Living With Frontotemporal Degeneration: Diagnostic Journey, Symptom Experiences, and Disease Impact.

Frontotemporal degeneration (FTD) is an umbrella term encompassing a range of rare neurodegenerative disorders that cause progressive declines in cognition, behavior, and personality. Hearing directly from individuals living with FTD and their care partners is critical in optimizing care, identifying meaningful clinical trial endpoints, and improving research recruitment and retention. The current paper presents a subset of data from the FTD Insights Survey, chronicling the diagnostic journey, symptoms, and the impact of FTD on distress, quality of life, and independence, in the mild to moderate stages of the disease. Survey respondents included 219 individuals diagnosed with FTD and 437 current care partners, representing a range of FTD diagnoses. Around half of survey respondents reported seeing three or more doctors before an FTD diagnosis was given, and a range of prior diagnoses were noted. Most frequently endorsed symptoms tended to be consistent with clinical characteristics of the specific diagnosis, though there was significant variability in symptoms reported within diagnostic categories as well as considerable overlap in symptoms between diagnostic categories. Cognitive and language symptoms of FTD were generally most distressing to the person diagnosed, and a loss of independence was endorsed as affecting quality of life. The distinct perspectives of diagnosed persons and care partners regarding disease impact differed notably for bvFTD/Pick's disease. Participating independently in a range of activities, within the home, outside the home, and with other people, were reported as challenging for people living with FTD, underscoring the degree to which the lives of these individuals are affected even at the mild and moderate stages of disease. Overall, by heeding the perspectives of those living with FTD, we can begin to design more meaningful research studies, provide better care, and develop therapies that improve quality of life.

An early nonsense mutation facilitates the expression of a short isoform of CNGA3 by alternative translation initiation.

The cyclic nucleotide-gated (CNG) channel - composed of CNGA3 and CNGB3 subunits - mediates the influx of cations in cone photoreceptors after light stimulation and thus is a key element in cone phototransduction. Mutations in CNGA3 and CNGB3 are associated with achromatopsia, a rare autosomal recessive retinal disorder. Here, we demonstrate that the presence of an early nonsense mutation in CNGA3 induces the usage of a downstream alternative translation initiation site giving rise to a short CNGA3 isoform. The expression of this short isoform was verified by Western blot analysis and DAB staining of HEK293 cells and cone photoreceptor-like 661W cells expressing CNGA3-GST fusion constructs. Functionality of the short isoform was confirmed by a cellular calcium influx assay. Furthermore, patients carrying an early nonsense mutation were analyzed for residual cone photoreceptor function in order to identify a potential role of the short isoform to modify the clinical outcome in achromatopsia patients. Yet the results suggest that the short isoform is not able to compensate for the loss of the long isoform leaving the biological role of this variant unclear.

Molecular Findings in Families with an Initial Diagnose of Autosomal Dominant Retinitis Pigmentosa (adRP).

Genetic testing of probands in families with an initial diagnosis of autosomal dominant retinitis pigmentosa (adRP) usually confirms the diagnosis, but there are exceptions. We report results of genetic testing in a large cohort of adRP families with an emphasis on exceptional cases including X-linked RP with affected females; homozygous affected individuals in families with heterozygous, dominant disease; and independently segregating mutations in the same family. Genetic testing was conducted in more than 700 families with a provisional or probable diagnosis of adRP. Exceptions to the proposed mode of inheritance were extracted from our comprehensive patient and family database. In a subset of 300 well-characterized families with a probable diagnosis of adRP, 195 (70%) have dominant mutations in known adRP genes but 25 (8%) have X-linked mutations, 3 (1%) have multiple segregating mutations, and 3 (1%) have dominant-acting mutations in genes previously associated with recessive disease. It is currently possible to determine the underlying disease-causing gene and mutation in approximately 80% of families with an initial diagnosis of adRP, but 10% of "adRP" families have a variant mode of inheritance. Informed genetic diagnosis requires close collaboration between clinicians, genetic counselors, and laboratory scientists.

Single-base substitutions in the CHM promoter as a cause of choroideremia.

