Clinical and neurogenetic characterisation of autosomal recessive RBL2-associated progressive neurodevelopmental disorder.

Retinoblastoma (RB) proteins are highly conserved transcriptional regulators that play important roles during development by regulating cell-cycle gene expression. RBL2 dysfunction has been linked to a severe neurodevelopmental disorder. However, to date, clinical features have only been described in six individuals carrying five biallelic predicted loss of function (pLOF) variants. To define the phenotypic effects of RBL2 mutations in detail, we identified and clinically characterized a cohort of 28 patients from 18 families carrying LOF variants in RBL2 , including fourteen new variants that substantially broaden the molecular spectrum. The clinical presentation of affected individuals is characterized by a range of neurological and developmental abnormalities. Global developmental delay and intellectual disability were uniformly observed, ranging from moderate to profound and involving lack of acquisition of key motor and speech milestones in most patients. Frequent features included postnatal microcephaly, infantile hypotonia, aggressive behaviour, stereotypic movements and non-specific dysmorphic features. Common neuroimaging features were cerebral atrophy, white matter volume loss, corpus callosum hypoplasia and cerebellar atrophy. In parallel, we used the fruit fly, Drosophila melanogaster , to investigate how disruption of the conserved RBL2 orthologueue Rbf impacts nervous system function and development. We found that Drosophila Rbf LOF mutants recapitulate several features of patients harboring RBL2 variants, including alterations in the head and brain morphology reminiscent of microcephaly, and perturbed locomotor behaviour. Surprisingly, in addition to its known role in controlling tissue growth during development, we find that continued Rbf expression is also required in fully differentiated post-mitotic neurons for normal locomotion in Drosophila , and that adult-stage neuronal re-expression of Rbf is sufficient to rescue Rbf mutant locomotor defects. Taken together, this study provides a clinical and experimental basis to understand genotype-phenotype correlations in an RBL2 -linked neurodevelopmental disorder and suggests that restoring RBL2 expression through gene therapy approaches may ameliorate aspects of RBL2 LOF patient symptoms.

Variant characterisation and clinical profile in a large cohort of patients with Ellis-van Creveld syndrome and a family with Weyers acrofacial dysostosis.

BACKGROUND: Ellis-van Creveld syndrome (EvC) is a recessive disorder characterised by acromesomelic limb shortening, postaxial polydactyly, nail-teeth dysplasia and congenital cardiac defects, primarily caused by pathogenic variants in EVC or EVC2. Weyers acrofacial dysostosis (WAD) is an ultra-rare dominant condition allelic to EvC. The present work aimed to enhance current knowledge on the clinical manifestations of EvC and WAD and broaden their mutational spectrum. METHODS: We conducted molecular studies in 46 individuals from 43 unrelated families with a preliminary clinical diagnosis of EvC and 3 affected individuals from a family with WAD and retrospectively analysed clinical data. The deleterious effect of selected variants of uncertain significance was evaluated by cellular assays. MAIN RESULTS: We identified pathogenic variants in EVC/EVC2 in affected individuals from 41 of the 43 families with EvC. Patients from each of the two remaining families were found with a homozygous splicing variant in WDR35 and a de novo heterozygous frameshift variant in GLI3, respectively. The phenotype of these patients showed a remarkable overlap with EvC. A novel EVC2 C-terminal truncating variant was identified in the family with WAD. Deep phenotyping of the cohort recapitulated 'classical EvC findings' in the literature and highlighted findings previously undescribed or rarely described as part of EvC. CONCLUSIONS: This study presents the largest cohort of living patients with EvC to date, contributing to better understanding of the full clinical spectrum of EvC. We also provide comprehensive information on the EVC/EVC2 mutational landscape and add GLI3 to the list of genes associated with EvC-like phenotypes.

Diagnosis and management in Rubinstein-Taybi syndrome: first international consensus statement.

