most (96%) worked in academic or medical facilities. Of the 71 respondents, 68 tested patients 12 years or younger, and nearly all of those performed both VEPs and ERGs. However, fewer than a third did high volume (>10/month) testing of infants and young children (< or =6 years). Eye care professionals and neurologists made the majority (57%) of the referrals, with the most common reason for referral being suspected visual impairment. Conduct of a pediatric test session often required more than one practitioner. For both VEP and ERG, more than 70% of respondents required at least 30 min for each test. The majority indicated that they followed the ISCEV standards for stimuli and data acquisition. Almost all (94%) reported using the ISCEV recommended VEP electrode configuration. For ERG, most (88%) used ocular contact electrodes (including contact lens, thread, foil and HK loop), but 12% used skin electrodes exclusively and some (17%) used skin electrodes at times. CONCLUSIONS Pediatric ERG and VEP testing is a labor intensive endeavor of highly trained professionals. ISCEV technical standards are typically met or exceeded, indicating that high quality testing of infants and children is feasible. Revision of the ISCEV ERG standard is necessary to bring actual practice into accord with evidence-based recommendations for infant testing.
Collapse
|
79
|
Abstract
PURPOSE Study the scotopic and photopic oscillatory potentials (OPs) of the electroretinogram (ERG) in 10-week old infants. METHODS Term-born 10-week old infants (n = 15) and adults (n = 12) were tested. Full-field ERGs were recorded under scotopic and photopic conditions. The records were filtered (75-300 Hz) to demonstrate the oscillatory wavelets. The amplitudes and implicit times of the infants' OPs were compared to those in adults and also to amplitudes of the saturated photoreceptor responses. RESULTS In infants, the mean OP amplitudes are similar in scotopic and photopic conditions and do not vary significantly with OP number. Infants' OPs are significantly smaller than in adults, with scotopic OPs averaging 19% of that in adults and photopic OPs averaging 47%, whereas the amplitudes of the saturated photoreceptor responses are 43% and 66% of those in adults. Mean interpeak intervals are similar in infants and adults, indicating oscillatory behavior at a frequency of 155 Hz in scotopic conditions and 135 Hz in photopic conditions. CONCLUSIONS In young infants, the OPs are relatively immature compared to the photoreceptor responses, with the immaturity of the scotopic responses being more marked than that of the photopic responses.
Collapse
|
80
|
Liu K, Akula JD, Falk C, Hansen RM, Fulton AB. The retinal vasculature and function of the neural retina in a rat model of retinopathy of prematurity. Invest Ophthalmol Vis Sci 2006; 47:2639-47. [PMID: 16723481 DOI: 10.1167/iovs.06-0016] [Citation(s) in RCA: 65] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022] Open
Abstract
PURPOSE In a rat model of retinopathy of prematurity (ROP), the retinal vasculature and function of the neural retina were studied longitudinally. Vascular and neural parameters were evaluated for significant relationships. METHODS Retinopathy was induced by exposing newborn rats to alternating 50% and 10% oxygen until age 14 days. To evaluate the function of the neural retina, electroretinographic (ERG) responses to full-field stimuli were recorded from dark-adapted rats at ages 18 and 31 days. Sensitivity and saturated amplitude of photoreceptor and postreceptor activity were derived from ERG a- and b- waves. To evaluate the retinal vasculature, digital fundus photographs were obtained at the same ages, and the tortuosity indices of the arterioles (TIA) and venules (TIV) were calculated. ROP rats and room-air-raised control animals were compared. Vascular and response parameters were evaluated for significant relationships. RESULTS In ROP rats, TIA was high at 18 days and decreased in every rat to nearly normal levels by 31 days. TIV was less affected by ROP or age. Deficits in all receptor and post-receptor response parameters were present in 18-day-old ROP rats. Post-receptor sensitivity recovered completely by 31 days. Deficits in other response parameters persisted. No significant correlations between vascular and ERG parameters were found in 18-day-old ROP rats. CONCLUSIONS Noninvasive, longitudinal measures in this model of ROP showed significant abnormalities in both the retinal vasculature and function of the neural retina that were most marked at age 18 days. However, vascular and neural abnormalities did not correlate.
