Further characterization of ARSK-related mucopolysaccharidosis type 10.

Mucopolysaccharidosis type 10 is caused by biallelic variants in ARSK, which encodes for a lysosomal sulfatase. To date, seven patients with a mild phenotype resembling spondyloepiphyseal dysplasia or multiple epiphyseal dysplasia have been described. In this report, we present two novel ARSK variants and report clinical and radiological findings of three patients. The patients' initial complaints were hip or knee pain and a waddling gait. All patients showed normal intelligence, normal hearing and eye examinations, and none had organomegaly. While typical dysostosis multiplex findings were not observed, mild platyspondyly with anterior beaking of some vertebral bodies, irregular vertebral endplates, wide ribs, inferior tapering of the ilea with a poorly developed acetabulum, irregularity of the central part of the femoral head, delayed ossification of the carpals were noted. Remarkably, all patients showed metaphyseal striation of the long bones, a crucial diagnostic clue to identify ARSK-related MPS type 10. Interestingly, vertebral involvement regressed during follow-up. On the other hand, hip dysplasia progressed in all patients. In conclusion, this study provides valuable long-term results on a recently discovered form of MPS.

The molecular spectrum of Turkish osteopetrosis and related osteoclast disorders with natural history, including a candidate gene, CCDC120.

BACKGROUND: Osteopetrosis and related osteoclastic disorders are a heterogeneous group of inherited diseases characterized by increased bone density. The aim of this study is to investigate the molecular spectrum and natural history of the clinical and radiological features of these disorders. METHODS: 28 patients from 20 families were enrolled in the study; 20 of them were followed for a period of 1-16 years. Targeted gene analysis and whole-exome sequencing (WES) were performed. RESULTS: Biallelic mutations in CLCN7 and TCIRG1 were detected in three families each, in TNFRSF11A and CA2 in two families each, and in SNX10 in one family in the osteopetrosis group. A heterozygous variant in CLCN7 was also found in one family. In the osteopetrosis and related osteoclast disorders group, three different variants in CTSK were detected in five families with pycnodysostosis and a SLC29A3 variant causing dysosteosclerosis was detected in one family. In autosomal recessive osteopetrosis (ARO), a malignant infantile form, four patients died during follow-up, two of whom had undergone hematopoietic stem cell transplantation. Interestingly, all patients had osteopetrorickets of the long bone metaphyses in infancy, typical skeletal features such as Erlenmeyer flask deformity and bone-in-bone appearance that developed toward the end of early childhood. Two siblings with a biallelic missense mutation in CLCN7 and one patient with the compound heterozygous novel splicing variants in intron 15 and 17 in TCIRG1 corresponded to the intermediate form of ARO (IARO); there was intrafamilial clinical heterogeneity in the family with the CLCN7 variant. One of two patients with IARO and distal tubular acidosis was found to have a large deletion in CA2. In one family, two siblings with a heterozygous mutation in CLCN7 were affected, whereas the father with the same mutation was asymptomatic. In WES analysis of three brothers from a family without mutations in osteopetrosis genes, a hemizygous missense variant in CCDC120, a novel gene, was found to be associated with high bone mass. CONCLUSION: This study extended the natural history of the different types of osteopetrosis and also introduced a candidate gene, CCDC120, potentially causing osteopetrosis.

Investigation of (Epi)genetic causes in syndromic short children born small for gestational age.