Rubinstein-Taybi syndrome (RTS) is an archetypical genetic syndrome that is characterised by intellectual disability, well-defined facial features, distal limb anomalies and atypical growth, among numerous other signs and symptoms. It is caused by variants in either of two genes (CREBBP, EP300) which encode for the proteins CBP and p300, which both have a function in transcription regulation and histone acetylation. As a group of international experts and national support groups dedicated to the syndrome, we realised that marked heterogeneity currently exists in clinical and molecular diagnostic approaches and care practices in various parts of the world. Here, we outline a series of recommendations that document the consensus of a group of international experts on clinical diagnostic criteria for types of RTS (RTS1: CREBBP; RTS2: EP300), molecular investigations, long-term management of various particular physical and behavioural issues and care planning. The recommendations as presented here will need to be evaluated for improvements to allow for continued optimisation of diagnostics and care.

DISP1 deficiency: Monoallelic and biallelic variants cause a spectrum of midline craniofacial malformations.

PURPOSE: DISP1 encodes a transmembrane protein that regulates the secretion of the morphogen, Sonic hedgehog, a deficiency of which is a major cause of holoprosencephaly (HPE). This disorder covers a spectrum of brain and midline craniofacial malformations. The objective of the present study was to better delineate the clinical phenotypes associated with division transporter dispatched-1 (DISP1) variants. METHODS: This study was based on the identification of at least 1 pathogenic variant of the DISP1 gene in individuals for whom detailed clinical data were available. RESULTS: A total of 23 DISP1 variants were identified in heterozygous, compound heterozygous or homozygous states in 25 individuals with midline craniofacial defects. Most cases were minor forms of HPE, with craniofacial features such as orofacial cleft, solitary median maxillary central incisor, and congenital nasal pyriform aperture stenosis. These individuals had either monoallelic loss-of-function variants or biallelic missense variants in DISP1. In individuals with severe HPE, the DISP1 variants were commonly found associated with a variant in another HPE-linked gene (ie, oligogenic inheritance). CONCLUSION: The genetic findings we have acquired demonstrate a significant involvement of DISP1 variants in the phenotypic spectrum of midline defects. This underlines its importance as a crucial element in the efficient secretion of Sonic hedgehog. We also demonstrated that the very rare solitary median maxillary central incisor and congenital nasal pyriform aperture stenosis combination is part of the DISP1-related phenotype. The present study highlights the clinical risks to be flagged up during genetic counseling after the discovery of a pathogenic DISP1 variant.

Association of Antenatal Evaluations with Postmortem and Genetic Findings in the Series of Fetal Osteogenesis Imperfecta.

INTRODUCTION: Counseling osteogenesis imperfecta (OI) pregnancies is challenging due to the wide range of onsets and clinical severities, from perinatal lethality to milder forms detected later in life. METHODS: Thirty-eight individuals from 36 families were diagnosed with OI through prenatal ultrasonography and/or postmortem clinical and radiographic findings. Genetic analysis was conducted on 26 genes associated with OI in these subjects that emerged over the past 20 years; while some genes were examined progressively, all 26 genes were examined in the group where no pathogenic variations were detected. RESULTS: Prenatal and postnatal observations both consistently showed short limbs in 97%, followed by bowing of the long bones in 89%. Among 32 evaluated cases, all exhibited cranial hypomineralization. Fractures were found in 29 (76%) cases, with multiple bones involved in 18 of them. Genetic associations were disclosed in 27 families with 22 (81%) autosomal dominant and five (19%) autosomal recessive forms, revealing 25 variants in six genes (COL1A1, COL1A2, CREB3L1, P3H1, FKBP10, and IFITM5), including nine novels. Postmortem radiological examination showed variability in intrafamily expression of CREBL3- and P3H1-related OI. CONCLUSION: Prenatal diagnosis for distinguishing OI and its subtypes relies on factors such as family history, timing, ultrasound, genetics, and postmortem evaluation.

Prenatal Diagnosis of Crossed Pulmonary Arteries with a Postnatal Diagnosis of CHARGE Syndrome.

