Neuropathy target esterase activity defines phenotypes among PNPLA6 disorders.

Biallelic pathogenic variants in the PNPLA6 gene cause a broad spectrum of disorders leading to gait disturbance, visual impairment, anterior hypopituitarism and hair anomalies. PNPLA6 encodes neuropathy target esterase (NTE), yet the role of NTE dysfunction on affected tissues in the large spectrum of associated disease remains unclear. We present a systematic evidence-based review of a novel cohort of 23 new patients along with 95 reported individuals with PNPLA6 variants that implicate missense variants as a driver of disease pathogenesis. Measuring esterase activity of 46 disease-associated and 20 common variants observed across PNPLA6-associated clinical diagnoses unambiguously reclassified 36 variants as pathogenic and 10 variants as likely pathogenic, establishing a robust functional assay for classifying PNPLA6 variants of unknown significance. Estimating the overall NTE activity of affected individuals revealed a striking inverse relationship between NTE activity and the presence of retinopathy and endocrinopathy. This phenomenon was recaptured in vivo in an allelic mouse series, where a similar NTE threshold for retinopathy exists. Thus, PNPLA6 disorders, previously considered allelic, are a continuous spectrum of pleiotropic phenotypes defined by an NTE genotype:activity:phenotype relationship. This relationship, and the generation of a preclinical animal model, pave the way for therapeutic trials, using NTE as a biomarker.

Genetic testing for inherited cardiovascular diseases. A position statement of the Polish Cardiac Society endorsed by Polish Society of Human Genetics and Cardiovascular Patient Communities.

According to the latest guidelines of European and American medical societies, genetic testing (GT) is essential in cardiovascular diseases for establishing diagnosis, predicting prognosis, enabling initiation of disease-modifying therapy, and preventing sudden cardiac death. The GT result may be relevant for cascade GT in the patient's relatives, for planning his/her profession and physical activity, and for procreative counseling. This position statement has been prepared due to the scarcity of GT in cardiovascular diseases in Poland and the need to expand its availability. We give a concise description of the genetic background of cardiomyopathies, channelopathies, aortopathies, familial hypercholesterolemia, pheochromocytomas, and paragangliomas. The article discusses various aspects of GT in specific populations, such as children or athletes, and also presents prenatal genetic diagnostics. We propose recommendations for GT and counselling, which take into account Polish needs and capabilities. We give an outline of legal regulations, good clinical practice in GT with respect for patient rights, the role of cardiologists and clinical geneticists in GT planning and post-test counseling, and the requirements for laboratories performing genetic tests. The Polish Cardiac Society and Polish Society of Human Genetics experts speak with one voice with cardiovascular patient communities to underline the need for a law on GT and increasing the availability of GT for cardiovascular patients.

Standard therapy or additionally radioactive iodine (131I) therapy; which will stop the recurrence of glioblastoma multiforme (GBM)?

Glioblastoma multiforme (GBM) is the most aggressive malignant brain tumour. The average survival time for a patient diagnosed with GBM, using standard treatment methods, is several months. Authors of the article pose a direct question: Is it possible to treat GBM solely with radioactive iodine (¹³¹I) therapy without employing the sodium iodide symporter (NIS) gene? After all, NIS has been detected not only in the thyroid but also in various tumours. The main author of this article (A.C.), with the assistance of her colleagues (physicians and pharmacologists), underwent ¹³¹I therapy after prior iodine inhibition, resulting in approximately 30% reduction in tumour size as revealed by magnetic resonance imaging (MRI). Classical therapy for GBM encompasses neurosurgery, conventional radiotherapy, and chemotherapy (e.g. temozolomide). Currently, tyrosine kinase inhibitors (imatinib, sunitinib, and sorafenib) are being used. Additionally, novel drugs such as crizotinib, entrectinib, or larotrectinib are being applied. Recently, personalised multimodal immunotherapy (IMI) based on anti-tumour vaccines derived from oncolytic viruses has been developed, concomitant with the advancement of cellular and molecular immunology. Thus, ¹³¹I therapy has been successfully employed for the first time in the case of GBM recurrence.

