A Strong Candidate Gene for Nonsyndromic Intellectual Disability Phenotype: SGSM3.

SGSM proteins are small modulator proteins interacting with proteins in the RAS signaling pathway. Studies with mouse and human tissues indicated that SGSM genes were highly expressed in the brain and could be expressed at different levels at different stages of development in fetal and adult brain tissue. It was first reported by Birnbaum et al. that the SGSM3 gene might be associated with a Mendelian inherited disease in families of Ashkenazi Jews with clinical manifestations of intellectual disability (ID). In this study, a novel homozygous stop-gain (NM_015705.6: c.1576C>T: p.(Arg526Ter)) variation was detected in the SGSM3 gene in two siblings with short stature and ID findings. The report of two cases with bi-allelic LOF variants in the SGSM3 gene from different populations with similar clinical manifestations strengthens the potential of this gene as a candidate gene for the nonsyndromic ID phenotype. Functional studies are required to investigate the signaling pathways affected by SGSM3 gene variations to produce the ID phenotype and their effect on the functioning of neurons.

Biallelic Deletion of PEX26 Exon 4 in a Boy with Phenotypic Features of both Zellweger Syndrome and Infantile Refsum Disease.

Introduction: Peroxisome biogenesis disorders (PBDs) encompass a group of diseases marked by clinical and genetic heterogeneity. Phenotypes linked to PBDs include Zellweger syndrome, neonatal adrenoleukodystrophy, infantile Refsum disease (IRD), rhizomelic chondrodysplasia punctata type 1, and Heimler syndrome. PBD phenotypes manifest through hypotonia, developmental delay, facial dysmorphism, seizures, liver dysfunction, sensorineural hearing loss, and retinal dystrophy. Methods: The proband underwent comprehensive clinical evaluation, followed by whole-exome sequencing (WES) coupled with copy number analysis (CNV), aimed at identifying potential disease-causing variants aligning with the observed phenotype. Results: Our findings detail an individual exhibiting developmental delay, hearing loss, visual impairment, hepatomegaly, and splenomegaly, attributed to a biallelic deletion of exon 4 in the PEX26 gene. The WES analysis of the index case did not uncover any pathogenic/likely pathogenic single-nucleotide variations that could account for the observed clinical findings. However, the CNV data derived from WES revealed a homozygous deletion in exon 4 of the PEX26 gene (NM_001127649.3), providing a plausible explanation for the patient's clinical features. The exon 4 region of PEX26 encodes the transmembrane domain of the protein. The transmembrane domain plays a crucial role in anchoring the protein within lipid bilayers, and its absence can disrupt proper localization and functioning. As a result, this structural alteration may impact the protein's ability to facilitate essential cellular processes related to peroxisome biogenesis and function. Conclusion: The index patient, which presented with hearing loss, retinal involvement and hepatic dysfunction in adolescence age, has atypical clinical course that can be considered unusual for Zellweger syndrome (ZS) and IRD phenotypes, and its rare genotypic data (in-frame single exon deletion) expands the PBD disease spectrum. This study revealed for the first time that PEX26 protein transmembrane domain loss exhibits an unusual course with clinical findings of IRD and ZS phenotypes. WES studies, incorporating CNV analyses, empower the identification of novel genetic alterations in genes seldom associated with gross deletion/duplication variations, such as those in the PEX26 gene. This not only enhances diagnostic rates in rare diseases but also contributes to broadening the spectrum of causal mutations.

Genetic analyses in a cohort of pediatric patients with congenital hypothyroidism based on congenital hypothyroidism consensus guideline.