Intrauterine onset syndromic short stature constitutes a group of diseases that pose challenges in differential diagnosis due to their rarity and clinical as well as molecular heterogeneity. The aim of this study was to investigate the presence of (epi)genetic causes in children born small for gestational age (SGA) and manifesting clinically undiagnosed syndromic short stature. The study group comprised twenty-nine cases selected from the syndromic SGA cohort. Various analyses were performed, including chromosomal microarray (CMA), methylation-specific-multiple ligation probe amplification for chromosomes 6,14 and 20, and whole exome sequencing (WES). Pathogenic copy number variants (CNVs) on chromosomes 2q13, 22q11.3, Xp22.33, 17q21.31, 19p13.13 and 4p16.31 causing syndromic growth disturbance were detected in six patients. Maternal uniparental disomy 14 was identified in a patient. WES was performed in the remaining 22 patients, revealing pathogenic variants in nine cases; six were monoallelic (ACAN, ARID2, NIPBL, PIK3R1, SMAD4, BRIP1), two were biallelic (BRCA2, RFWD3) and one was hemizygous (HUWE1). Seven of these were novel. Craniofacial dysmorphism, which is an important clue for the diagnosis of syndromes, was very mild in all patients. This study unveiled, for the first time, that ARID2 mutatios can cause syndromic SGA. In conclusion, a high (55.2%) diagnosis rate was achieved through the utilization of CMA, epigenetic and WES analyzes; 15 rare syndromes were defined, who were born with SGA and had atypical and/or mild dysmorphic findings. This study not only drew attention to the association of some rare syndromes with SGA, but also introduced novel genes and CNVs as potential contributors to syndromic SGA.

Congenital Heart Defects and Outcome in a Large Cohort of Down Syndrome: A Single-Center Experience from Turkey.

OBJECTIVE: Congenital heart defects occur in approximately 50% of children with Down syndrome and they contribute considerably to morbidity and mortality. The aim of this study is to investigate the prevalence, classification, and survival of congenital heart defects in Down syndrome. MATERIALS AND METHODS: About 1731 Down syndrome patients who underwent echocardiography between 1986 and 2022 were evaluated. The median follow-up duration was 8.7 years (range 1-35.8 years). Congenital heart defect was grouped as cyanotic and acyanotic. RESULTS: Among the 1731 patients, 52.1% had congenital heart defects. Congenital heart defect was significantly more common in females than males. The most common cardiac defect was ventricular septal defect (35%), followed by atrial septal defect (31.8%), atrioventricular septal defect (23.4%), tetralogy of Fallot (5%), and patent ductus arteriosus (3.6%). In the follow-up, 43.2% of atrial septal defect, 17.8% of ventricular septal defect, and a total of 20% of congenital heart defects were closed spontaneously. About 34.4% of congenital heart defect was corrected by cardiac surgery/intervention. Five-year survival rate was 97.4% in patients without congenital heart defects, whereas it was 95.6% in mild congenital heart defects and 86.1% in moderate to severe congenital heart defects. There was no relationship between consanguinity, parental age, maternal disease, folic acid supplementation before/during pregnancy, gestational age, birth weight, and congenital heart defects. Neuromotor development was similar in patients with and without congenital heart defects. CONCLUSION: We demonstrated that almost half of the patients had congenital heart defects; ventricular septal defect was the most common congenital heart defect type. This study is valuable in terms of the largest single-center study describing the classification, prognostic factors, and survival of Down syndrome patients with congenital heart defect from Turkey.

Phenotypic and Molecular Spectrum of a Turkish Cohort with Hereditary Multiple Osteochondromas.

OBJECTIVE: Hereditary multiple osteochondromas is an autosomal dominant disorder caused by heterozygous pathogenic variants in EXT1 or EXT2. We aimed to evaluate the clinical and molecular findings of a Turkish cohort with hereditary multiple osteochondroma. MATERIALS AND METHODS: Thirty-two patients aged 1.3-49.6 years from 22 families were enrolled. Genetic analyses were made by EXT1 and/or EXT2 sequencing and chromosomal microarray analyses. RESULTS: We found 17 intragenic pathogenic variants in EXT1 (13/17) and EXT2 (4/17), 12 of which are novel. Four probands had EXT1 deletions, including 2 patients with partial EXT1 microdeletions involving exons 2-11 and 5-11, and 2 patients with whole-gene deletions. In 21 variants, the frequency of truncating and missense variants was 76.1% and 23.8%, respectively. Two families had no detectable variants in EXT1 and EXT2. All patients had multiple osteochondromas at the long bones, mainly at the tibia, forearm, femur, and humerus. Bowing deformity of the forearms (9/32) and the lower extremities (2/32), and scoliosis (6/32) were observed. The clinical severity was not different between patients with EXT1 or EXT2 variants. One patient with an EXT2 variant and another with an EXT1 microdeletion had the most severe phenotype with class III disease. Four patients with no EXT1 or EXT2 variants had milder phenotypes. Intrafamilial variability in disease severity was not observed. CONCLUSION: We report a hereditary multiple osteochondroma cohort with clinical and molecular data including 12 novel intragenic variants in EXT1 or EXT2, and 4 microdeletions involving EXT1. Taken together, our data expand the existing knowledge of the phenotype-genotype spectrum in hereditary multiple osteochondroma.