Collapse
|
81
|
Fulton AB, Hansen RM, Moskowitz A, Barnaby AM. Multifocal ERG in subjects with a history of retinopathy of prematurity. Doc Ophthalmol 2006; 111:7-13. [PMID: 16502302 DOI: 10.1007/s10633-005-2621-3] [Citation(s) in RCA: 49] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 08/19/2005] [Indexed: 02/03/2023]
Abstract
PURPOSE Investigate the function of the central retina in subjects with a history of retinopathy of prematurity (ROP). METHODS Multifocal electroretinogram (mfERG) responses to a scaled array of 103 hexagons were recorded in subjects, aged 11-23 years (N = 11), with a documented history of mild ROP. The amplitude and implicit time of the components (N(1), P(1), N(2)) of the first order kernel for six concentric rings were compared to those of control subjects (N = 9). RESULTS The amplitude of each component varied significantly with eccentricity in both ROP and control subjects and was significantly smaller in the ROP subjects. The discrepancy between ROP and control subjects was greatest for central rings (1-3) and smaller for peripheral rings (4-6). The slopes of the functions summarizing log response density as a function of log eccentricity (degrees visual angle) were significantly shallower in ROP subjects. The implicit time of each component was longer in ROP subjects at all eccentricities. CONCLUSIONS ROP associated alterations in neural retinal development may underlie the subtle macular dysfunction disclosed by the mfERG.
Collapse
|
82
|
Anselm IA, Anselm IM, Alkuraya FS, Salomons GS, Jakobs C, Fulton AB, Mazumdar M, Rivkin M, Frye R, Poussaint TY, Marsden D. X-linked creatine transporter defect: a report on two unrelated boys with a severe clinical phenotype. J Inherit Metab Dis 2006; 29:214-9. [PMID: 16601897 PMCID: PMC2393549 DOI: 10.1007/s10545-006-0123-4] [Citation(s) in RCA: 45] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 10/24/2022]
Abstract
We report two unrelated boys with the X-linked creatine transporter defect (CRTR) and clinical features more severe than those previously described with this disorder. These two boys presented at ages 12 and 30 months with severe mental retardation, absent speech development, hypotonia, myopathy and extra-pyramidal movement disorder. One boy has seizures and some dysmorphic features; he also has evidence of an oxidative phosphorylation defect. They both had classical absence of creatine peak on brain magnetic resonance spectroscopy (MRS). In one, however, this critical finding was overlooked in the initial interpretation and was discovered upon subsequent review of the MRS. Molecular studies showed large genomic deletions of a large part of the 3' end of the complete open reading frame of the SLC6A8 gene. This report emphasizes the importance of MRS in evaluating neurological symptoms, broadens the phenotypic spectrum of CRTR and adds knowledge about the pathogenesis of creatine depletion in the brain and retina.
Collapse
|
83
|
Gelman R, Martinez-Perez ME, Vanderveen DK, Moskowitz A, Fulton AB. Diagnosis of plus disease in retinopathy of prematurity using Retinal Image multiScale Analysis. Invest Ophthalmol Vis Sci 2006; 46:4734-8. [PMID: 16303973 PMCID: PMC1418825 DOI: 10.1167/iovs.05-0646] [Citation(s) in RCA: 114] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022] Open
Abstract
PURPOSE To evaluate a semiautomated image analysis software package, Retinal Image multiScale Analysis (RISA), for the diagnosis of plus disease in preterm infants with retinopathy of prematurity (ROP). METHODS Digital images of the posterior pole showing both disc and macula in preterm infants with ROP were analyzed with an enhanced version of RISA. Venules (N = 106) and arterioles (N = 44) were identified, and integrated curvature, diameter, and tortuosity of the vessels were calculated. After the RISA calculations were completed, the origins of the vessels were determined to be 32 eyes in 16 infants (12 eyes with plus disease, 20 with no plus disease, as diagnosed by ophthalmic examination). Vessels were sorted into two groups-plus disease and no plus disease-and each RISA parameter was compared using the Mann-Whitney test. For each parameter, sensitivity and specificity were plotted as a function of cutoff criterion, receiver operating characteristic (ROC) curves were constructed, and the areas under the curve (AUC) were calculated. RESULTS For both arterioles and venules, each of the three parameters was significantly larger for the plus disease group. For instance, the median estimated arteriolar and venular diameters were approximately 12 mum greater in plus disease. Sensitivity and specificity plots indicated good accuracy of each parameter for the diagnosis of plus disease. The AUC showed that curvature had the highest diagnostic accuracy (0.911 for arterioles, 0.824 for venules). CONCLUSIONS The strong performance of RISA parameters in this sample suggests that RISA may be useful for diagnosing plus disease in preterm infants with ROP.