INTRODUCTION: Pathogenic variants in the genes involved in the formation of thyroid tissue and thyroid hormone secretion have been reported to cause congenital hypothyroidism (CH) in some cases. This study aimed to evaluate the clinical and genetic findings of CH cases thought to be due to genetic variants. METHODS: The study included cases whose genetic analysis was performed in accordance with the Congenital Hypothyroidism: A 2020-2021 Consensus Guidelines Update Guidelines recommendations criteria and analyzed them using the next-generation sequencing panel. RESULTS: 61 Turkish patients from 45 families were included in the study. The overall frequency of variant detection was 37.7% (Out of 45 families, 17 had a positive mutation). Segregation was carried out for all families with positive variants. Variants in the TPO gene are the most frequently encountered, and this situation was identified in 10 families. Variants followed this in the TSHR gene in 7 families, variants in the DUOX2 gene in 5 families, and two variants in the TG and NKX2-1 genes in 2 families each, which are six novel variants. Furthermore, among the NKX2-1 cases, one had thyroid involvement only, while the other had chorea only. We did not find differences between cases with detected mutations and mutation-negative cases regarding gender, neonatal/perinatal parameters, initial thyroid function values, and thyroid morphology. CONCLUSION: In the current investigation, rare new variations in genes known to be related to CH were discovered, adding to the molecular genetic spectrum. When we compare the overall variant detection frequency, the selection criterion for genetic analysis based on the current guidelines is quite rational, considering the benefits and costs, on the other hand, present in new genes awaiting discovery. Also, TSHR mutations are likely to be common and may account for more than 5% of thyroid dysgenesis cases if we include non-familial thyroid dysgenesis.

Smith-Lemli-Opitz Syndrome with Biallelic c.1295A>G (p.Tyr432Cys) Variant in the DHCR7 Gene in a 73-Year-Old Woman: Report of the Oldest Patient.

Introduction: Smith-Lemli-Opitz syndrome (SLOS), a genetic developmental disorder characterized by various congenital anomalies, arises from a loss of normal DHCR7 enzymatic action in cholesterol biosynthesis. This syndrome is typically marked by various congenital anomalies, including microcephaly with cognitive impairments, distinctive facial features, and syndactyly of the toes (2-3 fusion). Case Presentation: A 73-year-old woman, followed up on by the neurology clinic for the last 3 years for amnesia and movement disorders, was referred to our clinic for genetic etiology investigation. Although there were no significant dysmorphic findings on her physical examination, observations included partial syndactyly between the second and third toes of both feet, a wide forehead, and a triangular face. We used the whole-exome sequencing (WES) analysis to evaluate the patient because of their various phenotype, which included dysmorphic features, movement problems, recurrent hip dislocation, mild intellectual impairment. WES analysis revealed a homozygous missense c.1295A>G (p.Tyr432Cys) variation in DHCR7 gene. Discussion: A total of 9 patients with p.Tyr432Cys variant have been reported in the literature so far. The present case is the first patient with biallelic c.1295A>G (p.Tyr432Cys) variation in DHCR7 gene in the current literature. Diagnosing the disorder can be challenging, particularly in its milder manifestations, given the extensive range of clinical presentations. The present case is the oldest patient with SLOS reported in the relevant literature. Mild dysmorphic features, mild intellectual disability, and recurrent hip dislocation, along with the typical finding of syndactyly between the second and third toes in the foot, may indicate mild forms of SLOS.

Secondary findings in genes related to cancer phenotypes in Turkish exome sequencing data from 2020 individuals.

Big data generated from exome sequencing (ES) and genome sequencing (GS) analyses can be used to detect actionable and high-penetrance variants that are not directly associated with the primary diagnosis of patients but can guide their clinical follow-up and treatment. Variants that are classified as pathogenic/likely pathogenic and are clinically significant but not directly associated with the primary diagnosis of patients are defined as secondary findings (SF). The aim of this study was to examine the frequency and variant spectrum of cancer-related SF in 2020 Turkish ES data and to discuss the importance of the presence of cancer-related SF in at-risk family members in terms of genetic counseling and follow-up. A total of 2020 patients from 2020 different families were evaluated by ES. SF were detected in 28 unrelated cases (1.38%), and variants in BRCA2 (11 patients) and MLH1 (4 patients) genes were observed most frequently. A total of 21 different variants were identified, with 4 of them (c.9919_9932del and c.3653del in the BRCA2 gene, c.2002A>G in the MSH2 gene, c.26_29del in the TMEM127 gene) being novel variations. In three different families, c.1189C>T (p.Gln397*) variation in BRCA2 gene was detected, suggesting that this may be a common variant in the Turkish population. This study represents the largest cohort conducted in the Turkish population, examining the frequency and variant spectrum of cancer-related SF. With the identification of frequent variations and the detection of novel variations, the findings of this study have contributed to the variant spectrum. Genetic testing conducted in family members is presented as real-life data, showcasing the implications in terms of counseling, monitoring, and treatment through case examples.