Introduction: Crossed pulmonary arteries (CPA) is an abnormality in which the ostium of the left pulmonary artery is located rightward and the ostium of the right pulmonary artery is leftward. Case report: We diagnosed a fetus with CPA prenatally. In fetal echocardiography, left pulmonary artery was seen to pass beneath the ductus and directing toward the left side and pulmonary artery bifurcation could not be demonstrated at the same plane. Postnatal echocardiography reconfirmed the presence of CPA. Bilateral choanal atresia, genital hypoplasia, hearing loss with facial and external ear asymmetry and psychomotor delay of the newborn led to clinical diagnosis of CHARGE syndrome and was confirmed by gene analysis. Discussion/Conclusion: CPA may be one of the cardiac anomalies in CHARGE syndrome.

Clinical and molecular characteristics of 26 fetuses with lethal multiple congenital contractures.

Multiple congenital contractures (MCC) due to fetal akinesia manifest across a broad spectrum of diseases, ranging from mild distal arthrogryposis to lethal fetal akinesia deformation sequence. We hereby present a series of 26 fetuses displaying severe MCC phenotypes from 18 families and describe detailed prenatal ultrasound findings, postmortem clinical evaluations, and genetic investigations. Most common prenatal findings were abnormal facial profile (65%), central nervous system abnormalities (62%), polyhydramnios (50%), increased nuchal translucency (50%), and fetal hydrops (35%). Postmortem examinations unveiled additional anomalies including facial dysmorphisms, dysplastic skeletal changes, ichthyosis, multiple pterygia, and myopathy, allowing preliminary diagnosis of particular Mendelian disorders in multiple patients. Evaluation of the parents revealed maternal grip myotonia in one family. By exome sequencing and targeted testing, we identified causative variants in ACTC1, CHST14, COG6, DMPK, DOK7, HSPG2, KLHL7, KLHL40, KIAA1109, NEB, PSAT1, RAPSN, USP14, and WASHC5 in 15 families, and one patient with a plausible diagnosis associated with biallelic NEB variants. Three patients received a dual diagnosis. Pathogenic alterations in newly discovered genes or in previously known genes recently linked to new MCC phenotypes were observed in 44% of the cohort. Our results provide new insights into the clinical and molecular landscape of lethal MCC phenotypes.

Trichothiodystrophy-associated MPLKIP maintains DBR1 levels for proper lariat debranching and ectodermal differentiation.

The brittle hair syndrome Trichothiodystrophy (TTD) is characterized by variable clinical features, including photosensitivity, ichthyosis, growth retardation, microcephaly, intellectual disability, hypogonadism, and anaemia. TTD-associated mutations typically cause unstable mutant proteins involved in various steps of gene expression, severely reducing steady-state mutant protein levels. However, to date, no such link to instability of gene-expression factors for TTD-associated mutations in MPLKIP/TTDN1 has been established. Here, we present seven additional TTD individuals with MPLKIP mutations from five consanguineous families, with a newly identified MPLKIP variant in one family. By mass spectrometry-based interaction proteomics, we demonstrate that MPLKIP interacts with core splicing factors and the lariat debranching protein DBR1. MPLKIP-deficient primary fibroblasts have reduced steady-state DBR1 protein levels. Using Human Skin Equivalents (HSEs), we observed impaired keratinocyte differentiation associated with compromised splicing and eventually, an imbalanced proteome affecting skin development and, interestingly, also the immune system. Our data show that MPLKIP, through its DBR1 stabilizing role, is implicated in mRNA splicing, which is of particular importance in highly differentiated tissue.

Nance-Horan Syndrome: characterization of dental, clinical and molecular features in three new families.