DNAJC30 Gene Variants Are a Frequent Cause of a Rare Disease: Leber Hereditary Optic Neuropathy in Polish Patients.

Leber hereditary optic neuropathy (LHON) is a rare disorder causing a sudden painless loss of visual acuity in one or both eyes, affecting young males in their second to third decade of life. The molecular background of the LHON is up to 90%, genetically defined by a point mutation in mitochondrial DNA. Recently, an autosomal recessive form of LHON (LHONAR1, arLHON) has been discovered, caused by biallelic variants in the DNAJC30 gene. This study provides the results of the DNAJC30 gene analysis in a large group of 46 Polish patients diagnosed with LHON, together with the clinical characterization of the disease. The c.152A>G (p.Tyr51Cys) substitution in the DNAJC30 gene was detected in all the patients as homozygote or compound heterozygote. Moreover, we identified one novel variant, c.293A>G, p.(Tyr98Cys), as well as two ultra-rare DNAJC30 variants: c.293A>C, p.(Tyr98Ser), identified to date only in one individual affected with LHONAR1, and c.130_131delTC (p.Ser44ValfsTer8), previously described only in two patients with Leigh syndrome. The patients presented here represent the largest group of subjects with DNAJC30 gene mutations described to date. Based on our data, the autosomal recessive form of LHON caused by DNAJC30 gene mutations is more frequent than the mitochondrial form in Polish patients. The results of our study suggest that Sanger sequencing of the single-exon DNAJC30 gene should be a method of choice applied to identify a molecular background of clinically confirmed LHON in Polish patients. This approach will help to reduce the costs of molecular testing.

Neuropathy target esterase activity predicts retinopathy among PNPLA6 disorders.

Biallelic pathogenic variants in the PNPLA6 gene cause a broad spectrum of disorders leading to gait disturbance, visual impairment, anterior hypopituitarism, and hair anomalies. PNPLA6 encodes Neuropathy target esterase (NTE), yet the role of NTE dysfunction on affected tissues in the large spectrum of associated disease remains unclear. We present a clinical meta-analysis of a novel cohort of 23 new patients along with 95 reported individuals with PNPLA6 variants that implicate missense variants as a driver of disease pathogenesis. Measuring esterase activity of 46 disease-associated and 20 common variants observed across PNPLA6 -associated clinical diagnoses unambiguously reclassified 10 variants as likely pathogenic and 36 variants as pathogenic, establishing a robust functional assay for classifying PNPLA6 variants of unknown significance. Estimating the overall NTE activity of affected individuals revealed a striking inverse relationship between NTE activity and the presence of retinopathy and endocrinopathy. This phenomenon was recaptured in vivo in an allelic mouse series, where a similar NTE threshold for retinopathy exists. Thus, PNPLA6 disorders, previously considered allelic, are a continuous spectrum of pleiotropic phenotypes defined by an NTE genotype:activity:phenotype relationship. This relationship and the generation of a preclinical animal model pave the way for therapeutic trials, using NTE as a biomarker.

Novel variants in the PAX6 gene related to isolated aniridia.

Aniridia, which is a rare congenital defect of the eye, consists of iris hypoplasia or aplasia, and additional ocular abnormalities. It is most commonly caused by autosomal dominant PAX6 gene mutations. However, in about 30% of cases, it is associated with chromosomal rearrangements in the 11p13 region. The aim of this study was to identify the potential PAX6 gene variants, which could cause the isolated aniridia. Eight patients with isolated aniridia were included in this study. MLPA analysis allowed in the past to exclude large structural rearrangements of the PAX6 and adjacent genes like WT1. Blood samples were collected from the patients (and their families in familial cases) and genomic DNA was extracted from peripheral blood leukocytes and buccal cells. The amplification of the 11 exons of the PAX6 gene was performed. Bidirectional Sanger Sequencing was conducted for the identification of the potentially pathogenic variants, and for the segregation analysis of the identified variant in the family. The results were analyzed with the use of CodonCode Aligner software. In three patients, aniridia was sporadic, whereas in another five cases, the eye defect was familial. The potentially pathogenic variants in the PAX6 gene were found in 6 out of 8 patients with aniridia. We identified four known (c.781C > T, c.607C > T, and c.949C > T twice), and two novel variants (c.258_265del and c.495_496insG). Point mutations in the PAX6 gene are the most frequent cause of aniridia. The investigation of the genetic background of the disease is essential for patients to evaluate recurrence risk in the offspring.