Collapse
|
84
|
Abstract
PURPOSE To assess cone photoreceptor and cone-mediated postreceptoral retinal function in infants. METHODS ERG responses to a 1.8-log unit range of long-wavelength flashes on a white, rod-saturating background were recorded in 4-week-old (n = 22) and 10-week-old (n = 28) infants and control adults and children, 8 to 40 years of age (n = 13). A model of the activation of cone phototransduction was fit to the a-waves. Sensitivity (S(CONE)) and saturated-response amplitude (R(CONE)) were calculated. The amplitude and implicit time of the b-wave were examined as a function of stimulus intensity. The cone photoresponse parameters were compared to the rod photoresponse parameters (S(ROD) and R(ROD)) in the same subjects. RESULTS S(CONE) and R(CONE) in infants were significantly smaller than in the mature control subjects. The mean S(CONE) was 64% and 68%, and the mean R(CONE) was 63% and 72% in 4- and 10-week-olds, respectively. The mean rod photoresponse parameters were considerably less mature, as the mean S(ROD) was 35% and 46%, and the mean R(ROD) was 39% and 43% of mature values at 4 and 10 weeks. The b-wave stimulus-response functions in the 4- and 10-week-old infants did not show the photopic hill that was characteristic of the children's and adults' photopic b-waves. CONCLUSIONS Peripheral cone function is relatively more mature than rod function in young infants. The lack of a photopic hill is hypothesized to result from immaturity in the relative contributions of ON and OFF bipolar cell responses.
Collapse
|
85
|
Lim M, Soul JS, Hansen RM, Mayer DL, Moskowitz A, Fulton AB. Development of Visual Acuity in Children With Cerebral Visual Impairment. ACTA ACUST UNITED AC 2005; 123:1215-20. [PMID: 16157801 DOI: 10.1001/archopht.123.9.1215] [Citation(s) in RCA: 41] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022]
Abstract
OBJECTIVE To study the development of visual acuity in term-born children with cerebral visual impairment and a history of neonatal hypoxic-ischemic encephalopathy. METHODS We studied 19 term-born children, aged 6 months to 6 years, with moderate to severe neonatal hypoxic-ischemic encephalopathy and behaviors indicative of cerebral visual impairment. Longitudinal measures of grating acuity were obtained using preferential looking (PL) and visual evoked potential (VEP) procedures. Visual acuities at first and last visits were compared. The courses of acuity development in the 9 children who underwent both VEP and PL acuity assessment at 4 or more ages were compared with normal development. RESULTS All children had measurable PL and VEP acuity, despite poor visual behavior. In nearly all, both PL and VEP acuity were below normal for age. For both PL and VEP measures, acuity at the last visit was, on average, 1 octave better than at the first visit, with a rate of improvement lower than normal. Although parallel courses of PL and VEP development occurred in many, substantial disparities in PL and VEP acuity were observed in others. CONCLUSIONS Modest increases in PL and VEP grating acuity occur during early childhood in many of these patients. The rate of increase is lower than normal.