BACKGROUND: Nance-Horan syndrome (NHS; MIM 302,350) is an extremely rare X-linked dominant disease characterized by ocular and dental anomalies, intellectual disability, and facial dysmorphic features. CASE PRESENTATION: We report on five affected males and three carrier females from three unrelated NHS families. In Family 1, index (P1) showing bilateral cataracts, iris heterochromia, microcornea, mild intellectual disability, and dental findings including Hutchinson incisors, supernumerary teeth, bud-shaped molars received clinical diagnosis of NHS and targeted NHS gene sequencing revealed a novel pathogenic variant, c.2416 C > T; p.(Gln806*). In Family 2, index (P2) presenting with global developmental delay, microphthalmia, cataracts, and ventricular septal defect underwent SNP array testing and a novel deletion encompassing 22 genes including the NHS gene was detected. In Family 3, two half-brothers (P3 and P4) and maternal uncle (P5) had congenital cataracts and mild to moderate intellectual deficiency. P3 also had autistic and psychobehavioral features. Dental findings included notched incisors, bud-shaped permanent molars, and supernumerary molars. Duo-WES analysis on half-brothers showed a hemizygous novel deletion, c.1867delC; p.(Gln623ArgfsTer26). CONCLUSIONS: Dental professionals can be the first-line specialists involved in the diagnosis of NHS due to its distinct dental findings. Our findings broaden the spectrum of genetic etiopathogenesis associated with NHS and aim to raise awareness among dental professionals.

RAF1 deficiency causes a lethal syndrome that underscores RTK signaling during embryogenesis.

Somatic and germline gain-of-function point mutations in RAF, one of the first oncogenes to be discovered in humans, delineate a group of tumor-prone syndromes known as the RASopathies. In this study, we document the first human phenotype resulting from the germline loss-of-function of the proto-oncogene RAF1 (a.k.a. CRAF). In a consanguineous family, we uncovered a homozygous p.Thr543Met variant segregating with a neonatal lethal syndrome with cutaneous, craniofacial, cardiac, and limb anomalies. Structure-based prediction and functional tests using human knock-in cells showed that threonine 543 is essential to: (i) ensure RAF1's stability and phosphorylation, (ii) maintain its kinase activity toward substrates of the MAPK pathway, and (iii) protect from stress-induced apoptosis mediated by ASK1. In Xenopus embryos, mutant RAF1T543M failed to phenocopy the effects of normal and overactive FGF/MAPK signaling, confirming its hypomorphic activity. Collectively, our data disclose the genetic and molecular etiology of a novel lethal syndrome with progeroid features, highlighting the importance of RTK signaling for human development and homeostasis.

Revisiting TOP2B-related phenotypes: Three new cases and literature review.

DNA Topoisomerase IIß (TOP2B) acts on DNA topology during transcription and has a critical role in neural development. Heterozygous pathogenic changes in its encoding gene, TOP2B (MIM *126431), has been linked with three overlapping phenotypes characterized by immunodeficiency, acral and urogenital anomalies: Hoffman, BILU and Ablepharon-macrostomia-like syndrome. We herein report on a mother and two sons with distinct TOP2B-phenotype. Two males reported further delineated genital phenotype of males and all reported patients were reviewed for genotype-phenotype correlation. We believe the patients reported herein along with the previously defined 11 represent a phenotypic spectrum from mild-to-severe immunological, acral and urogenital involvement, for which we propose the acronym "TOP2B-related Immunodeficiency and Congenital Anomalies Spectrum (TICAS)".

Clinical features of generalized lipodystrophy in Turkey: A cohort analysis.

AIM: To describe the Turkish generalized lipodystrophy (GL) cohort with the frequency of each complication and the death rate during the period of the follow-up. METHODS: This study reports on 72 patients with GL (47 families) registered at different centres in Turkey that cover all regions of the country. The mean ± SD follow-up was 86 ± 78 months. RESULTS: The Kaplan-Meier estimate of the median time to diagnosis of diabetes and/or prediabetes was 16 years. Hyperglycaemia was not controlled in 37 of 45 patients (82.2%) with diabetes. Hypertriglyceridaemia developed in 65 patients (90.3%). The Kaplan-Meier estimate of the median time to diagnosis of hypertriglyceridaemia was 14 years. Hypertriglyceridaemia was severe (≥ 500 mg/dl) in 38 patients (52.8%). Seven (9.7%) patients suffered from pancreatitis. The Kaplan-Meier estimate of the median time to diagnosis of hepatic steatosis was 15 years. Liver disease progressed to cirrhosis in nine patients (12.5%). Liver disease was more severe in congenital lipodystrophy type 2 (CGL2). Proteinuric chronic kidney disease (CKD) developed in 32 patients (44.4%) and cardiac disease in 23 patients (31.9%). Kaplan-Meier estimates of the median time to diagnosis of CKD and cardiac disease were 25 and 45 years, respectively. Females appeared to have a more severe metabolic disease, with an earlier onset of metabolic abnormalities. Ten patients died during the follow-up period. Causes of death were end-stage renal disease, sepsis (because of recurrent intestinal perforations, coronavirus disease, diabetic foot infection and following coronary artery bypass graft surgery), myocardial infarction, heart failure because of dilated cardiomyopathy, stroke, liver complications and angiosarcoma. CONCLUSIONS: Standard treatment approaches have only a limited impact and do not prevent the development of severe metabolic abnormalities and early onset of organ complications in GL.