Molecular Re-Diagnosis with Whole-Exome Sequencing Increases the Diagnostic Yield in Patients with Non-Syndromic Retinitis Pigmentosa.

Retinitis pigmentosa (RP) is a clinically and genetically heterogeneous group of disorders with progressive loss of photoreceptor and pigment epithelial function. Nineteen unrelated Polish probands clinically diagnosed with nonsyndromic RP were recruited to this study. We used whole-exome sequencing (WES) to identify potential pathogenic gene variants in molecularly undiagnosed RP patients, as a molecular re-diagnosis after having performed targeted NGS in the past. Targeted NGS allowed for identification of the molecular background in only 5 out of 19 patients. Fourteen patients who remained unsolved despite the targeted NGS were subjected to WES. WES revealed potentially causative variants in RP-related genes in another 12 patients. Together, NGS methods revealed the coexistence of causal variants affecting distinct RP genes in 17 out of 19 RP families, with a very high efficiency of 89%. With the improvement of NGS methods, including higher sequencing depth, broader target enrichment, and better bioinformatic analysis capabilities, the ratio of identified causal gene variants has significantly increased. Therefore, it is important to consider repeating high-throughput sequencing analysis in those patients in whom the previously performed NGS did not reveal any pathogenic variants. The study confirmed the efficiency and clinical utility of re-diagnosis with WES in molecularly undiagnosed RP patients.

CDHR1-Related Cone-Rod Dystrophy: Clinical Characteristics, Imaging Findings, and Genetic Test Results-A Case Report.

Background: Cone-rod dystrophies (CRDs) are a heterogeneous group of inherited retinal diseases (IRDs) characterized by cone photoreceptor loss, that is followed by subsequent rod photoreceptor impairment. Case presentation: A 49-year-old man complaining of diminution of vision in both eyes (OU) was referred to our outpatient clinic. He reported visual loss for 5 years, but it was most progressive during the last few months. The best-corrected visual acuity (BCVA) at presentation was 0.4 in the right eye (RE) and 1.0 in the left eye (LE). Fundus fluorescein angiography (FFA) revealed granular hyperfluorescence in the macula and concomitant areas of capillary atrophy. Flash full-field electroretinography (ffERG) showed lowering of a and b waves as well as prolonged peak time in light-adapted conditions. However, outcomes of dark-adapted ERGs were within normal limits. Based on the constellation of clinical, angiographic, and electrophysiological tests findings, a diagnosis of IRD was suspected. Genetic testing showed a homozygous, pathogenic c.783G>A mutation in the cadherin-related family member 1 (CDHR1) gene, which confirmed CRD type 15 (CRD15). Conclusions: We demonstrate the clinical characteristics, retinal imaging outcomes, and genetic test results of a patient with CRD15. Our case contributes to expanding our knowledge of the clinical involvement of the pathogenic mutation c.783G>A in CDHR1 variants.

Molecular background of Leber congenital amaurosis in a Polish cohort of patients-novel variants discovered by NGS.