Although over 150 unique mutations affecting the coding sequence of CHM have been identified in patients with the X-linked chorioretinal disease choroideremia (CHM), no regulatory mutations have been reported, and indeed the promoter has not been defined. Here, we describe two independent families affected by CHM bearing a mutation outside the gene's coding region at position c.-98: C>A and C>T, which segregated with the disease. The male proband of family 1 was found to lack CHM mRNA and its gene product Rab escort protein 1, whereas whole-genome sequencing of an affected male in family 2 excluded the involvement of any other known retinal genes. Both mutations abrogated luciferase activity when inserted into a reporter construct, and by further employing the luciferase reporter system to assay sequences 5' to the gene, we identified the CHM promoter as the region encompassing nucleotides c.-119 to c.-76. These findings suggest that the CHM promoter region should be examined in patients with CHM who lack coding sequence mutations, and reveals, for the first time, features of the gene's regulation.

Next-generation sequencing to solve complex inherited retinal dystrophy: A case series of multiple genes contributing to disease in extended families.

PURPOSE: With recent availability of next-generation sequencing (NGS), it is becoming more common to pursue disease-targeted panel testing rather than traditional sequential gene-by-gene dideoxy sequencing. In this report, we describe using NGS to identify multiple disease-causing mutations that contribute concurrently or independently to retinal dystrophy in three relatively small families. METHODS: Family members underwent comprehensive visual function evaluations, and genetic counseling including a detailed family history. A preliminary genetic inheritance pattern was assigned and updated as additional family members were tested. Family 1 (FAM1) and Family 2 (FAM2) were clinically diagnosed with retinitis pigmentosa (RP) and had a suspected autosomal dominant pedigree with non-penetrance (n.p.). Family 3 (FAM3) consisted of a large family with a diagnosis of RP and an overall dominant pedigree, but the proband had phenotypically cone-rod dystrophy. Initial genetic analysis was performed on one family member with traditional Sanger single gene sequencing and/or panel-based testing, and ultimately, retinal gene-targeted NGS was required to identify the underlying cause of disease for individuals within the three families. Results obtained in these families necessitated further genetic and clinical testing of additional family members to determine the complex genetic and phenotypic etiology of each family. RESULTS: Genetic testing of FAM1 (n = 4 affected; 1 n.p.) identified a dominant mutation in RP1 (p.Arg677Ter) that was present for two of the four affected individuals but absent in the proband and the presumed non-penetrant individual. Retinal gene-targeted NGS in the fourth affected family member revealed compound heterozygous mutations in USH2A (p. Cys419Phe, p.Glu767Serfs*21). Genetic testing of FAM2 (n = 3 affected; 1 n.p.) identified three retinal dystrophy genes (PRPH2, PRPF8, and USH2A) with disease-causing mutations in varying combinations among the affected family members. Genetic testing of FAM3 (n = 7 affected) identified a mutation in PRPH2 (p.Pro216Leu) tracking with disease in six of the seven affected individuals. Additional retinal gene-targeted NGS testing determined that the proband also harbored a multiple exon deletion in the CRX gene likely accounting for her cone-rod phenotype; her son harbored only the mutation in CRX, not the familial mutation in PRPH2. CONCLUSIONS: Multiple genes contributing to the retinal dystrophy genotypes within a family were discovered using retinal gene-targeted NGS. Families with noted examples of phenotypic variation or apparent non-penetrant individuals may offer a clue to suspect complex inheritance. Furthermore, this finding underscores that caution should be taken when attributing a single gene disease-causing mutation (or inheritance pattern) to a family as a whole. Identification of a disease-causing mutation in a proband, even with a clear inheritance pattern in hand, may not be sufficient for targeted, known mutation analysis in other family members.

North Carolina macular dystrophy (MCDR1) caused by a novel tandem duplication of the PRDM13 gene.