Collapse
|
86
|
Tsina EK, Marsden DL, Hansen RM, Fulton AB. Maculopathy and retinal degeneration in cobalamin C methylmalonic aciduria and homocystinuria. ACTA ACUST UNITED AC 2005; 123:1143-6. [PMID: 16087854 DOI: 10.1001/archopht.123.8.1143] [Citation(s) in RCA: 49] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022]
|
87
|
Abstract
PURPOSE To study deactivation of the rod photoresponse in infants using a paired-flash procedure. Rhodopsin content increases and scales the parameters of the activation of rod phototransduction as rods develop. However, little is known about the kinetics of deactivation in the rods of young infants. METHODS ERG responses to pairs of flashes were used to study the recovery of the rod response in 4- and 10-week-old infants and mature control subjects. The amplitudes of rod isolated a-wave responses to a probe flash (+3.3 log scot td . s) presented 2 to 120 seconds after an equal-intensity test flash were measured. The interstimulus interval (ISI) at which the amplitude was half that of the response to the probe flash alone (t(50)) was determined by linear interpolation. RESULTS Recovery time (t(50)) was significantly longer in infants than in adults (F = 18.9, df 2, 32; P < 0.01). The shape of the recovery function did not vary with age. The t(50) values were inversely proportional to the parameters of activation of rod phototransduction. CONCLUSIONS These results are evidence that the kinetics of deactivation in infants are slower and may be set by the proportion of rhodopsin isomerized.
Collapse
|
88
|
Abstract
We tested the hypothesis that the kinetics of recovery of the rod photoresponse differ between mature and immature rods. A paired flash paradigm was used. The effect of a test flash on the ERG a-wave response to a probe flash presented 60 to 2 s after the test flash was studied. The functions summarizing the interaction between the test and probe flash did not differ significantly between infants and adults if the stimuli were equated for estimated proportion of rhodopsin isomerized/rod/flash. The kinetics of rod cell recovery are likely the same in infants and adults.
Collapse
|
89
|
Elias ER, Hansen RM, Irons M, Quinn NB, Fulton AB. Rod Photoreceptor Responses in Children With Smith-Lemli-Opitz Syndrome. ACTA ACUST UNITED AC 2003; 121:1738-43. [PMID: 14662594 DOI: 10.1001/archopht.121.12.1738] [Citation(s) in RCA: 32] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022]
Abstract
OBJECTIVE To test the hypothesis that the kinetics of activation and deactivation of rod phototransduction are altered in children with Smith-Lemli-Optiz syndrome (SLOS), a common genetic disorder caused by an inborn error in cholesterol biosynthesis. METHODS Thirteen patients with SLOS (median age, 4 years) were studied by means of scotopic full-field electroretinography. The kinetics of activation and deactivation of rod phototransduction were derived from the electroretinographic a-wave. Postreceptoral electroretinographic components were also evaluated. RESULTS The kinetics of activation were below normal limits in all but 3 of the 13 patients. Rod cell recovery (deactivation) in SLOS was slower than normal in all 8 patients in whom it was studied. Postreceptoral sensitivity was below normal limits in all but 1 of the 13 patients. CONCLUSIONS The kinetics of phototransduction are slow in children with SLOS. This is likely a consequence of altered sterol composition in the cell membranes of the rod photoreceptors. To our knowledge, this is the first demonstration of altered kinetics of a membrane-bound signaling system in SLOS. Investigation of other membrane-bound signaling systems may be warranted in the quest to understand development and phenotype of individuals with SLOS.
Collapse
|
90
|
Fulton AB, Hansen RM, Westall CA. Development of ERG responses: The ISCEV rod, maximal and cone responses in normal subjects. Doc Ophthalmol 2003; 107:235-41. [PMID: 14711155 DOI: 10.1023/b:doop.0000005332.88367.b8] [Citation(s) in RCA: 48] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
Abstract
PURPOSE Summarize ISCEV ERG responses from normal infants and children. METHODS The amplitudes and implicit times of the ISCEV rod, maximal dark-adapted and cone responses from a total of 409 normal infants (n = 128), children and adult controls were compiled. The subjects, aged 1 week to 52 years, were divided into seven age groups, including four in infancy (< 52 weeks). The response parameters for each age group were summarized as percentiles. RESULTS In each ISCEV condition, the youngest infants (1-5 weeks) had significantly smaller amplitudes and longer implicit times than adults. Amplitude increased and implicit time decreased systematically with age. CONCLUSIONS The developmental changes in ERG responses are significant. The medians and ranges herein provide provisional norms against which the ERG responses from pediatric patients can be compared.