Somatic STK11 mosaicism in a Turkish patient with Peutz-Jeghers syndrome.

Peutz-Jeghers syndrome (PJS) is an autosomal dominant disorder, caused by germline variants in the serine/threonine kinase 11 (STK11) gene. However, mosaic variants in STK11 gene have been rarely described. A 25-year-old woman diagnosed with PJS due to multiple hamartomatous polyps in the gastrointestinal tract was referred to our clinic. In the molecular diagnosis, the patient was evaluated using the STK11 gene sequence analysis and multiplex ligation-dependent probe amplification (MLPA) method, which suggested no pathogenic variant to account for the clinical picture. Given that the clinical findings of the patient were consistent with those of PJS, the raw data from next-generation sequencing (NGS) were re-examined for mosaicism which led to the detection of a novel mosaic c.920 + 1G > T variant in STK11 gene with a rate of 23% (1860x). Deep read-level NGS was performed on buccal mucosa and polyp samples to determine mosaicism levels in other tissues. Variant frequencies were 29% (710x) and 31% (1301x), respectively. Mosaicism should be considered in cases with clear clinical diagnostic criteria, such as PJS, where the pathogenic variant cannot be detected by sequence analysis and MLPA methods. Identification of mosaicism in these patients is very important as it can have an impact on patient follow-up and genetic counseling for relatives.

Severe Early-Onset Obesity and Diabetic Ketoacidosis due to a Novel Homozygous c.169C>T p.Arg57* Variant in CEP19 Gene.

Introduction: Early-onset severe obesity is usually the result of an underlying genetic disorder, and several genes have recently been shown to cause syndromic and nonsyndromic forms of obesity. The "centrosomal protein 19 (CEP19)" gene encodes for a centrosomal and ciliary protein. Homozygous variants in the CEP19 gene are extremely rare causes of early-onset severe monogenic obesity. Herein, we present a Turkish family with early-onset severe obesity with variable features. Methods: Sanger sequencing and whole-exome sequencing were performed to identify the genetic etiology in the family. Results: The index case was a 12-year-old female who presented with severe obesity (BMI of 62.7 kg/m2), metabolic syndrome, and diabetic ketoacidosis. Her nonidentical twin female siblings also had early-onset severe obesity, metabolic syndrome, and diabetes. In addition, one of the affected siblings had situs inversus abdominalis, polysplenia, lumbar vertebral fusion, and abnormal lateralization. A novel homozygous nonsense (c.169C>T, p. Arg57*) pathogenic variant was detected in exon 3 of the CEP19 gene in all affected members of the family. One unaffected sister and unaffected parents were heterozygous for the variant. This variant is predicted to cause a stop codon at amino acid sequence 57, leading to a truncated CEP19 protein. Discussion/Conclusion: Our study expands the phenotypical manifestations and variation database of CEP19 variants. The findings in one of our patients reaffirm its role in the assembly and function of both motile and immotile cilia.

Natural history of ENPP1 deficiency: Nationwide Turkish Cohort Study of autosomal-recessive hypophosphataemic rickets type 2.