PURPOSE: To identify the underlying cause of disease in a large family with North Carolina macular dystrophy (NCMD). METHODS: A large four-generation family (RFS355) with an autosomal dominant form of NCMD was ascertained. Family members underwent comprehensive visual function evaluations. Blood or saliva from six affected family members and three unaffected spouses was collected and DNA tested for linkage to the MCDR1 locus on chromosome 6q12. Three affected family members and two unaffected spouses underwent whole exome sequencing (WES) and subsequently, custom capture of the linkage region followed by next-generation sequencing (NGS). Standard PCR and dideoxy sequencing were used to further characterize the mutation. RESULTS: Of the 12 eyes examined in six affected individuals, all but two had Gass grade 3 macular degeneration features. Large central excavation of the retinal and choroid layers, referred to as a macular caldera, was seen in an age-independent manner in the grade 3 eyes. The calderas are unique to affected individuals with MCDR1. Genome-wide linkage mapping and haplotype analysis of markers from the chromosome 6q region were consistent with linkage to the MCDR1 locus. Whole exome sequencing and custom-capture NGS failed to reveal any rare coding variants segregating with the phenotype. Analysis of the custom-capture NGS sequencing data for copy number variants uncovered a tandem duplication of approximately 60 kb on chromosome 6q. This region contains two genes, CCNC and PRDM13. The duplication creates a partial copy of CCNC and a complete copy of PRDM13. The duplication was found in all affected members of the family and is not present in any unaffected members. The duplication was not seen in 200 ethnically matched normal chromosomes. CONCLUSIONS: The cause of disease in the original family with MCDR1 and several others has been recently reported to be dysregulation of the PRDM13 gene, caused by either single base substitutions in a DNase 1 hypersensitive site upstream of the CCNC and PRDM13 genes or a tandem duplication of the PRDM13 gene. The duplication found in the RFS355 family is distinct from the previously reported duplication and provides additional support that dysregulation of PRDM13, not CCNC, is the cause of NCMD mapped to the MCDR1 locus.

Identification of a Novel Gene on 10q22.1 Causing Autosomal Dominant Retinitis Pigmentosa (adRP).

Whole-genome linkage mapping identified a region on chromosome 10q21.3-q22.1 with a maximum LOD score of 3.0 at 0 % recombination in a six-generation family with autosomal dominant retinitis pigmentosa (adRP). All known adRP genes and X-linked RP genes were excluded in the family by a combination of methods. Whole-exome next-generation sequencing revealed a missense mutation in hexokinase 1, HK1 c.2539G > A, p.Glu847Lys, tracking with disease in all affected family members. One severely-affected male is homozygous for this region by linkage analysis and has two copies of the mutation. No other potential mutations were detected in the linkage region nor were any candidates identified elsewhere in the genome. Subsequent testing detected the same mutation in four additional, unrelated adRP families, for a total of five mutations in 404 probands tested (1.2 %). Of the five families, three are from the Acadian population in Louisiana, one is French Canadian and one is Sicilian. Haplotype analysis of the affected chromosome in each family and the homozygous individual revealed a rare, shared haplotype of 450 kb, suggesting an ancient founder mutation. HK1 is a widely-expressed gene, with multiple, abundant retinal transcripts, coding for hexokinase 1. Hexokinase catalyzes phosphorylation of glucose to glusose-6-phospate, the first step in glycolysis. The Glu847Lys mutation is in a highly-conserved site, outside of the active site or known functional sites.

Rates of decline in regions of the visual field defined by frequency-domain optical coherence tomography in patients with RPGR-mediated X-linked retinitis pigmentosa.

PURPOSE: To determine whether annual decline in visual field sensitivity is greater in the transition zone at the edge of the frequency-domain optical coherence tomography (fdOCT) inner segment ellipsoid zone (EZ) than at other locations in the visual field. DESIGN: Prospective, longitudinal, observational study. PARTICIPANTS: Forty-four patients with X-linked retinitis pigmentosa (XLRP) resulting from a mutation in the RPGR gene. METHODS: Static perimetric fields (Humphrey 30-2; Carl Zeiss Meditec, Dublin, CA) were obtained annually for 4 years. Beginning with year 2, fdOCT scans were obtained annually with a Heidelberg Spectralis HRA + OCT (Heidelberg Engineering, Heidelberg, Germany). MAIN OUTCOME MEASURES: The rate of visual field decline at locations near the edge of the EZ compared with the rates for the macula and in the mid periphery. RESULTS: Sensitivity just inside and outside the edge of the EZ declined at rates of 0.84 and 0.92 dB/year, respectively. By comparison, average sensitivity in the macula and mid periphery declined by 0.38 and 0.61 dB/year, respectively. CONCLUSIONS: The edge of the EZ in each patient with XLRP indicates a transition zone between relatively healthy and relatively degenerate retina. The annual loss of sensitivity in the transition zone is more rapid than it is elsewhere in the retina.

Next generation sequencing-based molecular diagnosis of retinitis pigmentosa: identification of a novel genotype-phenotype correlation and clinical refinements.

