Monodactyly in a patient with CHARGE syndrome: An additional case report.

CHARGE syndrome is a rare autosomal dominant syndrome characterized by multiple congenital anomalies including coloboma, heart defects, ear anomalies, and developmental delay, caused by pathogenic variants in the CHD7 gene. The discovery of the molecular basis of this syndrome increased the number of cases reported and expanded the phenotype and clinical variability. Limb anomalies are occasional clinical findings in this syndrome, present in about 30% of reported cases. The occurrence of limb anomalies in this syndrome suggests that it should be considered as part of the phenotypic spectrum. Here, we describe an individual with CHARGE syndrome presenting unilateral monodactyly.

Al-Gazali Skeletal Dysplasia Constitutes the Lethal End of ADAMTSL2-Related Disorders.

Lethal short-limb skeletal dysplasia Al-Gazali type (OMIM %601356), also called dysplastic cortical hyperostosis, Al-Gazali type, is an ultra-rare disorder previously reported in only three unrelated individuals. The genetic etiology for Al-Gazali skeletal dysplasia has up until now been unknown. Through international collaborative efforts involving seven clinical centers worldwide, a cohort of nine patients with clinical and radiographic features consistent with short-limb skeletal dysplasia Al-Gazali type was collected. The affected individuals presented with moderate intrauterine growth restriction, relative macrocephaly, hypertrichosis, large anterior fontanelle, short neck, short and stiff limbs with small hands and feet, severe brachydactyly, and generalized bone sclerosis with mild platyspondyly. Biallelic disease-causing variants in ADAMTSL2 were detected using massively parallel sequencing (MPS) and Sanger sequencing techniques. Six individuals were compound heterozygous and one individual was homozygous for pathogenic variants in ADAMTSL2. In one of the families, pathogenic variants were detected in parental samples only. Overall, this study sheds light on the genetic cause of Al-Gazali skeletal dysplasia and identifies it as a semi-lethal part of the spectrum of ADAMTSL2-related disorders. Furthermore, we highlight the importance of meticulous analysis of the pseudogene region of ADAMTSL2 where disease-causing variants might be located. © 2023 The Authors. Journal of Bone and Mineral Research published by Wiley Periodicals LLC on behalf of American Society for Bone and Mineral Research (ASBMR).

Focal Dermal Hypoplasia with Osteopathia Striata.

Background: Focal dermal hypoplasia is a genetic disease of multiple systems initially affecting the skin, skeleton, dental, eyes and face with developmental abnormalities and facial dysmorphism. Focal dermal hypoplasia is X-linked dominant disease affecting the ectoderm, mesoderm and endoderm. 95% feature de novo and 90% of these are females. Focal dermal hypoplasia is induced by a mutation in the PORCN gene. Objective: The aim of this article is to present a case of a one-year-old girl child with multi-hypopigmented reticulated atrophic macules and patches grouped in linear mode at the lines of blaschko, skeleton abnormalities, umbilical hernia, developmental delay, hypoplastic nails, syndactyly and lobster claw deformity. Case report: A one-year-old girl child presented to the dermatology clinic with asymptomatic lesions since childhood with no improvement, with multi- hypopigmented skin lesions on the trunk and extremities since birth as linear erosions that heal gradually during few days, leaving peripheral hypopigmentation with hyperpigmentation with anomalies of limbs and nails and delayed development. She was born by normal vaginal delivery and weighed 2.5 kg at birth. None of the family members had such features. She had dental enamel anomaly and partial anodontia in the lower jaw. Sparse hair and partial alopecia (scalp, eyebrows and eyelashes) were recorded. Conclusion: Focal dermal hypoplasia is a congenital skin disease with a unique clinical feature. Thorough examination of the extremities is indicated for early proper genetic counseling and therapy.

A novel NSDHL variant in CHILD syndrome with gastrointestinal manifestations and localized skin involvement.