Leber congenital amaurosis (LCA) is the most severe form of inherited retinal dystrophies and the most frequent cause of congenital blindness in children. To date, 25 genes have been implicated in the pathogenesis of this rare disorder. Performing an accurate molecular diagnosis is crucial as gene therapy is becoming available. This study aimed to report the molecular basis of Leber congenital amaurosis, especially novel and rare variants in 27 Polish families with a clinical diagnosis of LCA fully confirmed by molecular analyses. Whole exome sequencing or targeted next-generation sequencing (NGS) of inherited retinal dystrophies-associated (IRD) genes was applied to identify potentially pathogenic variants. Bidirectional Sanger sequencing and quantitative PCR (qPCR) were carried out for validation and segregation analysis of the variants identified within the families. We identified 28 potentially pathogenic variants, including 11 novel, in 8 LCA genes: CEP290, CRB1, GUCY2D, NMNAT1, RPGRIP1, CRX, LRAT1, and LCA5. This study expands the mutational spectrum of the LCA genes. Moreover, these results, together with the conclusions from our previous studies, allow us to point to the most frequently mutated genes and variants in the Polish cohort of LCA patients.

Deterioration of visual quality and acuity as the first sign of ceroid lipofuscinosis type 3 (CLN3), a rare neurometabolic disease.

Ceroid lipofuscinosis type 3 (CLN3) is an autosomal recessive, neurodegenerative metabolic disease. Typical clinical symptoms include progressive visual loss, epilepsy of unknown etiology and dementia. Presence of lipofuscin deposits with typical pattern of 'fingerprints' and vacuolized lymphocytes suggest the diagnosis of CLN3. Cause of CLN3 are mutations in the CLN3 gene, among which the most frequently found is the large deletion 1.02 kb spreading on exons 7 and 8. We present 4 patients from 2 families, in whom the deterioration of visual quality and acuity was observed as first clinical sign, when they were a few years old and it was successively accompanied by symptoms of neurologic deterioration (like generalized convulsions with consciousness impairment). In all patients the 1.02 kb deletion in the CLN3 gene was detected in homo- or heterozygosity with other CLN3 pathogenic variant. Ultrastructural studies revealed abnormal structures corresponding to 'fingerprint' profiles (FPPs) in conjunctival endothelial cells. It should be emphasized that in patients with blindness of unknown cause the diagnosis of ceroid lipofuscinosis should be considered and in older children-especially CLN3. The facility of the analysis for the presence of 1.02 kb deletion and economic costs are a solid argument for intensive use of this test in the diagnostic procedure of CLN3.

Ciliary phenotyping in renal epithelial cells in a cranioectodermal dysplasia patient with WDR35 variants.

Background: Cranioectodermal dysplasia (CED) is a skeletal autosomal recessive ciliopathy. The characteristic clinical features of CED are facial dysmorphisms, short limbs, narrow thorax, brachydactyly, ectodermal abnormalities, and renal insufficiency. Thus far, variants in six genes are known to be associated with this disorder: WDR35, IFT122, IFT140, IFT144, IFT52, and IFT43. Objective: The goal of this study was to perform cilium phenotyping in human urine-derived renal epithelial cells (hURECs) from a CED patient diagnosed with second-stage chronic kidney disease (CKD) and three unrelated and unaffected pediatric controls. Methods: Genetic analysis by WDR35 screening was performed in the affected individual. Cilium frequency and morphology, including cilium length, height, and width, were evaluated by immunofluorescence (IF) experiments in hURECs using two markers visualizing the ciliary axoneme (Acet-Tub and ARL13B) and the base of the cilium (PCNT). The IF results were analyzed using a confocal microscope and IMARIS software. Results: WDR35 analysis revealed the presence of a known nonsense p. (Leu641*) variant and a novel missense variant p. (Ala1027Thr). Moreover, comparative genomic hybridization analysis showed that the patient carries a microdeletion on chromosome 7q31.1. Ciliary phenotyping performed on hURECs showed morphological differences in the patient's cilia as compared to the three controls. The cilia of the CED patient were significantly wider and longer. Conclusion: The obtained results suggest that CED-related second-stage CKD might be associated with cilia abnormalities, as identified in renal epithelial cells from a CED patient harboring variants in WDR35. This study points out the added value of hURECs in functional testing for ciliopathies.