Clinical and genetic spectrum from a prototype of ciliopathy: Joubert syndrome.

OBJECTIVE: Joubert syndrome is a neurodevelopmental disorder with a distinctive hindbrain malformation called molar tooth sign, causing motor and cognitive impairments. More than 40 genes have been associated with Joubert syndrome. We aim to describe a group of Joubert syndrome patients clinically and genetically emphasizing organ involvement. METHODS: We retrospectively collected clinical information and molecular diagnosis data of 22 patients with Joubert syndrome from multiple facilities. Clinical exome or whole-exome sequencing were performed to identify causal variations in genes. RESULTS: The most common variants were in the CPLANE1, CEP290, and TMEM67 genes, and other causative genes were AHI1, ARMC9, CEP41, CSPP1, HYLS1, KATNIP, KIAA0586, KIF7, RPGRIP1L, including some previously unreported variants in these genes. Multi-systemic organ involvement was observed in nine (40%) patients, with the eye being the most common, including Leber's congenital amaurosis, ptosis, and optic nerve coloboma. Portal hypertension and esophageal varices as liver and polycystic kidney disease and nephronophthisis as kidney involvement was encountered in our patients. The HYLS1 gene, which commonly causes hydrolethalus syndrome 1, was also associated with Joubert syndrome in one of our patients. A mild phenotype with hypophyseal hormone deficiencies without the classical molar tooth sign was observed with compound heterozygous and likely pathogenic variants not reported before in the KATNIP gene. CONCLUSION: Some rare variants that display prominent genetic heterogeneity with variable severity are first reported in our patients. In our study of 22 Joubert syndrome patients, CPLANE1 is the most affected gene, and Joubert syndrome as a ciliopathy is possible without a classical molar tooth sign, like in the KATNIP gene-affected patients.

Fetal skeletal dysplasia cohort of a single tertiary referral center in Istanbul, Turkey.

We report on 314 fetal cases from 297 unrelated families with skeletal dysplasia evaluated in the postmortem period from 2000 to 2017 at a single clinical genetics center in Istanbul, Turkey. The definite diagnostic yield was 40% during the prenatal period, while it reached 74.5% when combined with postmortem clinical and radiological evaluation. Molecular analyses were performed in 25.5% (n: 76) of families, and 21 novel variants were identified. Classification according to International Skeletal Dysplasia Society-2019 revision revealed limb hypoplasia-reduction defects group (39) as the leading one, 24.5%, then followed by FGFR3 chondrodysplasias, osteogenesis imperfecta, and decreased mineralization and polydactyly-syndactyly-triphalangism groups 13.6, 11.1, and 8.9%, respectively. The inheritance pattern was autosomal recessive in 54% and autosomal dominant in 42.6% of index cases. The overall consanguinity rate of the cohort was 33%. The high prevalence of ultrarare diseases along with two or more unrelated autosomal recessive entities running in the same family was noteworthy. This study highlights the pivotal role of postmortem evaluation by an experienced clinical geneticist to achieve a high diagnostic yield in fetal skeletal dysplasia cohorts. The cohort is not only a representation of the spectrum of skeletal dysplasias in a population with a high consanguinity rate but also provides an ideal research group to work on to identify the unknowns of early fetal life.

