Characterisation and prevalence of inherited retinal diseases in the Finnish population reveals enrichment of population-specific phenotypes and causative variants.

Aims: This study aims to assess clinical and genetic characteristics as well as the prevalence of inherited retinal dystrophies (IRD) and their subphenotypes in the Finnish founder population.

Methods: A retrospective analysis of clinical and genetic data from Northern Finnish patients diagnosed with IRD between 1996 and 2023 at Oulu University Hospital, Finland, was conducted.

Results: The cohort comprised 582 patients with IRD, categorised into 16 different subphenotypes.

Phenotypic Heterogeneity in Genetic and Acquired Pediatric Cerebellar Disorders.

Background: The genetic landscape of pediatric cerebellar disorders (PCDs) in Finland is undefined.

Objectives: The objective was to define epidemiological, clinical, neuroradiological, and genetic characteristics of PCDs in Northern Finland.

Methods: A longitudinal population-based cohort study of children with a movement disorder or a cerebellar malformation (diagnosis ≤16 years; study period 1970-2022) was performed in the tertiary catchment area of the Oulu University Hospital, Finland.

Novel MYH10 heterozygous variants associated to a syndrome combining mainly ptosis and ocular coloboma expand the MYH10 related phenotypes.

Syndromes associating both eyeball and periocular developmental anomalies, combining iris chorioretinal (ocular) coloboma and ptosis, are described in very rare clinical entities such as Baraitser-Winter cerebrofrontofacial syndrome (BWCFF). We report on six individuals from 3 unrelated families presenting with autosomal dominant eye malformations, including ocular coloboma, ptosis and craniofacial features suggesting BWCFF. However, no neurodevelopmental disorders (NDD) as usually observed in this syndrome were detected.

AUTS2-related syndrome: Insights from a large European cohort.

Purpose: AUTS2-related syndrome is characterized by developmental delay, autism spectrum disorder, and intellectual disability. From alternative promoters, AUTS2 encodes 2 distinct long and short isoforms encoding a putative transcriptional activator.

Methods: Through a European collaborative study, we collected clinical and genotype data on the largest AUTS2-related syndrome cohort of 58 patients harboring genomic rearrangements or single-nucleotide variants (SNVs).

Novel intronic variant in NDUFS7 gene results in mitochondrial complex I assembly defect with early basal ganglia and midbrain involvement with progressive neuroimaging findings.

Leigh syndrome is the most common phenotype of mitochondrial disorders in children. This study demonstrates clinical, neuroradiological, and molecular genetic findings in siblings with Leigh syndrome and isolated complex I assembly defect associated with intronic c.16 + 5G > A variant in the NDUFS7 gene.

Clinical and genetic characteristics and natural history of Finnish families with familial exudative vitreoretinopathy due to pathogenic FZD4 variants.

Purpose: To report clinical and genetic characteristics of familial exudative vitreoretinopathy (FEVR) in the Finnish population.

Methods: Detailed clinical and genetic data of 35 individuals with heterozygous pathogenic variants in FZD4 were gathered and analysed.

Results: Thirty-two individuals with FZD4 c.

A novel pathogenic missense variant in epilepsy of infancy with migrating focal seizures causes impaired KCC2 chloride extrusion.

The potassium-chloride co-transporter 2, KCC2, is a neuron-specific ion transporter that plays a multifunctional role in neuronal development. In mature neurons, KCC2 maintains a low enough intracellular chloride concentration essential for inhibitory neurotransmission. During recent years, pathogenic variants in the KCC2 encoding gene affecting the functionality or expression of the transporter protein have been described in several patients with epilepsy of infancy with migrating focal seizures (EIMFS), a devastating early-onset developmental and epileptic encephalopathy.

Report of a Novel Homozygous Intragenic Duplication and a Review of Literature of Developmental Split-Brain Syndrome aka Horizontal Gaze Palsy with Progressive Scoliosis-2 with Impaired Intellectual Development Syndrome.

Introduction: Horizontal gaze palsy with progressive scoliosis-2 (HGPPS2, MIM 617542) with impaired intellectual development aka developmental split-brain syndrome is an ultra-rare congenital disorder caused by pathogenic biallelic variants in the deleted in colorectal cancer () gene.

Case Presentation: We report the clinical and genetic characterization of a Syrian patient with a HGPPS2 phenotype and review the previously published cases of HGPPS2. The genetic screening was performed using exome sequencing on Illumina platform.