An investigation of the etiology and follow-up findings in 35 children with overgrowth syndromes, including biallelic SUZ12 variant.

Overgrowth-intellectual disability (OGID) syndromes are clinically and genetically heterogeneous group of disorders. The aim of this study was to examine the molecular etiology and long-term follow-up findings of Turkish OGID cohort. Thirty-five children with OGID were included in the study. Single gene sequencing, clinical exome analysis, chromosomal microarray analysis and whole exome sequencing were performed. Five pathogenic copy number variants were detected in the patients; three of them located on chromosome 5q35.2 (encompassing NSD1), others on 9q22.3 and 22q13.31. In 19 of 35 patients; we identified pathogenic variants in OGID genes associated with epigenetic regulation, NSD1 (n = 15), HIST1H1E (n = 1), SETD1B (n = 1), and SUZ12 (n = 2). The pathogenic variants in PIK3CA (n = 2), ABCC9 (n = 1), GPC4 (n = 2), FIBP (n = 1), and TMEM94 (n = 1) which had a role in other growth pathways were detected in seven patients. The diagnostic yield was 31/35(88%). Twelve pathogenic variants were novel. The common facial feature of the patients was prominent forehead. The patients with Sotos syndrome were observed to have milder intellectual disability than patients with other OGID syndromes. In conclusion, this study showed, for the first time, that biallelic variants of SUZ12 caused Imagawa-Matsumoto syndrome, monoallelic variants in SETDIB resulted in OGID. Besides expanded the phenotypes of very rare OGID syndromes caused by FIBP and TMEM94.

Investigation of 11p15.5 Methylation Defects Associated with Beckwith-Wiedemann Spectrum and Embryonic Tumor Risk in Lateralized Overgrowth Patients.

The Beckwith-Wiedemann spectrum (BWSp) ranges from isolated lateralized overgrowth (ILO) to classic phenotypes. In this broad clinical spectrum, an epigenetic alteration on chromosome 11p15.5 can be detected. The risk for embryonal tumors is high, especially in patients with lateralized overgrowth (LO). The aim of this study is to investigate epigenetic alterations in 11p15.5 and tumor risk in 87 children with LO. The methylation level of 11p15.5 was examined in the blood of all patients and in skin samples or buccal swabs from 40 patients with negative blood tests; 63.2% of patients were compatible with the ILO phenotype, 18.4% were atypical, and 18.4% were classic. The molecular diagnosis rate was 81.2% for the atypical and classic phenotypes, and 10.9% for the ILO phenotype. In patients with epigenetic alterations, LO was statistically significantly more severe than in test negatives. Tumors developed in six (6.9%) of the total 87 patients with LO; four belonged to the atypical or classical phenotype (12.5%) and two to ILO (3.5%). Three of the four patients with atypical/classical phenotypes had pUPD11, one had IC1-GOM alteration, and two ILO patients were negative. We conclude that LO patients should be monitored for tumor risk even if their epigenetic tests are negative.

A Large Turkish Cohort of Williams Syndrome: The Evaluation of Facial, Cardiovascular, and Neuropsychiatric Features.