Collapse
|
91
|
Cox GF, Hansen RM, Quinn N, Fulton AB. Retinal function in carriers of Bardet-Biedl syndrome. ARCHIVES OF OPHTHALMOLOGY (CHICAGO, ILL. : 1960) 2003; 121:804-10. [PMID: 12796250 DOI: 10.1001/archopht.121.6.804] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/14/2022]
Abstract
OBJECTIVE To test the hypothesis that carriers of Bardet-Biedl syndrome have abnormal rod-mediated responses. METHODS Parents (n = 26) of children with Bardet-Biedl syndrome (BBS), who are obligate carriers of BBS, consented to scotopic, full-field electroretinography (ERG). Responses were recorded over a 4 to 5 log unit range, up to a maximum stimulus of approximately +3.6 log scotopic troland seconds. The parameters of activation of the rod photoresponse, S (sensitivity parameter) and Rmp3(amplitude of the saturated rod response), were derived by fitting a transduction model to the ERG a-waves. For the b-wave, the stimulus producing a half maximum response (log sigma) and the saturated amplitude (Vmax) were determined. The model of the rod photoresponse was subtracted from the intact ERG to demonstrate a corneal positive potential (P2), and log kP2 and P2max were determined. The carriers' ERG responses were compared with those of healthy control subjects (n = 26). MAIN OUTCOME MEASURES Sensitivity (S, log sigma, and log kP2) and saturated amplitude (Rmp3, Vmax, and P2max) of receptoral and postreceptoral response components. RESULTS All parents had decreased P2 sensitivity, and most (15 [60%] of 26) had decreased b-wave sensitivity. The rod photoresponse sensitivity and the saturated amplitudes of the rod cell response, b-wave and P2, did not differ significantly between carriers and controls. CONCLUSIONS Diminished P2 sensitivity is characteristic of the carriers of BBS. The site of the primary defect in the BBS rod pathway appears to be proximal to the outer segments, most likely before the rod-bipolar cell synapse.
Collapse
|
92
|
Mykytyn K, Nishimura DY, Searby CC, Beck G, Bugge K, Haines HL, Cornier AS, Cox GF, Fulton AB, Carmi R, Iannaccone A, Jacobson SG, Weleber RG, Wright AF, Riise R, Hennekam RCM, Lüleci G, Berker-Karauzum S, Biesecker LG, Stone EM, Sheffield VC. Evaluation of complex inheritance involving the most common Bardet-Biedl syndrome locus (BBS1). Am J Hum Genet 2003; 72:429-37. [PMID: 12524598 PMCID: PMC379234 DOI: 10.1086/346172] [Citation(s) in RCA: 77] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/06/2002] [Accepted: 11/13/2002] [Indexed: 01/25/2023] Open
Abstract
Bardet-Biedl syndrome (BBS) is a genetic disorder with the primary features of obesity, pigmentary retinopathy, polydactyly, renal malformations, mental retardation, and hypogenitalism. Patients with BBS are also at increased risk for diabetes mellitus, hypertension, and congenital heart disease. BBS is known to map to at least six loci: 11q13 (BBS1), 16q21 (BBS2), 3p13-p12 (BBS3), 15q22.3-q23 (BBS4), 2q31 (BBS5), and 20p12 (BBS6). Although these loci were all mapped on the basis of an autosomal recessive mode of inheritance, it has recently been suggested-on the basis of mutation analysis of the identified BBS2, BBS4, and BBS6 genes-that BBS displays a complex mode of inheritance in which, in some families, three mutations at two loci are necessary to manifest the disease phenotype. We recently identified BBS1, the gene most commonly involved in Bardet-Biedl syndrome. The identification of this gene allows for further evaluation of complex inheritance. In the present study we evaluate the involvement of the BBS1 gene in a cohort of 129 probands with BBS and report 10 novel BBS1 mutations. We demonstrate that a common BBS1 missense mutation accounts for approximately 80% of all BBS1 mutations and is found on a similar genetic background across populations. We show that the BBS1 gene is highly conserved between mice and humans. Finally, we demonstrate that BBS1 is inherited in an autosomal recessive manner and is rarely, if ever, involved in complex inheritance.