Biallelic hexokinase 1 (HK1) variants causative of non-spherocytic haemolytic anaemia: A case series with emphasis on the HK1 promoter variant and literature review.

The hexokinase (HK) enzyme plays a key role in red blood cell energy production. Hereditary non-spherocytic haemolytic anaemia (HNSHA) caused by HK deficiency is a rare disorder with only 12 different disease-associated variants identified. Here, we describe the clinical features and genotypes of four previously unreported patients with hexokinase 1 (HK1)-related HNSHA, yielding two novel truncating HK1 variants.

Detection of Copy-Number Variants in Mosaic Basal Cell Nevus Syndrome.

Basal cell nevus syndrome (BCNS) is an inherited disorder characterized mainly by the development of basal cell carcinomas (BCCs) at an early age. BCNS is caused by heterozygous small-nucleotide variants (SNVs) and copy-number variants (CNVs) in the Patched1 () gene. Genetic diagnosis may be complicated in mosaic BCNS patients, as accurate SNV and CNV analysis requires high-sensitivity methods due to possible low variant allele frequencies.

Infantile onset encephalomyopathy, retinopathy, optic atrophy, and mitochondrial DNA depletion associated with a novel pathogenic DHX16 variant.

We studied a patient with mitochondrial DNA depletion in skeletal muscle and a multiorgan phenotype, including fatal encephalomyopathy, retinopathy, optic atrophy, and sensorineural hearing loss. Instead of pathogenic variants in the mitochondrial maintenance genes, we identified previously unpublished variant in DHX16 gene, a de novo heterozygous c.1360C>T (p.

Jansen de Vries syndrome: Report of four new patients and review of the literature.

Jansen de Vries syndrome (JDVS, OMIM: 617450) is a rare neurodevelopmental disorder associated with hypotonia, behavioral features, high threshold to pain, short stature, ophthalmological abnormalities, dysmorphism and occasionally a structural cardiac condition. It is caused by truncating variants of the last and penultimate exons of PPM1D. So far, 21 patients with JVDS have been reported in the literature.

Pathogenic REST variant causing Jones syndrome and a review of the literature.

Jones syndrome is a rare dominantly inherited syndrome characterized by gingival fibromatosis and progressive sensorineural hearing loss becoming symptomatic in the second decade of life. Here, we report a father and his two daughters presenting with a typical Jones syndrome (OMIM %135550) phenotype. Exome sequencing identified a repressor element 1-silencing transcription factor (REST, OMIM *600571) (NM_005612.

The Finnish genetic heritage in 2022 - from diagnosis to translational research.

Isolated populations have been valuable for the discovery of rare monogenic diseases and their causative genetic variants. Finnish disease heritage (FDH) is an example of a group of hereditary monogenic disorders caused by single major, usually autosomal-recessive, variants enriched in the population due to several past genetic drift events. Interestingly, distinct subpopulations have remained in Finland and have maintained their unique genetic repertoire.

ATM c.7570G>C is a high-risk allele for breast cancer.

ATM is generally described as a moderate-risk breast cancer susceptibility gene. However, some of ATM variants might encounter higher risk. ATM c.

HIDEA syndrome is caused by biallelic, pathogenic, rare or founder P4HTM variants impacting the active site or the overall stability of the P4H-TM protein.

HIDEA syndrome is caused by biallelic pathogenic variants in P4HTM. The phenotype is characterized by muscular and central hypotonia, hypoventilation including obstructive and central sleep apneas, intellectual disability, dysautonomia, epilepsy, eye abnormalities, and an increased tendency to develop respiratory distress during pneumonia. Here, we report six new patients with HIDEA syndrome caused by five different biallelic P4HTM variants, including three novel variants.

Psychiatric symptoms in Salla disease.

Salla disease (SD) is a rare lysosomal storage disorder characterised by intellectual disability ataxia, athetosis, nystagmus, and central nervous system demyelination. Although the neurological spectrum of SD's clinical phenotype is well defined, psychotic symptoms in SD remain unreported. We reviewed the presence of psychiatric symptoms in patients diagnosed with SD.

A novel frameshift variant in associated with nonsyndromic retinitis pigmentosa, and a review of -related phenotypes.

Background: Pathogenic variants in the gene can present as atypical Usher syndrome or as retinitis pigmentosa. Here, we present a review of all reported cases of variants in the literature to date and present a novel variant of , c.1261_1262delinsA, in a consanguineous northern Finnish family with two individuals.