Retinitis pigmentosa (RP) is a devastating form of retinal degeneration, with significant social and professional consequences. Molecular genetic information is invaluable for an accurate clinical diagnosis of RP due to its high genetic and clinical heterogeneity. Using a gene capture panel that covers 163 of the currently known retinal disease genes, including 48 RP genes, we performed a comprehensive molecular screening in a collection of 123 RP unsettled probands from a wide variety of ethnic backgrounds, including 113 unrelated simplex and 10 autosomal recessive RP (arRP) cases. As a result, 61 mutations were identified in 45 probands, including 38 novel pathogenic alleles. Interestingly, we observed that phenotype and genotype were not in full agreement in 21 probands. Among them, eight probands were clinically reassessed, resulting in refinement of clinical diagnoses for six of these patients. Finally, recessive mutations in CLN3 were identified in five retinal degeneration patients, including four RP probands and one cone-rod dystrophy patient, suggesting that CLN3 is a novel non-syndromic retinal disease gene. Collectively, our results underscore that, due to the high molecular and clinical heterogeneity of RP, comprehensive screening of all retinal disease genes is effective in identifying novel pathogenic mutations and provides an opportunity to discover new genotype-phenotype correlations. Information gained from this genetic screening will directly aid in patient diagnosis, prognosis, and treatment, as well as allowing appropriate family planning and counseling.

Comprehensive molecular diagnosis of 179 Leber congenital amaurosis and juvenile retinitis pigmentosa patients by targeted next generation sequencing.

BACKGROUND: Leber congenital amaurosis (LCA) and juvenile retinitis pigmentosa (RP) are inherited retinal diseases that cause early onset severe visual impairment. An accurate molecular diagnosis can refine the clinical diagnosis and allow gene specific treatments. METHODS: We developed a capture panel that enriches the exonic DNA of 163 known retinal disease genes. Using this panel, we performed targeted next generation sequencing (NGS) for a large cohort of 179 unrelated and prescreened patients with the clinical diagnosis of LCA or juvenile RP. Systematic NGS data analysis, Sanger sequencing validation, and segregation analysis were utilised to identify the pathogenic mutations. Patients were revisited to examine the potential phenotypic ambiguity at the time of initial diagnosis. RESULTS: Pathogenic mutations for 72 patients (40%) were identified, including 45 novel mutations. Of these 72 patients, 58 carried mutations in known LCA or juvenile RP genes and exhibited corresponding phenotypes, while 14 carried mutations in retinal disease genes that were not consistent with their initial clinical diagnosis. We revisited patients in the latter case and found that homozygous mutations in PRPH2 can cause LCA/juvenile RP. Guided by the molecular diagnosis, we reclassified the clinical diagnosis in two patients. CONCLUSIONS: We have identified a novel gene and a large number of novel mutations that are associated with LCA/juvenile RP. Our results highlight the importance of molecular diagnosis as an integral part of clinical diagnosis.

Mutations in the small nuclear riboprotein 200 kDa gene (SNRNP200) cause 1.6% of autosomal dominant retinitis pigmentosa.

PURPOSE: The purpose of this project was to determine the spectrum and frequency of mutations in the small nuclear riboprotein 200 kDa gene (SNRNP200) that cause autosomal dominant retinitis pigmentosa (adRP). METHODS: A well-characterized adRP cohort of 251 families was tested for mutations in the exons and intron/exon junctions of SNRNP200 using fluorescent dideoxy sequencing. An additional 21 adRP families from the eyeGENE® Network were tested for possible mutations. Bioinformatic and segregation analysis was performed on novel variants. RESULTS: SNRNP200 mutations were identified in seven of the families tested. Two previously reported mutations, p.Arg681Cys and p.Ser1087Leu, were found in two families each. One family had the previously reported p.Arg681His mutation. Two novel SNRNP200 variants, p.Pro682Ser and p.Ala542Val, were also identified in one family each. Bioinformatic and segregation analyses suggested that these novel variants are likely to be pathogenic. Clinical examination of patients with SNRNP200 mutations showed a wide range of clinical symptoms and severity, including one instance of non-penetrance. CONCLUSIONS: Mutations in SNRNP200 caused 1.6% of disease in our adRP cohort. Pathogenic mutations were found primarily in exons 16 and 25, but the novel p.Ala542Val mutation in exon 13 suggests that variation in other genetic regions is also responsible for causing dominant disease. SNRNP200 mutations were associated with a wide range of clinical symptoms similar to those of individuals with other splice-factor gene mutations.