Collapse
|
93
|
Mykytyn K, Nishimura DY, Searby CC, Shastri M, Yen HJ, Beck JS, Braun T, Streb LM, Cornier AS, Cox GF, Fulton AB, Carmi R, Lüleci G, Chandrasekharappa SC, Collins FS, Jacobson SG, Heckenlively JR, Weleber RG, Stone EM, Sheffield VC. Identification of the gene (BBS1) most commonly involved in Bardet-Biedl syndrome, a complex human obesity syndrome. Nat Genet 2002; 31:435-8. [PMID: 12118255 DOI: 10.1038/ng935] [Citation(s) in RCA: 234] [Impact Index Per Article: 10.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022]
Abstract
Bardet-Biedl syndrome (BBS, OMIM 209900) is a genetic disorder with the primary features of obesity, pigmentary retinopathy, polydactyly, renal malformations, mental retardation and hypogenitalism. Individuals with BBS are also at increased risk for diabetes mellitus, hypertension and congenital heart disease. What was once thought to be a homogeneous autosomal recessive disorder is now known to map to at least six loci: 11q13 (BBS1), 16q21 (BBS2), 3p13 p12 (BBS3), 15q22.3 q23 (BBS4), 2q31 (BBS5) and 20p12 (BBS6). There has been considerable interest in identifying the genes that underlie BBS, because some components of the phenotype are common. Cases of BBS mapping ro BBS6 are caused by mutations in MKKS; mutations in this gene also cause McKusick-Kaufman syndrome (hydrometrocolpos, post-axial polydactyly and congenital heart defects). In addition, we recently used positional cloning to identify the genes underlying BBS2 (ref. 16) and BBS4 (ref. 17). The BBS6 protein has similarity to a Thermoplasma acidophilum chaperonin, whereas BBS2 and BBS4 have no significant similarity to chaperonins. It has recently been suggested that three mutated alleles (two at one locus, and a third at a second locus) may be required for manifestation of BBS (triallelic inheritance). Here we report the identification of the gene BBS1 and show that a missense mutation of this gene is a frequent cause of BBS. In addition, we provide data showing that this common mutation is not involved in triallelic inheritance.
Collapse
|
94
|
Cooper LL, Hansen RM, Darras BT, Korson M, Dougherty FE, Shoffner JM, Fulton AB. Rod photoreceptor function in children with mitochondrial disorders. ARCHIVES OF OPHTHALMOLOGY (CHICAGO, ILL. : 1960) 2002; 120:1055-62. [PMID: 12149059 DOI: 10.1001/archopht.120.8.1055] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/14/2022]
Abstract
OBJECTIVE To test the hypothesis that function of the rod photoreceptors is abnormal in pediatric patients with mitochondrial disorders. METHODS Patients (n = 22; median age, 5 years) with a deficiency of 1 or more of the mitochondrial enzyme complexes, or a mutation in mitochondrial DNA, were studied by means of scotopic, full-field electroretinography (ERG). The conditions of ERG testing allowed derivation of the parameters of the activation of rod phototransduction from the ERG a-wave, and postreceptoral function from b-wave and P(2) stimulus-response functions. The deactivation of phototransduction was studied in 5 patients. The patients' ERG responses were compared with those of healthy control subjects (n = 25). RESULTS Responses from 19 patients were sufficient for analysis of rod photoreceptor and postreceptoral function. Saturated amplitudes of the rod photoresponse and b-wave sensitivity were significantly depressed in the patients. Saturated amplitudes of rod cell and P(2) responses were correlated. The kinetics of deactivation of phototransduction were slowed even if the kinetics of activation were normal. CONCLUSIONS In patients with mitochondrial disorders, some abnormalities of the scotopic ERG responses originate in the rod photoreceptors, but postreceptoral processes may also be abnormal. From a practical perspective, ERG testing can contribute to diagnosis of mitochondrial disorders.
Collapse
|
95
|
Bour LJ, Koo L, Delori FC, Apkarian P, Fulton AB. Fundus photography for measurement of macular pigment density distribution in children. Invest Ophthalmol Vis Sci 2002; 43:1450-5. [PMID: 11980860] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/24/2023] Open
Abstract
PURPOSE To evaluate a photographic procedure for reflectometry of the topographic distribution of macular pigment density in normal pediatric subjects. METHODS Digitized blue (480 nm) and green (540 nm) photographic images were aligned and subtracted to generate optical density difference maps. An 8 degrees x 8 degrees area concentric with the fovea was analyzed. Gaussian curves were fitted through the foveola along the vertical and horizontal meridians. The peak density and full widths at half maximum (FWHMs) were calculated. The subjects (n = 23; median age 10.5 years) had normal eyes and good acuity. RESULTS The peak macular pigment (MP) density was 0.13 +/- 0.04 density units (DU) which is at the lower end of the range previously obtained by other reflectometry procedures. Density distributions were circularly symmetrical. The FWHM ranged was 2.4 degrees +/- 0.5 degrees. Neither MP nor FWHM varied significantly with age. CONCLUSIONS The photographic method is feasible and provides quantitative assessment of topographic properties of macular pigment in young subjects. Future application to clinical studies of pediatric patients is envisioned.