Phenotypic Variation of Autosomal Recessive Leber Hereditary Optic Neuropathy (arLHON) in One Family.

Leber hereditary optic neuropathy (LHON) is a rare disease with a prevalence of 1 in 25,000 births. LHON usually presents in young males, with painless loss of visual acuity in one or both eyes. Recently an autosomal recessive form of the disease (arLHON or LHONAR) has been described, which is caused by a biallelic mutation in the DNAJC30 gene (usually a missense mutation c.152A>G). The phenotypic and clinical characteristics of patients with arLHON are similar to those of mtLHON, but some differences have been described. Therapy is problematic and challenging. This paper describes clinical and electrophysiological findings in one family (three children and two parents) with arLHON and emphasizes the role of Photopic Negative Response Electroretinography, which provides objective measurement of retinal ganglion cells function. In Leber hereditary optic neuropathy, abnormal retinal ganglion cells function can be found in both eyes, even if visual acuity loss only occurs in one eye. Early clinical diagnosis, confirmed by genetic analysis, may be the key to sight-preserving treatment.

Identical IFT140 Variants Cause Variable Skeletal Ciliopathy Phenotypes-Challenges for the Accurate Diagnosis.

Ciliopathies are rare congenital disorders, caused by defects in the cilium, that cover a broad clinical spectrum. A subgroup of ciliopathies showing significant phenotypic overlap are known as skeletal ciliopathies and include Jeune asphyxiating thoracic dysplasia (JATD), Mainzer-Saldino syndrome (MZSDS), cranioectodermal dysplasia (CED), and short-rib polydactyly (SRP). Ciliopathies are heterogeneous disorders with >187 associated genes, of which some genes are described to cause more than one ciliopathy phenotype. Both the clinical and molecular overlap make accurate diagnosing of these disorders challenging. We describe two unrelated Polish patients presenting with a skeletal ciliopathy who share the same compound heterozygous variants in IFT140 (NM_014,714.4) r.2765_2768del; p.(Tyr923Leufs*28) and exon 27-30 duplication; p.(Tyr1152_Thr1394dup). Apart from overlapping clinical symptoms the patients also show phenotypic differences; patient 1 showed more resemblance to a Mainzer-Saldino syndrome (MZSDS) phenotype, while patient 2 was more similar to the phenotype of cranioectodermal dysplasia (CED). In addition, functional testing in patient-derived fibroblasts revealed a distinct cilium phenotyps for each patient, and strikingly, the cilium phenotype of CED-like patient 2 resembled that of known CED patients. Besides two variants in IFT140, in depth exome analysis of ciliopathy associated genes revealed a likely-pathogenic heterozygous variant in INTU for patient 2 that possibly affects the same IFT-A complex to which IFT140 belongs and thereby could add to the phenotype of patient 2. Taken together, by combining genetic data, functional test results, and clinical findings we were able to accurately diagnose patient 1 with "IFT140-related ciliopathy with MZSDS-like features" and patient 2 with "IFT140-related ciliopathy with CED-like features". This study emphasizes that identical variants in one ciliopathy associated gene can lead to a variable ciliopathy phenotype and that an in depth and integrated analysis of clinical, molecular and functional data is necessary to accurately diagnose ciliopathy patients.

Homozygous microdeletion in the 11p13 region in the patient with isolated form of aniridia: New challenges in the genetic diagnostics of aniridia.