Mutations in a BTB-Kelch protein, KLHL7, cause autosomal-dominant retinitis pigmentosa.

Retinitis pigmentosa (RP) refers to a genetically heterogeneous group of progressive neurodegenerative diseases that result in dysfunction and/or death of rod and cone photoreceptors in the retina. So far, 18 genes have been identified for autosomal-dominant (ad) RP. Here, we describe an adRP locus (RP42) at chromosome 7p15 through linkage analysis in a six-generation Scandinavian family and identify a disease-causing mutation, c.449G-->A (p.S150N), in exon 6 of the KLHL7 gene. Mutation screening of KLHL7 in 502 retinopathy probands has revealed three different missense mutations in six independent families. KLHL7 is widely expressed, including expression in rod photoreceptors, and encodes a 75 kDa protein of the BTB-Kelch subfamily within the BTB superfamily. BTB-Kelch proteins have been implicated in ubiquitination through Cullin E3 ligases. Notably, all three putative disease-causing KLHL7 mutations are within a conserved BACK domain; homology modeling suggests that mutant amino acid side chains can potentially fill the cleft between two helices, thereby affecting the ubiquitination complexes. Mutations in an identical region of another BTB-Kelch protein, gigaxonin, have previously been associated with giant axonal neuropathy. Our studies suggest an additional role of the ubiquitin-proteasome protein-degradation pathway in maintaining neuronal health and in disease.

X-Chromosome Inactivation Is a Biomarker of Clinical Severity in Female Carriers of RPGR-Associated X-Linked Retinitis Pigmentosa.

PURPOSE: X-linked retinitis pigmentosa can manifest in female carriers with widely variable severity, whereas others remain unaffected. The contribution of X-chromosome inactivation (XCI) to phenotypic variation has been postulated but not demonstrated. Furthermore, the impact of genotype and genetic modifiers has been demonstrated in affected males but has not been well established in female carriers. The purpose of this study was to describe the scope of clinical phenotype in female carriers with mutations in RPGR and quantify the contribution of genotype, genetic modifiers, and XCI to phenotypic severity. DESIGN: Cohort study. PARTICIPANTS: Seventy-seven female carriers with RPGR mutations from 41 pedigrees. METHODS: Coding single nucleotide polymorphisms were sequenced in candidate genetic modifier genes encoding known RPGR-interacting proteins. X-chromosome inactivation ratios were determined in genomic DNA isolated from blood (n = 42) and saliva (n = 20) using methylation status of X-linked polymorphic repeats. These genetic data were compared with disease severity based on quantitative clinical parameters. MAIN OUTCOME MEASURES: Visual acuity, Humphrey visual field (HVF) results, full-field electroretinography results, and dark adaptation. RESULTS: Most individuals at all ages were mildly affected or unaffected, whereas those who progressed to moderate or severe vision loss were older than 30 years. RPGR genotype was not associated with clinical severity. The D1264N variant in RPGRIP1L was associated with more severe disease. Skewed XCI toward inactivation of the normal RPGR allele was associated with more severe disease. The XCI ratio in both blood and saliva was a predictor of visual function as measured by HVF diameter, rod amplitude, flicker amplitude, and flicker implicit time. For carriers with extreme XCI skewing of 80:20 or more, 57% were affected severely compared with 8% for those with XCI of less than 80:20 (P = 0.002). CONCLUSIONS: Female carriers with mutations in RPGR demonstrate widely variable clinical severity. X-chromosome inactivation ratios correlate with clinical severity and may serve as a predictor of clinically significant disease. Because RPGR gene therapy trials are underway, a future imperative exists to determine which carriers require intervention and when to intervene. X-chromosome inactivation analysis may be useful for identifying candidates for early intervention.

Mutations in the TOPORS gene cause 1% of autosomal dominant retinitis pigmentosa.