OBJECTIVE: Autosomal-recessive hypophosphataemic rickets type 2 (ARHR2) is a rare disease that is reported in survivors of generalized arterial calcification of infancy (GACI). DESIGN, PATIENTS AND MEASUREMENT: The objective of this study was to characterize a multicenter paediatric cohort with ARHR2 due to ectonucleotide pyrophosphatase/phosphodiesterase family member 1 (ENPP1) deficiency and with a diagnosis of GACI or GACI-related findings. The clinical, biochemical and genetic characteristics of the patients were retrospectively retrieved. RESULTS: We identified 18 patients from 13 families diagnosed with ARHR2. Fifteen of the patients had an ENPP1 variation confirmed with genetic analyses, and three were siblings of one of these patients, who had clinically diagnosed hypophosphataemic rickets (HRs) with the same presentation. From nine centres, 18 patients, of whom 12 (66.7%) were females, were included in the study. The mean age at diagnosis was 4.2 ± 2.2 (1.6-9) years. The most frequently reported clinical findings on admission were limb deformities (66.6%) and short stature (44.4%). At diagnosis, the mean height SD was -2.2 ± 1.3. Five of the patients were diagnosed with GACI in the neonatal period and treated with bisphosphonates. Other patients were initially diagnosed with ARHR2, but after the detection of a biallelic variant in the ENPP1 gene, it was understood that they previously had clinical findings associated with GACI. Three patients had hearing loss, and two had cervical fusion. After the treatment of HRs, one patient developed calcification, and one developed intimal proliferation. CONCLUSION: ARHR2 represents one manifestation of ENPP1 deficiency that usually manifests later in life than GACI. The history of calcifications or comorbidities that might be associated with GACI will facilitate the diagnosis in patients with ARHR2, and patients receiving calcitriol and phosphate medication should be carefully monitored for signs of calcification or intimal proliferation.

A Rare Presentation of Homozygous Pathogenic Variant in MC2R Gene with Salt-Wasting Crisis in a Neonate.

Introduction: Familial glucocorticoid deficiency (FGD) is a rare autosomal recessive disease resulting from isolated glucocorticoid deficiency or unresponsiveness to adrenocorticotropic hormone. Patients with FGD usually present in infancy or early childhood with hyperpigmentation, recurrent infections, and hypoglycemia. The salt-wasting crisis is rare. Case Presentation: A term female neonate was admitted to the neonatal intensive care unit due to respiratory distress. On physical examination, she had generalized hyperpigmentation. Initial laboratory work-up yielded normal serum electrolytes and glucose. Hyponatremia and hyperkalemia emerged on follow-up. The patient was diagnosed as having primary adrenal insufficiency (PAI) with elevated plasma adrenocorticotropin hormone and reduced cortisol levels and hydrocortisone. We started on oral sodium (5 mEq/kg/day) and fludrocortisone (FC) (0.2 mg/day) treatment to the patient. Ultrasonography revealed hypoplastic adrenal glands. Molecular genetic analysis revealed a previously reported homozygous pathogenic variant NM_000529.2: c.560delT (p.V187fs*29) in the MC2R gene. FC dose was tapered to 0.05 mg/day on the third month of life and was stopped at tenth months of age with maintenance of normal serum electrolytes and clinical findings. Conclusion: FGD due to MC2R gene mutation may rarely present with a salt-wasting crisis in the neonatal period. Identifying the causative gene with the pathogenic variant in PAI may serve to individualize a treatment plan.

Expanding the clinical and genetic landscape of (developmental) epileptic encephalopathy with spike-and-wave activation in sleep: results from studies of a Turkish cohort.