BACKGROUND: CHILD syndrome is an X-linked dominant disorder associated with pathogenic mutations in the NSDHL gene. The condition is predominantly found in females as it is lethal in males. Most cases present at birth with extensive unilateral ichthyosiform erythroderma involving the trunk and limbs. Milder and less extensive presentations have been reported, leading to misdiagnosis especially during early childhood. METHODS AND RESULTS: We report an adult female of Malay ancestry who presented with minimal skin and limb involvement. She was only diagnosed in adulthood when she presented with gastrointestinal symptoms and worsening of skin manifestations. The clinical diagnosis was suspected after a combination of clinical, pathological and immunohistochemistry correlation, and molecularly confirmed with the discovery of a frameshift variant in NSDHL. The novel variant was inherited from her mother who had some linear hypopigmented patches over the medial aspects of both her arms and right forearm. CONCLUSION: We uncovered a novel frameshift variant associated with presentations that cast a new light on the clinical features of CHILD syndrome.

Thanatophoric dysplasia type 1 with temporal lobe dysplasia: Report of a case along with differential diagnosis.

Thanatophoric dysplasia type 1 (TD1) is a lethal form of osteochondral dysplasia due to mutation of FGFR3 gene. In addition to severe shortening of the limbs there is temporo-occipital lobe dysplasia along with a range of other CNS anomalies. In this report we describe the radiological and anatomical features at autopsy in neonate with TD1 along with the CNS anomalies. We have also summarized the key distinguishing features of TD1 from other common types of osteochondral dysplasia. An accurate diagnosis is important for genetic counseling and impact on future pregnancies.

Early clinical and radiological improvement in a young boy with metaphyseal anadysplasia type 2.

Metaphyseal anadysplasia is a very rare hereditary skeletal dysplasia with onset occurring normally during the second and third years of life, but unlike many other dysplasias, symptoms appear to resolve by adolescence. Two types exist, the more severe form, type 1, with both autosomal dominant and recessive inheritance due to pathogenic variants in MMP13, whilst type 2, an even rarer form is due to biallelic MMP9 variants. To date, only two metaphyseal anadysplasia type 2 families have been reported. We describe a third family, a young boy, born to consanguineous parents, referred at 19 months old for abnormal gait due to bowed legs. Clinical and radiological examination revealed scoliosis, genu varum and metaphyseal abnormalities. A homozygous MMP9 nonsense variant, NM_004994.2:c.1764G>A; p.(Trp588*) was identified. By the age of 39 months, lower limb alignment and metaphyseal features had already significantly improved and scoliosis had disappeared. This case confirms that biallelic MMP9 variants cause this very rare skeletal dysplasia, metaphyseal anadysplasia type 2 but also shows that the skeletal manifestations can improve within a short period time and at an early age.

Developmental malformations resulting from high-dose maternal tamoxifen exposure in the mouse.

Tamoxifen is an estrogen receptor (ER) ligand with widespread use in clinical and basic research settings. Beyond its application in treating ER-positive cancer, tamoxifen has been co-opted into a powerful approach for temporal-specific genetic alteration. The use of tamoxifen-inducible Cre-recombinase mouse models to examine genetic, molecular, and cellular mechanisms of development and disease is now prevalent in biomedical research. Understanding off-target effects of tamoxifen will inform its use in both clinical and basic research applications. Here, we show that prenatal tamoxifen exposure can cause structural birth defects in the mouse. Administration of a single 200 mg/kg tamoxifen dose to pregnant wildtype C57BL/6J mice at gestational day 9.75 caused cleft palate and limb malformations in the fetuses, including posterior digit duplication, reduction, or fusion. These malformations were highly penetrant and consistent across independent chemical manufacturers. As opposed to 200 mg/kg, a single dose of 50 mg/kg tamoxifen at the same developmental stage did not result in overt structural malformations. Demonstrating that prenatal tamoxifen exposure at a specific time point causes dose-dependent developmental abnormalities, these findings argue for more considerate application of tamoxifen in Cre-inducible systems and further investigation of tamoxifen's mechanisms of action.

Terminal osseous dysplasia with pigmentary defects and cardiomyopathy caused by a novel FLNA variant.