Aniridia is usually an autosomal dominant, rare disorder characterized by a variable degree of hypoplasia or the absence of iris tissue, with additional ocular abnormalities. Pathogenic variants in the PAX6 gene are associated with aniridia in most patients. However, in up to 30% of individuals, disease results from 11p13 chromosomal rearrangements. Here we present a patient with a clinical diagnosis of partial aniridia born to consanguineous Polish parents. The parents were asymptomatic and ophthalmologically normal. We performed PAX6 sequencing, array comparative genomic hybridization, quantitative real-time PCR, and whole genome sequencing. aCGH revealed a homozygous deletion of the DCDC1 gene fragment in the patient. The same, but heterozygous deletion, was detected in each of the patient's asymptomatic parents and brother. In the presented family, the signs and symptoms of aniridia are observed only in the homozygous proband. Whole genome sequencing analysis was performed to determine other possible causes of the disease and did not detect any additional or alternative potentially pathogenic variant. We report a novel homozygous deletion located in the 11p13 region, which does not include the PAX6 gene or any known PAX6 enhancers. To our best knowledge, this is the first reported case of a patient presented with isolated aniridia carrying a homozygous microdeletion downstream of the PAX6 gene.

The coincidence of two ultra-rare hereditary eye diseases: gyrate atrophy and Kjer optic atrophy - a surprising diagnosis based on next-generation sequencing.

Genetically determined ophthalmic diseases form a numerous and heterogenic group of disorders. Making the accurate clinical diagnosis of genetic eye disease is often a challenge for an ophthalmologist. In many cases, only genetic testing enables the establishment of the proper clinical diagnosis. Here we describe two ultra-rare diseases: gyrate atrophy of the choroid and retina (GACR) and Kjer-type optic atrophy coexisting in a 39-year-old Polish patient with severe visual impairment including a significant reduction of visual acuity and night blindness. Atrophic pigmented changes with large pigment deposits and chorioretinal atrophy with the retina's disturbed structure (with atrophic scarring changes and the epiretinal membrane) of both eyes were observed. Electroretinography (ERG) revealed extinguished responses. A Next-Generation Sequencing (NGS) panel comprising 275 retinal genes revealed a presence of potentially pathogenic variants in two genes: a homozygous variant c.1058G>A (p.Gly353Asp) in the OAT gene and a heterozygous variant c.1886C>G (p.Ser629Ter) in the OPA1 gene. The diagnosis established based on NGS is surprising because initially, several different diagnoses have been made, including high degenerative myopia, choroideremia, Leber congenital amaurosis, and severe, atypical retinitis pigmentosa. This report provides the unquestioned diagnostic value of the combination of chorioretinal imaging and the NGS technique. To our knowledge, this is the first and the only description of the coincidence of gyrate atrophy and Kjer-type optic atrophy.

Non-syndromic anophthalmia/microphthalmia can be caused by a PORCN variant inherited in X-linked recessive manner.

Anophthalmia and microphthalmia (A/M) represent severe developmental ocular malformations, corresponding, respectively, to absent eyeball or reduced size of the eye. Both anophthalmia and microphthalmia may occur in isolation or as part of a syndrome. Genetic heterogeneity has been demonstrated, and many genes have been reported to be associated with A/M. The advances in high-throughput sequencing have proven highly effective in defining the molecular basis of A/M. Nevertheless, there are still many patients with unsolved genetic background of the disease, who pose a significant challenge in the molecular diagnostics of A/M. Here we describe a family, with three males affected with the non-syndromic A/M. Whole exome-sequencing performed in Patient 1, revealed the presence of a novel probably pathogenic variant c.734A>G, (p.[Tyr245Cys]) in the PORCN gene. Pedigree analysis and segregation of the identified variant in the family confirmed the X-linked recessive pattern of inheritance. This is the first report of X-linked recessive non-syndromic A/M. Until now, pathogenic variants in the PORCN gene have been identified in the patients with Goltz syndrome, but they were inherited in X-linked dominant mode. The ocular phenotype is the only finding observed in the patients, which allows to exclude the diagnosis of Goltz syndrome.

Novel gene variants in Polish patients with Leber congenital amaurosis (LCA).