Collapse
|
96
|
Jiang JC, Hansen RM, Reynaud X, Fulton AB. Background adaptation in a rat model of retinopathy of prematurity. Doc Ophthalmol 2002; 104:97-105. [PMID: 11949812 DOI: 10.1023/a:1014423514727] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
Abstract
Low dark-adapted, scotopic retinal and visual sensitivity in retinopathy of prematurity (ROP) could be due to disease of the inner retina, or the recently described rod photoreceptor abnormalities. Receptoral disease decreases catch of quanta from both test flashes and steady background lights; increment threshold functions are shifted up and right. In diseases with normal receptors but low retinal sensitivity due to abnormal post receptoral processing, the increment threshold functions are shifted up with no horizontal translation. Herein we test the hypothesis that the rod photoreceptors are the site of ROP disease which causes low dark adapted b-wave sensitivity. The effect of steady background light on the ERG b-wave in a rat model of ROP is studied. ERG stimulus/response functions were obtained using full-field stimuli in the dark-adapted state, and in the presence of a steady background light. In each adaptation condition, log sigma, the test flash intensity that produced a half-maximum b-wave amplitude, was calculated. In pilot experiments, the background light selected had raised log sigma about a log unit in controls. In dark-adapted ROP rats log sigma was significantly higher, 0.35 log unit, than in controls. In the presence of the background light, log sigma in ROP and control rats did not differ significantly indicating a relative shift, up and right, of the increment sensitivity function for the less sensitive ROP rats. The effect of the background light is consistent with receptoral disease causing low dark adapted b-wave sensitivity in ROP rats.
Collapse
|
97
|
Rivolta C, Peck NE, Fulton AB, Fishman GA, Berson EL, Dryja TP. Novel frameshift mutations in CRX associated with Leber congenital amaurosis. Hum Mutat 2001; 18:550-1. [PMID: 11748859 DOI: 10.1002/humu.1243] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
Abstract
Mutations in CRX, a photoreceptor-specific transcription factor, can cause Leber congenital amaurosis (LCA), cone-rod dystrophy (CORD), and retinitis pigmentosa (RP), all of which feature severe visual impairment. Upon screening 55 patients with Leber congenital amaurosis, 75 patients with cone-rod dystrophy, 13 with cone dystrophy, and 36 with recessive or isolate RP for changes in the CRX sequence, we found two patients with Leber congenital amaurosis who carried heterozygously one of two novel frameshift mutations. The first mutation, Tyr191(1-bp del), was a de novo change and the second change, Pro263(1-bp del) was inherited from the proband's affected father. Both mutations are predicted to encode mutant versions of CRX with altered carboxy termini. We also found a previously reported missense mutation, Arg41Gln, heterozygously in a 47-year-old patient with a form of RP. The missense change Val242Met was found in an isolate case of CORD and no controls; however, its pathogenicity remains uncertain because only limited segregation analysis was possible. A nonpathogenic missense change, Ala158Thr, was found to be a variant present at relatively high frequency among African-Americans.