OBJECTIVE: Williams syndrome is caused by a microdeletion at 7q11.23 and is characterized by a distinctive face, cardiovascular disease, and intellectual disability with a specific cognitive and behavioral profile. This study aims to evaluate the clinical features and obtain important information that can guide early diagnoses and correct follow-up. MATERIALS AND METHODS: The study included 78 patients whose diagnoses were confirmed by fluorescent in situ hybridization. Facial features, anthropometric measurements, and neurocognitive, endocrine, and urinary system evaluations were obtained from the medical records, and photographs of the patients were evaluated retrospectively. RESULTS: The most common complaints at admission were cardiovascular disease and atypical face. The mean age at admission was 39 ± 4.8 months. The mean age of patients presenting with atypical face was 41 ± 5.6 months, while it was 11 ± 3.1 months in patients presenting with cardiovascular disease. Short nose/bulbous nasal type with anteverted nares and periorbital fullness, which are diagnostic facial features, were present in all patients in the infantile/ early childhood period. 80% of the patients had cardiovascular disease; supravalvular aortic stenosis (53.8%) and peripheral pulmonary artery stenosis (41%) were the most common cardiac anomalies.Intel lectu al/de velop menta l disability was present in 75.6% of the patients. Behavioral disorders including autism spectrum disorder and attention deficit hyperactivity disorder were detected in 50% of our patients. Hypersensitivity to loud and/or sudden sounds was present in all patients. CONCLUSION: We highlighted that recognition of facial findings is important for early diagnosis, especially in patients without cardiovascular disease. The frequency of cardiovascular, endocrinological, renal anomalies, and intellectual disab ility /deve lopme ntal delay was described that provide valuable information in the follow-up of patients.

The Clinical and Molecular Spectrum of Trichorhinophalangeal Syndrome Types I and II in a Turkish Cohort Involving 22 Patients.

OBJECTIVE: Trichorhinophalangeal syndrome is a rare autosomal dominant disorder characterized by distinctive craniofacial and skeletal abnormalities. This study aimed to delineate the trichorhinophalangeal syndrome phenotype and to compare the clinical and molecular findings between trichorhinophalangeal syndrome types I and II. MATERIALS AND METHODS: A total of 22 trichorhinophalangeal syndrome patients aged 0.9-45 years from 17 families were enrolled. Nineteen patients were diagnosed with trichorhin ophalangeal syndrome I and 3 with trichorhinophalangeal syndrome II. Genetic analyses were made by TRPS1 sequencing and/or chromosomal microarray analyses. RESULTS: A novel frameshift variant (c.531_532del), a known missense variant, and whole-gene deletions were the pathogenic TRPS1 variants detected in trichorhinophalangeal syndrome I. Three trichorhinophalangeal syndrome II patients had large deletions with variable breakpoints involving the TRPS1-EXT1 interval. All patients had the typical craniofacial findings of trichorhinophalangeal syndrome such as a pear-shaped nose, long philtrum, and thin upper lip, as well as cone-shaped epiphyses. Sparse hair and eyebrows (20/22), short metacarpals and metatarsals (20/22), and small hands (19/22) were common. While craniofacial and limb abnormalities were similar in trichorhinophalangeal syndrome I and II, 3 of 19 trichorhinophal angeal syndrome I patients had mild, and 2 of 3 trichorhinophalangeal syndrome II patients had severe intellectual disability. Three trichorhinophalangeal syndrome II patients including the patient with the EXT1 deletion beginning from exon 2 had exostoses. In trichorhinophal angeal syndrome II, although microdeletion sizes and facial or skeletal features were not correlated, patients with larger deletions had severe intellectual disability. CONCLUSION: This study has expanded the existing knowledge on the phenotype-genotype spectrum in trichorhinophalangeal syndrome. We suggest including the EXT1 gene partially in the minimal critical region for trichorhinophalangeal syndrome II.

Natural history of clinical features in two brothers with acromesomelic dysplasia related to PRKG2.

Acromesomelic dysplasias (AMD) are a group of skeletal dysplasia characterized by shortening of the middle and distal segments of the limbs. Recently, biallelic PRKG2 variants have been reported to cause a new type of AMD. We detected biallelic novel variant (c.1635-1G > C) in PRKG2 in two brothers with mild to severe short stature, short limbs, cubitus varus, and brachydactyly. Radiological examination showed platyspondyly with anterior beaking of the vertebral bodies, stubby long bones with metaphyseal flaring and moderate brachydactyly with cone-shaped epiphyses of the middle and proximal phalanges. Upper limb proportions of the older brother were clinically classified as rhizomelic, however radiologic findings supported acromesomelia, along with the elbow limitation. Annual follow-ups of the older brother from the age of 5 to 20 years revealed progression of short stature with age but platyspondyly and anterior beaking became less conspicuous. The younger brother showed milder short stature and less conspicuous disproportion of the limbs than those of the older brother; however, platyspondyly and anterior beaking were more prominent on the radiographs obtained at the same age. In conclusion, this report provides new insights into the natural history of AMD type PRKG2 confirming the intrafamilial heterogeneity.