BACKGROUND: Leber congenital amaurosis (LCA) is a rare retinal disease that is the most frequent cause of congenital blindness in children and the most severe form of inherited retinal dystrophies. To date, 25 genes have been implicated in the pathogenesis of LCA. As gene therapy is becoming available, the identification of potential treatment candidates is crucial. The aim of the study was to report the molecular basis of Leber congenital amaurosis in 22 Polish families. METHODS: Single Nucleotide Polymorphism-microarray for LCA genes or Next Generation Sequencing diagnostic panel for LCA genes (or both tests) were performed to identify potentially pathogenic variants. Bidirectional Sanger sequencing was carried out for validation and segregation analysis of the variants identified within the families. RESULTS: The molecular background was established in 22 families. From a total of 24 identified variants, 23 were predicted to affect protein-coding or splicing, including 10 novel variants. The variants were identified in 7 genes: CEP290, GUCY2D, RPE65, NMNAT1, CRB1, RPGRIP1, and CRX. More than one-third of the patients, with clinical LCA diagnosis confirmed by the results of molecular analysis, appeared to be affected with a severe form of the disease: LCA10 caused by the CEP290 gene variants. Intronic mutation c.2991+1655A>G in the CEP290 gene was the most frequent variant identified in the studied group. CONCLUSIONS: This study provides the first molecular genetic characteristics of patients with Leber congenital amaurosis from the previously unexplored Polish population. Our study expands the mutational spectrum as we report 10 novel variants identified in LCA genes. The fact that the most frequent causes of the disease in the studied group of Polish patients are mutations in one out of three genes that are currently the targets for gene therapy (CEP290, GUCY2D, and RPE65) strongly emphasizes the importance of the molecular background analyses of LCA in Polish patients.

Prenatal genetic diagnosis of cranioectodermal dysplasia in a Polish family with compound heterozygous variants in WDR35.

The ciliary chondrodysplasias represent a group of clinically and genetically heterogeneous disorders that affect skeleton development. Cilia are organelles that project from the surface of many cell types and play an important role during prenatal and postnatal human development. Cranioectodermal dysplasia (Sensenbrenner syndrome, CED) is a ciliopathy primarily characterized by craniofacial, skeletal, and ectodermal abnormalities. To date six genes have been associated with CED: IFT122, WDR35, WDR19, IFT140, IFT43, and IFT52. Prenatal diagnosis of CED is challenging, and genetic testing can facilitate making a correct diagnosis. Here, we report on a family with two male siblings affected by CED: a 3.5 year-old patient and his 2 year-old brother. Molecular analysis of the proband at 1 year of age revealed compound heterozygous variants in WDR35: c.3G>A [p.(Met1-Ala30delinsMetfsTer4)] and c.2522A>T [p.(Asp841Val)]. Ultrasound examination during the second pregnancy revealed an increased nuchal translucency of 4.5 mm and a hypoplastic nasal bone at 12 weeks of gestation. Prenatal diagnostic testing was offered because of an increased risk for chromosomal abnormalities and recurrence risk for CED. Prenatal genetic analysis of a chorionic villus sample detected the WDR35 variants previously identified in the elder brother. This is the first report of a prenatal genetic diagnosis in CED.

Mitochondrial genome variation in male LHON patients with the m.11778G > A mutation.

Leber hereditary optic neuropathy (LHON) is a mitochondrial disorder with symptoms limited to a single tissue, optic nerve, resulting in vision loss. In the majority of cases it is caused by one of three point mutations in mitochondrial DNA (mtDNA) but their presence is not sufficient for disease development, since ~50% of men and ~10% women who carry them are affected. Thus additional modifying factors must exist. In this study, we use next generation sequencing to investigate the role of whole mtDNA variation in male Polish patients with LHON and m.11778G > A, the most frequent LHON mutation. We present a possible association between mtDNA haplogroup K and variants in its background, a combination of m.3480A > G, m.9055G > A, m.11299 T > C and m.14167C > T, and LHON mutation. These variants may have a negative effect on m.11778G > A increasing its penetrance and the risk of LHON in the Polish population. Surprisingly, we did not observe associations previously reported for m.11778G > A and LHON in European populations, particularly for haplogroup J as a risk factor, implying that mtDNA variation is much more complex. Our results indicate possible contribution of novel combination of mtDNA genetic factors to the LHON phenotype.