The terms developmental epileptic encephalopathy with spike-and-wave activation in sleep (DEE-SWAS) and epileptic encephalopathy with spike-and-wave activation in sleep (EE-SWAS) designate a spectrum of conditions that are typified by different combinations of motor, cognitive, language, and behavioral regression linked to robust spike-and-wave activity during sleep. In this study, we aimed at describing the clinical and molecular findings in "(developmental) epileptic encephalopathy with spike-and-wave activation in sleep" (D)EE-SWAS) patients as well as at contributing to the genetic etiologic spectrum of (D)EE-SWAS. Single nucleotide polymorphism (SNP) array and whole-exome sequencing (WES) techniques were used to determine the underlying genetic etiologies. Of the 24 patients included in the study, 8 (33%) were female and 16 (67%) were male. The median age at onset of the first seizure was 4 years and the median age at diagnosis of (D)EE-SWAS was 5 years. Of the 24 cases included in the study, 13 were compatible with the clinical diagnosis of DEE-SWAS and 11 were compatible with the clinical diagnosis of EE-SWAS. Abnormal perinatal history was present in four cases (17%), and two cases (8%) had a family history of epilepsy. Approximately two-thirds (63%) of all patients had abnormalities detected on brain computerized tomography/magnetic resonance (CT/MR) imaging. After SNP array and WES analysis, the genetic etiology was revealed in 7 out of 24 (29%) cases. Three of the variants detected were novel (SLC12A5, DLG4, SLC9A6). This study revealed for the first time that Smith-Magenis syndrome, SCN8A-related DEE type 13 and SLC12A5 gene variation are involved in the genetic etiology of (D)EE-SWAS. (D)EE-SWAS is a genetically diverse disorder with underlying copy number variations and single-gene abnormalities. In the current investigation, rare novel variations in genes known to be related to (D)EE-SWAS and not previously reported genes to be related to (D)EE-SWAS were discovered, adding to the molecular genetic spectrum. Molecular etiology enables the patient and family to receive thorough and accurate genetic counseling as well as a personalized medicine approach.

The first Turkish family with a novel biallelic missense variant of the ALKBH8 gene: A study on the clinical and variant spectrum of ALKBH8-related intellectual developmental disorders.

ABH8, the protein encoded by the ALKBH8 gene, modifies tRNAs by methylating their anticodon wobble uridine residues. The variations in the ALKBH8 gene are associated with the "intellectual developmental disorder, autosomal recessive type 71" (MIM: 618504) phenotype in the OMIM database. This phenotype is characterized by global developmental delay, facial dysmorphic features, and psychiatric problems. To date, 12 patients from five distinct families carrying variants of the ALKBH8 gene have been reported in the literature. In the present study, we report the first Turkish family harboring a novel homozygous missense variant, NM_138775.3:c.1874G > C (p.Arg625Pro), in the last exon of the ALKBH8 gene. Two affected siblings in this family showed signs of global developmental delay and intellectual disability. Based on the dysmorphological assessment of the cases, fifth finger clinodactyly and fetal fingertip pads were prominent, in addition to the dysmorphic findings similar to those reported in previous studies. Minor dysmorphic limb anomalies in relation to this phenotype have not yet been previously reported in the literature. Our computational studies revealed the potential deleterious effects of the Arg-to-Pro substitution on the structure and stability of the ABH8 methyltransferase domain. In the present report, the first Turkish family with an ultrarare disease associated with the ALKBH8 gene was reported, and a novel deleterious variant in the ALKBH8 gene and additional clinical features that were not reported with this condition have been reported.

Prediction of molecular phenotypes for novel SCN1A variants from a Turkish genetic epilepsy syndromes cohort and report of two new patients with recessive Dravet syndrome.

Dravet syndrome and genetic epilepsy with febrile seizures plus (GEFS+) are both epilepsy syndromes that can be attributed to deleterious mutations occurring in SCN1A, the gene encoding the pore-forming α-subunit of the NaV 1.1 voltage-gated sodium channel predominantly expressed in the central nervous system. In this research endeavor, our goal is to expand our prior cohort of Turkish patients affected by SCN1A-positive genetic epilepsy disorders. This will be accomplished by incorporating two recently discovered and infrequent index cases who possess a novel biallelic (homozygous) SCN1A missense variant, namely E158G, associated with Dravet syndrome. Furthermore, our intention is to use computational techniques to predict the molecular phenotypes of each distinct SCN1A variant that has been detected to date within our center. The correlation between genotype and phenotype in Dravet syndrome/GEFS+ is intricate and necessitates meticulous clinical investigation as well as advanced scientific exploration. Broadened mechanistic and structural insights into NaV 1.1 dysfunction offer significant promise in facilitating the development of targeted and effective therapies, which will ultimately enhance clinical outcomes in the treatment of epilepsy.

Lunapark deficiency leads to an autosomal recessive neurodevelopmental phenotype with a degenerative course, epilepsy and distinct brain anomalies.