Biallelic frameshift variants in PHLDB1 cause mild-type osteogenesis imperfecta with regressive spondylometaphyseal changes.

BACKGROUND: Osteogenesis imperfecta (OI) is a heterogeneous group of inherited disorders characterised by susceptibility to fractures, primarily due to defects in type 1 collagen. The aim of this study is to present a novel OI phenotype and its causative candidate gene. METHODS: Whole-exome sequencing and clinical evaluation were performed in five patients from two unrelated families. PHLDB1 mRNA expression in blood and fibroblasts was investigated by real-time PCR, and western blot analysis was further performed on skin fibroblasts. RESULTS: The common findings among the five affected children were recurrent fractures and/or osteopaenia, platyspondyly, short and bowed long bones, and widened metaphyses. Metaphyseal and vertebral changes regressed after early childhood, and no fractures occurred under bisphosphonate treatment. We identified biallelic NM_001144758.3:c.2392dup and NM_001144758.3:c.2690_2693del pathogenic variants in PHLDB1 in the affected patients, respectively, in the families; parents were heterozygous for these variants. PHLDB1 encodes pleckstrin homology-like domain family B member-1 (PHLDB1) protein, which has a role in insulin-dependent Akt phosphorylation. Compared with controls, a decrease in the expression levels of PHLDB1 in the blood and skin fibroblast samples was detected. Western blot analysis of cultured fibroblasts further confirmed the loss of PHLDB1. CONCLUSION: Two biallelic frameshift variants in the candidate gene PHLDB1 were identified in independent families with a novel, mild-type, autosomal recessive OI. The demonstration of decreased PHLDB1 mRNA expression levels in blood and fibroblast samples supports the hypothesis that PHLDB1 pathogenic variants are causative for the observed phenotype.

Long-term follow-up findings in a Turkish girl with osteogenesis imperfecta type XX caused by a homozygous MESD variant.

Osteogenesis imperfecta (OI) is a heterogeneous group of disorders with bone fragility. In 2019, homozygous pathogenic variants in MESD were described for the first time in five patients with severe form of OI. To date, 12 patients have been reported. The aim of this study is to report long-term follow-up findings of a girl with MESD variant. She had triangular face, sparse hair, wide fontanelle, blue sclera, softening of the occipital bone, congenital torticollis, and long fingers. Wormian bones, multiple rib and long bone fractures, and platyspondyly were detected in her skeletal radiographs. During the 21-years follow-up, intellectual disability, oligodontia, recurrent fractures, bowing of humerus, hip and knee contractures leading to crossing of the legs, swelling of the interphalangeal joints, and kyphoscoliosis were observed. Although the bisphosphonate treatment was started at 2.5 years of age, recurrent fractures continued to occur until 13 years of age. She lost her walking ability at 4.5 years of age. The final adult height was 128 cm (-6.0 SD). Homozygous c.631_632delAA (p.Lys211Glufs*19) variant in MESD was detected at 19 years of age. In conclusion, this study provides long-term clinical and radiological findings in a patient with a very rare type of OI.

Osteogenesis imperfecta in 140 Turkish families: Molecular spectrum and, comparison of long-term clinical outcome of those with COL1A1/A2 and biallelic variants.