PURPOSE: The purpose of this project was to determine if mutations, including large insertions or deletions, in the recently identified RP31 gene topoisomerase I-binding arginine-serine rich (RS) protein (TOPORS), cause an appreciable fraction of autosomal dominant retinitis pigmentosa (adRP). METHODS: An adRP cohort of 215 families was used to determine the frequency of TOPORS mutations. We looked for mutations in TOPORS by testing 89 probands from the cohort without mutations in other known adRP genes. Mutation detection was performed by fluorescent capillary sequencing and by multiplex ligation probe amplification. RESULTS: Two different TOPORS mutations, p.Glu808X and p.Arg857GlyfsX9, were each identified in one proband. Patients with these mutations exhibited clinical signs typical of advanced adRP. No large deletions or insertions of TOPORS were identified in our study. CONCLUSIONS: Point mutations and small insertions or deletions in TOPORS cause approximately 1% of adRP. Large deletions or insertions of TOPORS are not an appreciable cause of adRP. Contrary to previous reports, no distinct clinical phenotype was seen in these patients.

Effect of Oral Valproic Acid vs Placebo for Vision Loss in Patients With Autosomal Dominant Retinitis Pigmentosa: A Randomized Phase 2 Multicenter Placebo-Controlled Clinical Trial.

Importance: There are no approved drug treatments for autosomal dominant retinitis pigmentosa, a relentlessly progressive cause of adult and childhood blindness. Objectives: To evaluate the potential efficacy and assess the safety of orally administered valproic acid (VPA) in the treatment of autosomal dominant retinitis pigmentosa. Design, Setting, and Participants: Multicenter, phase 2, prospective, interventional, placebo-controlled, double-masked randomized clinical trial. The study took place in 6 US academic retinal degeneration centers. Individuals with genetically characterized autosomal dominant retinitis pigmentosa were randomly assigned to receive treatment or placebo for 12 months. Analyses were intention-to-treat. Interventions: Oral VPA 500 mg to 1000 mg daily for 12 months or placebo. Main Outcomes and Measures: The primary outcome measure was determined prior to study initiation as the change in visual field area (assessed by the III4e isopter, semiautomated kinetic perimetry) between baseline and month 12. Results: The mean (SD) age of the 90 participants was 50.4 (11.6) years. Forty-four (48.9%) were women, 87 (96.7%) were white, and 79 (87.8%) were non-Hispanic. Seventy-nine participants (87.8%) completed the study (42 [95.5%] received placebo and 37 [80.4%] received VPA). Forty-two (46.7%) had a rhodopsin mutation. Most adverse events were mild, although 7 serious adverse events unrelated to VPA were reported. The difference between the VPA and placebo arms for mean change in the primary outcome was -150.43 degree2 (95% CI, -290.5 to -10.03; P = .035). Conclusions and Relevance: This negative value indicates that the VPA arm had worse outcomes than the placebo group. This study brings to light the key methodological considerations that should be applied to the rigorous evaluation of treatments for these conditions. This study does not provide support for the use of VPA in the treatment of autosomal dominant retinitis pigmentosa. Trial Registration: ClinicalTrials.gov Identifier: NCT01233609.

The Gly56Arg mutation in NR2E3 accounts for 1-2% of autosomal dominant retinitis pigmentosa.

PURPOSE: Mutations in the orphan nuclear receptor gene NR2E3 have been found to cause both recessive and dominant retinopathies. The purpose of this study was to determine the prevalence of the recently described Gly56Arg mutation in a well characterized cohort of families with autosomal dominant retinitis pigmentosa (adRP). METHODS: A cohort of 215 families with adRP which have already been screened for mutations in 13 of the other known adRP genes was used to determine the frequency of the Gly56Arg mutation. The 92 families without a disease-causing mutation in a known gene were tested for the presence of the Gly56Arg mutation using direct DNA sequencing. An additional set of 100 normal controls (200 chromosomes) was also screened by DNA sequencing. RESULTS: The Gly56Arg mutation was found in three of the 92 adRP families studied and was not found in unaffected control samples. CONCLUSIONS: The Gly56Arg mutation in NR2E3 accounts for approximately 1%-2% of adRP, making it one of the more common single mutations in adRP.

Visual acuity and cognitive outcomes at 4 years of age in a double-blind, randomized trial of long-chain polyunsaturated fatty acid-supplemented infant formula.