LNPK encodes a conserved membrane protein that stabilizes the junctions of the tubular endoplasmic reticulum network playing crucial roles in diverse biological functions. Recently, homozygous variants in LNPK were shown to cause a neurodevelopmental disorder (OMIM#618090) in four patients displaying developmental delay, epilepsy and nonspecific brain malformations including corpus callosum hypoplasia and variable impairment of cerebellum. We sought to delineate the molecular and phenotypic spectrum of LNPK-related disorder. Exome or genome sequencing was carried out in 11 families. Thorough clinical and neuroradiological evaluation was performed for all the affected individuals, including review of previously reported patients. We identified 12 distinct homozygous loss-of-function variants in 16 individuals presenting with moderate to profound developmental delay, cognitive impairment, regression, refractory epilepsy and a recognizable neuroimaging pattern consisting of corpus callosum hypoplasia and signal alterations of the forceps minor ('ear-of-the-lynx' sign), variably associated with substantia nigra signal alterations, mild brain atrophy, short midbrain and cerebellar hypoplasia/atrophy. In summary, we define the core phenotype of LNPK-related disorder and expand the list of neurological disorders presenting with the 'ear-of-the-lynx' sign suggesting a possible common underlying mechanism related to endoplasmic reticulum-phagy dysfunction.

Frequency of Familial Mediterranean Fever Gene Mutation in Patients Presenting With Joint Pain and Diagnosed With Acute Rheumatic Fever.

Introduction Acute rheumatic fever (ARF) is a non-suppurative systemic inflammatory disease that manifests 1-5 weeks following a Group A beta-hemolytic streptococcal infection. On the other hand, familial Mediterranean fever (FMF) is a hereditary autoinflammatory disease characterized as an autosomal recessive disease, with affected individuals having pathogenic mutations in the Mediterranean fever gene (MEFV) gene located on the short arm of chromosome 16. FMF and ARF have overlapping symptoms and signs, and both disorders are common in Turkey. In ARF, the target organ is the heart, while in FMF, the target organ is the kidney; both organs can benefit from prophylactic measures. Our study aims to determine the frequency of the FMF gene mutation in patients with ARF in Turkey and detect any overlapping conditions. Method Patients who were diagnosed with a first-attack ARF between May 2015 and May 2018 were retrospectively screened. Patients who underwent MEFV gene analysis considering FMF in the differential diagnosis were included in the study. Results In this study, no statistical difference was found between the presence of MEFV gene mutations, carditis, high anti-streptolysin-O antibody (ASO) levels, and the groups with monoarthritis, polyarthritis, and polyarthralgia (p >0.05). Conclusions In conclusion, patients with ARF should be evaluated for FMF to avoid irreversible complications.

Expanding the clinical and immunological phenotypes of PAX1-deficient SCID and CID patients.

Paired box 1 (PAX1) deficiency has been reported in a small number of patients diagnosed with otofaciocervical syndrome type 2 (OFCS2). We described six new patients who demonstrated variable clinical penetrance. Reduced transcriptional activity of pathogenic variants confirmed partial or complete PAX1 deficiency. Thymic aplasia and hypoplasia were associated with impaired T cell immunity. Corrective treatment was required in 4/6 patients. Hematopoietic stem cell transplantation resulted in poor immune reconstitution with absent naïve T cells, contrasting with the superior recovery of T cell immunity after thymus transplantation. Normal ex vivo differentiation of PAX1-deficient CD34+ cells into mature T cells demonstrated the absence of a hematopoietic cell-intrinsic defect. New overlapping features with DiGeorge syndrome included primary hypoparathyroidism (n = 5) and congenital heart defects (n = 2), in line with PAX1 expression during early embryogenesis. Our results highlight new features of PAX1 deficiency, which are relevant to improving early diagnosis and identifying patients requiring corrective treatment.

Identification of novel variants in Turkish families with non-syndromic congenital cataracts using whole-exome sequencing.