BACKGROUND: Osteogenesis imperfecta (OI) is a clinically and genetically heterogeneous group of diseases characterized by increased bone fragility and deformities. Although most patients with OI have heterozygous mutations in COL1A1 or COL1A2, 17 genes have been reported to cause OI, most of which are autosomal recessive (AR) inherited, during the last years. The aim of this study is to determine the mutation spectrum in Turkish OI cohort and to investigate the genotype-phenotype correlation. METHODS: 150 patients from 140 Turkish families with OI phenotype were included in this study. Mutations in OI-related genes were identified using targeted gene panel, MLPA analysis for COL1A1 and whole exome sequencing. 113 patients who had OI disease-causing variants were followed for 1-20 years. RESULTS: OI disease-causing variants were detected in 117 families, of which 62.4% in COL1A1/A2, 35.9% in AR-related genes. A heterozygous variant in IFITM5 and a hemizygous in MBTPS2 were also described, one in each patient. Eighteen biallelic variants (13 novel) were identified in nine genes (FKBP10, P3H1, SERPINF1, TMEM38B, WNT1, BMP1, CRTAP, FAM46A, MESD) among which FKBP10, P3H1 and SERPINF1 were most common. The most severe phenotypes were in patients with FKBP10, SERPINF1, CRTAP, FAM46A and MESD variants. P3H1 patients had moderate, while BMP1 had the mild phenotype. Clinical phenotypes were variable in patients with WNT1 and TMEM38B mutations. We also found mutations in ten genes (PLS3, LRP5, ANO5, SLC34A1, EFEMP2, PRDM5, GORAB, OCRL1, TNFRSF11B, DPH1) associated with diseases presenting clinical features which overlap OI, in eleven families. CONCLUSION: We identified disease-causing mutations in 83.6% in a large Turkish pediatric OI cohort. 40 novel variants were described. Clinical features and long-term follow-up findings of AR inherited OI types and especially very rare biallelic variants were presented for the first time. Unlike previously reported studies, the mutations that we found in P3H1 were all missense, causing a moderate phenotype.

Specific early signs and long-term follow-up findings of progressive pseudorheumatoid dysplasia (PPRD) in the Turkish cohort.

OBJECTIVES: Progressive pseudorheumatoid dysplasia (PPRD) is a spondyloepiphyseal dysplasia caused by biallelic variants in CCN6. This study aimed to describe the early signs and follow-up findings in 44 Turkish PPRD patients. METHODS: The patients with progressive stiffness of multiple joints, characteristic wide metaphysis of interphalangeal (IP) joints and platyspondyly were clinically diagnosed with PPRD. Fifteen patients who had first symptoms under 3 years of age were grouped as early-onset, while others were grouped as classical. CCN6 sequencing was performed in 43 patients. RESULTS: Thirteen pathogenic/likely pathogenic variants were identified, five were novel. c.156C>A(p.Cys52*) variant was found in 53.3% of the families. The initial symptom in the early-onset group was genu varum deformity, while it was widening of IP joints in the classical group. The median age of onset of symptoms and of diagnosis was 4 and 9.7 years, respectively. The mean follow-up duration was 5.6 years. The median age of onset of IP, elbow, knee and hip stiffness, which became progressive with growth was 5, 9, 9 and 12.2 years, respectively. Waddling gait occurred in 97.7% of the patients. A total of 47.7% lost independent walking ability at the median age of 12 years. In the early-onset group, waddling gait occurred earlier than in classical group (P < 0.001). Two patients had atypical presentation with late-onset and mild or lack of IP involvement. CONCLUSION: We observed that genu varum deformity before the age of 3 years was an early sign for PPRD and almost half of the patients lost walking ability at the median age of 12 years.

Natural history of facial and skeletal features from neonatal period to adulthood in a 3M syndrome cohort with biallelic CUL7 or OBSL1 variants.