DPP9 deficiency: An inflammasomopathy that can be rescued by lowering NLRP1/IL-1 signaling.

Dipeptidyl peptidase 9 (DPP9) is a direct inhibitor of NLRP1, but how it affects inflammasome regulation in vivo is not yet established. Here, we report three families with immune-associated defects, poor growth, pancytopenia, and skin pigmentation abnormalities that segregate with biallelic DPP9 rare variants. Using patient-derived primary cells and biochemical assays, these variants were shown to behave as hypomorphic or knockout alleles that failed to repress NLRP1. The removal of a single copy of Nlrp1a/b/c, Asc, Gsdmd, or Il-1r, but not Il-18, was sufficient to rescue the lethality of Dpp9 mutant neonates in mice. Similarly, dpp9 deficiency was partially rescued by the inactivation of asc, an obligate downstream adapter of the NLRP1 inflammasome, in zebrafish. These experiments suggest that the deleterious consequences of DPP9 deficiency were mostly driven by the aberrant activation of the canonical NLRP1 inflammasome and IL-1ß signaling. Collectively, our results delineate a Mendelian disorder of DPP9 deficiency driven by increased NLRP1 activity as demonstrated in patient cells and in two animal models of the disease.

Prenatal ultrasonographic features in Blomstrand osteochondrodysplasia: Antenatal case series confirmed by postmortem radiology and molecular diagnosis.

OBJECTIVE: Blomstrand osteochondrodysplasia (BOCD, MIM #215045) is an ultrarare lethal skeletal dysplasia (LSD) perinatally, characterized by extremely advanced bone maturation, generalized osteosclerosis, and severe tetramicromelia caused by biallelic loss-of-function mutations in the parathyroid hormone receptor-1 gene (PTHR1). We aim to describe prenatal ultrasonographic features in a retrospective fetal case series of BOCD and emphasize the importance of multidisciplinary antenatal evaluation of LSDs to improve the differential diagnosis. METHOD: Prenatal ultrasound findings of five fetal cases diagnosed with BOCD between 2000 and 2019 in the Prenatal Diagnosis Unit and Medical Genetics were reviewed, along with postmortem examination results and confirmatory molecular results. RESULTS: All fetuses presented with severe sonographic findings of LSDs comprising tetramicromelia, thoracic hypoplasia, and retro-micrognathia. Marked cervical hyperextension was present in three fetuses. Flared metaphyses were prenatally identified in only one fetus. X-rays of four fetuses evaluated postmortem showed advanced bone maturation, generalized osteosclerosis, and dumbbell-like appearance of long bones due to metaphyseal enlargement. CONCLUSION: The presence of retro-micrognathia along with a protruding tongue and severe metaphyseal flaring can suggest a diagnosis of BOCD, when prenatal ultrasound findings are indicative for LSD. The diagnosis can be ascertained through postmortem clinical and radiological evaluation and/or molecular testing.

Loss of FOCAD, operating via the SKI messenger RNA surveillance pathway, causes a pediatric syndrome with liver cirrhosis.

Cirrhosis is usually a late-onset and life-threatening disease characterized by fibrotic scarring and inflammation that disrupts liver architecture and function. While it is typically the result of alcoholism or hepatitis viral infection in adults, its etiology in infants is much less understood. In this study, we report 14 children from ten unrelated families presenting with a syndromic form of pediatric liver cirrhosis. By genome/exome sequencing, we found recessive variants in FOCAD segregating with the disease. Zebrafish lacking focad phenocopied the human disease, revealing a signature of altered messenger RNA (mRNA) degradation processes in the liver. Using patient's primary cells and CRISPR-Cas9-mediated inactivation in human hepatic cell lines, we found that FOCAD deficiency compromises the SKI mRNA surveillance pathway by reducing the levels of the RNA helicase SKIC2 and its cofactor SKIC3. FOCAD knockout hepatocytes exhibited lowered albumin expression and signs of persistent injury accompanied by CCL2 overproduction. Our results reveal the importance of FOCAD in maintaining liver homeostasis and disclose a possible therapeutic intervention point via inhibition of the CCL2/CCR2 signaling axis.