PURPOSE: The present study aimed to identify the molecular etiology of non-syndromic congenital cataract (CC) using whole-exome sequencing (WES) analysis. METHODS: In the present study, ophthalmologic results and pedigree analysis of the families of 12 patients with non-syndromic CC were evaluated. WES analysis was conducted after DNA was isolated from peripheral blood samples obtained from the patients. RESULTS: Twelve non-syndromic probands (10 males and 2 females) with bilateral CC were included in the study. Patient age ranged between 1 and 11 months. WES analysis showed pathogenic/likely pathogenic variant in 7 (58%) of the 12 families and variant of unknown significance (VUS) in 5 (42%) of them. All the 13 different variants detected in 9 different CC-related genes were co-segregated with the disease. Autosomal dominant inheritance was found in 7 (58%) of the families and autosomal recessive inheritance was found in 5 (42%) of them. CONCLUSION: To the best of our knowledge, the present research is one of the limited numbers of studies in the Turkish population in which genetically heterogeneous non-syndromic CC was investigated using WES analysis. Novel variants that we identified in DNMBP, LSS, and WFS1 genes, which are rarely associated with the CC phenotype, have contributed to the mutation spectrum of this disease. Identifying the relevant molecular genetic etiology allows accurate genetic counseling to be provided to the families.

The New Youngest Case of Grange Syndrome with a Novel Biallelic Pathogenic Variant in YY1AP1.

Introduction: Grange syndrome (OMIM 602531) is characterized by a constellation of symptoms of hypertension, stenosis, or occlusion of different arteries (including the cerebral, renal, abdominal, and coronary vessels) with a variable occurrence of brachysyndactyly, bone fragility, and congenital heart defects. Learning disabilities were also reported in some cases. Biallelic pathogenic variants in YY1AP1 are associated with the syndrome. Only 14 individuals with this ultra-rare syndrome (12 of them were molecularly confirmed) have hitherto been reported in the literature. Case Presentation: We herein describe a 11/2-year-old additional female case of Grange syndrome with hypertension, patent ductus arteriosus, and brachysyndactyly who was subsequently confirmed to carry a novel homozygous frameshift variant (c.2291del; p.Pro764Leufs*12) in the YY1AP1 gene through whole-exome sequencing. Conclusion: This report extends the allelic spectrum in Grange syndrome and helps provide insight into the potential role of YY1AP1 in the regulation of cellular processes.

Pyrroline-5-carboxylate reductase 2 (PYCR2) deficiency causes hereditary spastic paraplaegia in late childhood.

OBJECTIVES: PYCR2 gene variants are extremely rare condition which is associated with hypomyelinating leukodystrophy type 10 with microcephaly (HLD10). The aim of the present study is to report the clinical findings of patients having novel PYCR2 gene variant that manifest Hereditary Spastic Paraplegia (HSP) is the only symptom without hypomyelinating leukodystrophy. This is the first study that report the PYCR2 gene variants as a cause of HSP in late childhood. We believe it can contribute to expanding the spectrum of the phenotypes associated with PYCR2. METHODS: It is a retrospective study. Of the patients with similar clinical features from two related families, "patient 1" was designated as the index case, and was analyzed using Whole Exome Squence analysis (WES). The detected variation was investigated in the index case's parents, relatives, and sibling with a similar phenotype. Clinical, brain magnetic resonance (MR) images and MR spectroscopic findings of the patients were reported. RESULTS: A novel homozygous missense (NM_013328: c.383T > C, p.V128A) variant in the PYCR2 gene is detected in 5 patient from 2 related families. All the patients were male, their ages ranges from 6 to 26 years (15.58 ± 8,33 yrs). Developmantal milestones were normal without dysmorphic features. 4 (%80) patients exhibit mild intention tremor started at the age of approximately 6 years of age. 4 (%80) patients had gait difficulty and progressive lower limb spasticity started at the age of 8-12 years. White matter myelination was normal in all patients. Glycine peakes were detected on the MR spectroscopy in all patients. CONCLUSION: Some variants of PYCR2 gene are responsible for causing clinical features of HSP without hypomyelinating leukodystrophy in the pediatric patients.