BACKGROUND: While there is a large body of data on the effects of long-chain polyunsaturated fatty acid supplementation of infant formula on visual and cognitive maturation during infancy, longterm visual and cognitive outcome data from randomized trials are scarce. AIM: To evaluate docosahexaenoic acid (DHA) and arachidonic acid (ARA)-supplementation of infant formula on visual and cognitive outcomes at 4 years of age. METHODS: Fifty-two of 79 healthy term infants who were enrolled in a single-center, double-blind, randomized clinical trial of DHA and ARA supplementation of infant formula were available for follow-up at 4 years of age. In addition, 32 breast-fed infants served as a "gold standard". Outcome measures were visual acuity and the Wechsler Preschool and Primary Scale of Intelligence--Revised. RESULTS: At 4 years, the control formula group had poorer visual acuity than the breast-fed group; the DHA- and DHA+ARA-supplemented groups did not differ significantly from the breast-fed group. The control formula and DHA-supplemented groups had Verbal IQ scores poorer than the breast-fed group. CONCLUSION: DHA and ARA-supplementation of infant formula supports visual acuity and IQ maturation similar to that of breast-fed infants.

A Novel Dominant Mutation in SAG, the Arrestin-1 Gene, Is a Common Cause of Retinitis Pigmentosa in Hispanic Families in the Southwestern United States.

Purpose: To identify the causes of autosomal dominant retinitis pigmentosa (adRP) in a cohort of families without mutations in known adRP genes and consequently to characterize a novel dominant-acting missense mutation in SAG. Methods: Patients underwent ophthalmologic testing and were screened for mutations using targeted-capture and whole-exome next-generation sequencing. Confirmation and additional screening were done by Sanger sequencing. Haplotypes segregating with the mutation were determined using short tandem repeat and single nucleotide variant polymorphisms. Genealogies were established by interviews of family members. Results: Eight families in a cohort of 300 adRP families, and four additional families, were found to have a novel heterozygous mutation in the SAG gene, c.440G>T; p.Cys147Phe. Patients exhibited symptoms of retinitis pigmentosa and none showed symptoms characteristic of Oguchi disease. All families are of Hispanic descent and most were ascertained in Texas or California. A single haplotype including the SAG mutation was identified in all families. The mutation dramatically alters a conserved amino acid, is extremely rare in global databases, and was not found in 4000+ exomes from Hispanic controls. Molecular modeling based on the crystal structure of bovine arrestin-1 predicts protein misfolding/instability. Conclusions: This is the first dominant-acting mutation identified in SAG, a founder mutation possibly originating in Mexico several centuries ago. The phenotype is clearly adRP and is distinct from the previously reported phenotypes of recessive null mutations, that is, Oguchi disease and recessive RP. The mutation accounts for 3% of the 300 families in the adRP Cohort and 36% of Hispanic families in this cohort.

Genomic rearrangements of the PRPF31 gene account for 2.5% of autosomal dominant retinitis pigmentosa.

PURPOSE: To determine whether genomic rearrangements in the PRPF31 (RP11) gene are a frequent cause of autosomal dominant retinitis pigmentosa (adRP) in a cohort of patients with adRP. METHODS: In a cohort of 200 families with adRP, disease-causing mutations have previously been identified in 107 families. To determine the cause of disease in the remaining families, linkage testing was performed with markers for 13 known adRP loci. In a large American family, evidence was found of linkage to the PRPF31 gene, although DNA sequencing revealed no mutations. SNP testing throughout the genomic region was used to determine whether any part of the gene was deleted. Aberrant segregation of a SNP near exon 1 was observed, leading to the testing of additional SNPs in the region. After identifying an insertion-deletion mutation, the remaining 92 families were screened for genomic rearrangements in PRPF31 with multiplex ligation-dependent probe amplification (MLPA). RESULTS: Five unique rearrangements were identified in the 93 families tested. In the large family used for linkage exclusion testing, an insertion-deletion was found that disrupts exon 1. The other four mutations identified in the cohort were deletions, ranging from 5 kb to greater than 45 kb. Two of the large deletions encompass all PRPF31 as well as several adjacent genes. The two smaller deletions involve either 5 or 10 completely deleted exons. CONCLUSIONS: In an earlier long-term study of 200 families with adRP, disease-causing mutations were identified in 53% of the families. Mutation-testing by sequencing missed large-scale genomic rearrangements such as insertions or deletions. MLPA was used to identify genomic rearrangements in PRPF31 in five families, suggesting a frequency of approximately 2.5%. Mutations in PRPF31 now account for 8% of this adRP cohort.