Collapse
|
98
|
Mayer DL, Hansen RM, Moore BD, Kim S, Fulton AB. Cycloplegic refractions in healthy children aged 1 through 48 months. ARCHIVES OF OPHTHALMOLOGY (CHICAGO, ILL. : 1960) 2001; 119:1625-8. [PMID: 11709012 DOI: 10.1001/archopht.119.11.1625] [Citation(s) in RCA: 184] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/14/2022]
Abstract
OBJECTIVES To provide a description of refractive errors in healthy, term-born children, aged 1 through 48 months, and to test the hypotheses that spherical equivalent becomes significantly less hyperopic and less variable with increasing age. METHODS Following a prospective, cross-sectional design, cycloplegic retinoscopy was used to measure the refractive error in both eyes of 514 healthy, term-born children in 12 age groups. Three hundred were aged 12 months or younger. Spherical equivalent and cylindrical power and axis were analyzed as a function of age. Prediction limits for spherical equivalent were calculated. RESULTS Spherical equivalents of right and left eyes did not differ at any age. Hyperopia declined significantly with increasing age. The variability in spherical equivalent also decreased significantly with age. Cylindrical error of 1 diopter or more was found in 25% of the children; the proportion with astigmatism was highest in infancy and then waned. Myopia and anisometropia were rare, occurring in 3% and 1% of the sample, respectively. CONCLUSIONS Significant declines in hyperopia and variability of spherical equivalent appear to be features of emmetropization. The normal prediction limits provide guidelines against which data from individual patients can be compared.
Collapse
|
99
|
Fulton AB, Hansen RM, Petersen RA, Vanderveen DK. The rod photoreceptors in retinopathy of prematurity: an electroretinographic study. ARCHIVES OF OPHTHALMOLOGY (CHICAGO, ILL. : 1960) 2001; 119:499-505. [PMID: 11296015 DOI: 10.1001/archopht.119.4.499] [Citation(s) in RCA: 79] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/14/2022]
Abstract
OBJECTIVE To test the hypothesis that the more severe the acute phase retinopathy of prematurity (ROP) was in the preterm weeks, the more severely compromised is rod photoreceptor function after the ROP has resolved. METHODS Electroretinographic (ERG) responses were recorded from 25 dark-adapted children (ages 2.5 months' postterm to 14 years) categorized by maximum, acute phase ROP (None to Very Severe). From the ERG a-wave "S," a sensitivity parameter for the rod photoreceptor response, and R(mp3), the saturated amplitude of the rod photoreceptor response were calculated using a model of the activation of rod phototransduction. The patients' results were compared with those of healthy controls (n = 71). RESULTS Among those in the None, Mild, Moderate, and Severe categories, both S and R(mp3) varied significantly with severity of acute phase ROP. In the Very Severe category, ERG responses were too attenuated to calculate S and R(mp3). CONCLUSIONS The rod photoreceptors must be involved in ROP. The more severe the acute phase ROP, the more severe is the compromise of the processes involved in the activation of phototransduction in the rods.
Collapse
|
100
|
Nishimura DY, Searby CC, Carmi R, Elbedour K, Van Maldergem L, Fulton AB, Lam BL, Powell BR, Swiderski RE, Bugge KE, Haider NB, Kwitek-Black AE, Ying L, Duhl DM, Gorman SW, Heon E, Iannaccone A, Bonneau D, Biesecker LG, Jacobson SG, Stone EM, Sheffield VC. Positional cloning of a novel gene on chromosome 16q causing Bardet-Biedl syndrome (BBS2). Hum Mol Genet 2001; 10:865-74. [PMID: 11285252 DOI: 10.1093/hmg/10.8.865] [Citation(s) in RCA: 176] [Impact Index Per Article: 7.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
Abstract
Bardet-Biedl syndrome (BBS) is a genetically heterogeneous autosomal recessive disorder with the primary clinical features of obesity, pigmented retinopathy, polydactyly, hypogenitalism, mental retardation and renal anomalies. Associated features of the disorder include diabetes mellitus, hypertension and congenital heart disease. There are six known BBS loci, mapping to chromosomes 2, 3, 11, 15, 16 and 20. The BBS2 locus was initially mapped to an 18 cM interval on chromosome 16q21 with a large inbred Bedouin kindred. Further analysis of the Bedouin population allowed for the fine mapping of this locus to a 2 cM region distal to marker D16S408. Physical mapping and sequence analysis of this region resulted in the identification of a number of known genes and expressed sequence tag clusters. Mutation screening of a novel gene (BBS2) with a wide pattern of tissue expression revealed homozygous mutations in two inbred pedigrees, including the large Bedouin kindred used to initially identify the BBS2 locus. In addition, mutations were found in three of 18 unrelated BBS probands from small nuclear families.
Collapse
|