A New Family with a Novel OTUD6B Mutation: Practicing Whole Exome Sequencing for Antenatal Diagnosis of Tetralogy of Fallot.

OTUD6B, which encodes a member of the ovarian tumor domain-containing deubiquitinating enzyme, has recently been associated with autosomal recessive intellectual disability syndrome with seizures and dysmorphic features. Here, we report one additional case with Tetralogy of Fallot (ToF), who has microcephaly and dysmorphic features along with renal parenchymal disease with simple cortical cysts. The family's first pregnancy was medically terminated due to antenatal diagnosis of ToF. A novel homozygous variant in OTUD6B (c.815T>G; p.[Ile272Arg]) was revealed by whole exome sequencing (WES) along with a previously reported heterozygous PKD1 variant, unraveling the blended phenotype observed in the proband. Our findings highlight the importance of WES for the prenatal diagnosis of ToF and expand the OTUD6B mutational spectrum.

Clinical and molecular genetic findings of Crisponi/cold-induced sweating syndrome (CS/CISS) spectrum in patients from Turkey.

Crisponi/cold-induced sweating syndrome (CS/CISS) is a rare autosomal recessive disorder characterized by episodic hyperthermia, arthrogryposis, impaired feeding ability, and respiratory distress. The classic CS/CISS is mainly associated with CRLF1 and, rarely, CLCF1. PERCHING syndrome, previously known as CS/CISS type-3 associated with biallelic pathogenic variants in KLHL7, is notable for its few overlapping manifestations. This study presents genotype-phenotype relationships in CS/CISS-like spectrum associated with CRLF1 and KLHL7. Clinical findings of 19 patients from 14 families and four patients from three families were found in association with six different CRLF1 and three different KLHL7 variants, respectively. c.167T>C and c.713delC of the CRLF1 gene and the c.642G>C of the KLHL7 were novel. The c.708_709delCCinsT allele of CRLF1 was identified in 10 families from the Mardin province of Turkey, underlining that an ancestral haplotype has become widespread. CRLF1-associated phenotypes revealed novel manifestations such as prenatal oligohydramnios, benign external hydrocephalus, previously unreported dysmorphic features emerging with advancing age, severe palmoplantar keratoderma and facial erythema, hypopigmented macules and streaks, and recurrent cardiac arrests. KLHL7 variants presented with glabellar nevus flammeus, blepharophimosis, microcephaly, thin corpus callosum, and cleft palate. Abnormalities of sweating, observed in one patient reported herein, is known to be very rare among KLHL7-related phenotypes.

Evaluation of growth, puberty, osteoporosis, and the response to long-term bisphosphonate therapy in four patients with osteoporosis-pseudoglioma syndrome.

Osteoporosis-pseudoglioma syndrome (OPPG; MIM #259770) is a rare autosomal recessively inherited disease, characterized by early-onset osteoporosis and congenital blindness, caused by loss-of-function mutations in the LRP5 gene. Beneficial effects of bisphosphonate treatment in patients with OPPG are well known, while follow-up data on growth and pubertal parameters are limited. This article provides clinical follow-up data and long-term bisphosphonate treatment results in four OPPG patients from three unrelated families, ranging between 2.5 and 7 years of age at presentation. Clinical diagnosis was molecularly confirmed in all patients, with four different germline biallelic LRP5 mutations including a novel nonsense variant c.3517C>T (p.(Gln1173*)) in two siblings with marked phenotypic variability. Anthropometric and pubertal data and bone mineral density (BMD) measurements were evaluated retrospectively. Early puberty was observed in two patients. The bisphosphonate treatment duration of patients varied around 4-7 years and improvement in BMD z-scores with bisphosphonate treatment was demonstrated in all patients (z-score changes were +5.6, +4.0, +1.0, and +1.3). Although further research is needed to identify the possible association between early puberty and OPPG, all OPPG patients should be followed up with detailed endocrinological evaluation regarding pubertal status.