3M syndrome is characterized by severe pre- and post-natal growth restriction, typical face, slender tubular bones, tall vertebral bodies, prominent heels and normal intelligence. It is caused by biallelic variants of CUL7, OBSL1 and, more rarely, CCDC8. The aim of this study is to evaluate facial and skeletal findings in 3M patients from neonatal period to adulthood. A total of 19 patients with a median age of diagnosis of 9.2 months were included in this study and were followed for two to 20 years. CUL7 and OBSL1 variants were found in 57.9% and 42.1% of patients, respectively, five of which are novel. Most of patients had triangular face, frontal bossing, short fleshy nose, full fleshy lower lip, transverse groove of rib cage, hyperlordosis and prominent heels. Three new early-diagnostic signs were observed in infants; two were infraorbital swelling of the lower lid and facial infantile hemangioma, both of which became less pronounced with aging. The third was the central tubercle of the upper lip that became more prominent with in time. While slender long bones did not change with aging, the tall vertebral bodies became more prominent radiologically. The mean birth length in patients was -4.3 SDS. Eight patients reached a mean final height of -4.9 SDS. Despite described growth hormone (GH) insensitivity in 3M syndrome, 12 patients either with GH deficiency or with normal GH levels were treated with GH; seven patients responded with an increase in height SDS. This study not only provided early diagnostic signs of the syndrome, but also presented important follow-up findings.

Expanding the clinical phenotype of RASopathies in 38 Turkish patients, including the rare LZTR1, RAF1, RIT1 variants, and large deletion in NF1.

RASopathies are a group of disorders caused by pathogenic variants in the genes encoding Ras/mitogen-activated protein kinase pathway and share overlapping clinical and molecular features. This study is aimed to describe the clinical and molecular features of 38 patients with RASopathies. Sanger or targeted next-generation sequencing of related genes and multiplex ligation-dependent-probe amplification analysis for NF1 were performed. The pathogenic variant detection rate was 94.4%. While PTPN11 was responsible for 50% of 18 patients with Noonan syndrome (NS), SOS1, LZTR1, RIT1, and RAF1 were responsible for the remaining 27.8%, 11.1%, 5.5%, and 5.5%, respectively. Three variants in LZTR1 were novel, of which two were identified in the compound heterozygous state in a patient with intellectual disability and hypertrophic cardiomyopathy, whereas the third variant was found in the heterozygous state in a patient with pulmonary stenosis and normal intelligence. We described pyloric stenosis, knee dislocation, and cleft palate in patients with SOS1, RIT1, and RAF1 variants, respectively, that was not previously reported. We detected a PTPN11 variant in three patients from same family with NS with multiple lentigines. BRAF and MAP2K2 variants were found in eight patients with Cardiofaciocutaneous syndrome. Two variants in HRAS were detected in two Costello syndrome patients, one with a mild and the other with a severe phenotype. While large NF1 deletions were identified in four Neurofibromatosis-NS patients with intellectual disability, intelligence was normal in one patient with missense variant. In conclusion, this study provided three novel variants in LZTR1 and expanded the clinical phenotype of rare RASopathies.

Long-Term Follow-Up Outcomes of 19 Patients with Osteogenesis Imperfecta Type XI and Bruck Syndrome Type I Caused by FKBP10 Variants.

Osteogenesis imperfecta type XI (OI-XI) and Bruck syndrome type I (BS1) are two rare disorders caused by biallelic variants in the FKBP10, characterized by early-onset bone fractures and progressive skeletal deformities. The patients with OI-XI, also co-segregated with autosomal-recessive epidermolysis bullosa simplex caused by KRT14 variant, have been reported. In this study, the follow-up clinical features of the patients with OI-XI and BS1 phenotypes due to biallelic FKBP10 variants are compared. The aim of this study is to investigate the follow-up findings of OI-XI and BS1 phenotypes in patients with the FKBP10 variants. A total of 19 children, ten males and nine females, from 16 unrelated families were included in the study. FKBP10 variants were investigated by next-generation sequencing (NGS) based panel gene test or Sanger sequencing. Seventeen patients were followed between 1.5 and 16.8 years, and the last follow-up age was between 2 and 24.6 years (median 10.7 years). They received intravenous bisphosphonate infusions once every 3 months in follow-up period. We identified four different biallelic FKBP10 variants, two of which are novel (c.890_897dup TGATGGAC, p.Gly300Ter and c.1256 + 1G > A) in 16 families. Five of these patients also had findings of epidermolysis bullosa simplex, and the same biallelic c.612T > A (p.Tyr204Ter) variant in KRT14, as well as FKBP10, were identified. Twelve patients were diagnosed with OI-XI; whereas, seven were diagnosed with BS1. The BS1 phenotype was late-onset and the annual fracture number was lower. After bisphosphonate treatment, bone mineral densitometry Z score at L1-L4 increased (p = 0.005) and the number of annual fractures decreased (p = 0.036) in patients with OI-XI. However, no significant effect of bisphosphonate treatment was found on these values in BS1 patients. Despite the treatment, the rate of scoliosis and long bone deformity had increased in both groups at the last examination; and, only two patients could take a few steps with the aid of a walker, while others were not ambulatory, and they used wheelchairs for mobility. We identified two novel variants in FKBP10. Families originating from the same geographic region and having the same variant suggest founder effects. Although the number of fractures decreased with bisphosphonate treatment, none of our patients were able to walk during the follow-up. This study is valuable in terms of showing the follow-up findings of patients with FKBP10 variants for the first time.

Skeletal and molecular findings in 51 Cleidocranial dysplasia patients from Turkey.

Loss or decrease of function in runt-related transcription factor 2 encoded by RUNX2 is known to cause a rare autosomal-dominant skeletal disorder, cleidocranial dysplasia (CCD). Clinical spectrum and genetic findings in 51 CCD patients from 30 unrelated families are herein presented. In a majority of the patients, facial abnormalities, such as delayed fontanel closure (89%), parietal and frontal bossing (80%), metopic groove (77%), midface hypoplasia (94%), and abnormal mobility of shoulders (90%), were recorded following clinical examination. In approximately one-half of the subjects, wormian bone (51%), short stature (43%), bell-shaped thorax (42%), wide pubic symphysis (50%), hypoplastic iliac wing (59%), and chef's hat sign (44%) presented in available radiological examinations. Scoliosis was identified in 28% of the patients. Investigation of RUNX2 revealed small sequence alterations in 90% and gross deletions in 10% of the patients; collectively, 23 variants including 11 novel changes (c.29_30insT, c.203delAinsCG, c.423 + 2delT, c.443_454delTACCAGATGGGAinsG, c.505C > T, c.594_595delCTinsG, c.636_637insC, c.685 + 5G > A, c.1088G > T, c.1281delC, Exon 6-9 deletion) presented high allelic heterogeneity. Novel c.29_30insT is unique in affecting the P1-driven long isoform of RUNX2, which is expected to disrupt the N-terminal region of RUNX2; this was shown in two unrelated phenotypically discordant patients. The clinical findings highlighted mild intra-familial genotype-phenotype correlation in our CCD cohort.

Resolution of sclerotic lesions of dysosteosclerosis due to biallelic SLC29A3 variant in a Turkish girl.

Dysosteosclerosis is a group of sclerosing bone dysplasia characterized by short stature, increased bone fragility, osteosclerosis, and platyspondyly. It is a genetically heterogeneous disorder caused by biallelic mutations in the SLC29A3, TNFRSF11A, TCIRG1, and CSF1R genes. To date, four dysosteosclerosis patients with SLC29A3 mutations have been reported. Here, we report biallelic SLC29A3 (c.303_320dupCTACTTTGAGAGCTACCT) variant in a three-year-old girl. She had large anterior fontanelle, fracture history, short stature, camptodactyly, elbow contracture, and melanocytic nevus. Initial skeletal radiographs revealed platyspondyly, dense vertebral endplates (sandwich appearance of the vertebral bodies), diffuse sclerosis of the peripheral side of the pelvic bones, sclerosis of metaphysis and diaphysis of the long bones, metaphyseal widening, and diaphyseal cortical thickening. Mild sclerosis was also present in the skull base, maxilla, rib, scapula, and phalanges. Notably, we observed that sandwich vertebrae appearance significantly resolved and sclerosis of ribs, scapula, pelvis, and long bone metaphysis regressed over a 2.5-year period. However, platyspondyly, metaphyseal widening, and diaphyseal cortical thickening persisted. In conclusion, this study demonstrates spontaneous resolution of osteosclerosis, which was not described previously in patients with dysosteosclerosis.