Terminal osseous dysplasia with pigmentary defects (TODPD), also known as digitocutaneous dysplasia, is one of the X-linked filaminopathies caused by a variety of FLNA-variants. TODPD is characterized by skeletal defects, skin fibromata and dysmorphic facial features. So far, only a single recurrent variant (c.5217G>A;p.Val1724_Thr1739del) in FLNA has found to be responsible for TODPD. We identified a novel c.5217+5G>C variant in FLNA in a female proband with skeletal defects, skin fibromata, interstitial lung disease, epilepsy, and restrictive cardiomyopathy. This variant causes mis-splicing of exon 31 predicting the production of a FLNA-protein with an in-frame-deletion of 16 residues identical to the miss-splicing-effect of the recurrent TODPD c.5217G>A variant. This mis-spliced transcript was explicitly detected in heart tissue, but was absent from blood, skin, and lung. X-inactivation analyses showed extreme skewing with almost complete inactivation of the mutated allele (>90%) in these tissues, except for heart. The mother of the proband, who also has fibromata and skeletal abnormalities, is also carrier of the FLNA-variant and was diagnosed with noncompaction cardiomyopathy after cardiac screening. No other relevant variants in cardiomyopathy-related genes were found. Here we describe a novel variant in FLNA (c.5217+5G>C) as the second pathogenic variant responsible for TODPD. Cardiomyopathy has not been described as a phenotypic feature of TODPD before.

A unique case of progressive hemifacial microsomia or Parry-Romberg syndrome associated with limb and brain anomalies with normal neurological findings: A review of the literature.

In this report, we describe an unusual case of progressive hemifacial atrophy or Parry-Romberg syndrome in a 10-year-old girl with progressive hemifacial microsomia and limb anomalies who had brain magnetic resonance imaging (MRI) findings of white matter hyper-intensities. Patients typically present with neurological manifestations such as epilepsy, facial pain, and migraines and ophthalmological symptoms in conjunction with white matter lesions. The patient demonstrated normal cognition and psychomotor development despite the presence of white matter lesions in her frontal lobe that is commonly associated with neurological symptoms. This report brings attention to the complicated relationship between facial, limb and brain imaging findings in Parry-Romberg syndrome and differentiates it from hemifacial microsomia syndrome.

Genome sequencing in families with congenital limb malformations.

The extensive clinical and genetic heterogeneity of congenital limb malformation calls for comprehensive genome-wide analysis of genetic variation. Genome sequencing (GS) has the potential to identify all genetic variants. Here we aim to determine the diagnostic potential of GS as a comprehensive one-test-for-all strategy in a cohort of undiagnosed patients with congenital limb malformations. We collected 69 cases (64 trios, 1 duo, 5 singletons) with congenital limb malformations with no molecular diagnosis after standard clinical genetic testing and performed genome sequencing. We also developed a framework to identify potential noncoding pathogenic variants. We identified likely pathogenic/disease-associated variants in 12 cases (17.4%) including four in known disease genes, and one repeat expansion in HOXD13. In three unrelated cases with ectrodactyly, we identified likely pathogenic variants in UBA2, establishing it as a novel disease gene. In addition, we found two complex structural variants (3%). We also identified likely causative variants in three novel high confidence candidate genes. We were not able to identify any noncoding variants. GS is a powerful strategy to identify all types of genomic variants associated with congenital limb malformation, including repeat expansions and complex structural variants missed by standard diagnostic approaches. In this cohort, no causative noncoding SNVs could be identified.

Adult diagnosis of congenital serine biosynthesis defect: A treatable cause of progressive neuropathy.

A woman with ichthyosis, contractures, and progressive neuropathy represents the first case of phosphoserine aminotransferase deficiency diagnosed and treated in an adult. She has novel compound heterozygous mutations in the gene PSAT1. Treatment with high dose oral L-serine completely resolved the ichthyosis. Consideration of this diagnosis is important because early treatment with L-serine repletion can halt progression of neurodegeneration and potentially improve neurological disabilities. As exome sequencing becomes more widely implemented in the diagnostic evaluation of progressive neurodegenerative phenotypes, adult neurologists and geneticists will increasingly encounter later onset manifestations of inborn errors of metabolism classically considered in infancy and early childhood.

Feingold syndrome type 2 in a patient from China.

Feingold syndrome type 2 (FGLDS2, MIM614326) is a genetic congenital malformation syndrome, caused by germline heterozygous deletion of MIR17HG on chromosome 13q31, which is extremely rare worldwide. To date, less than 25 patients have been described in the literature. Here, we report on a 3-year-old girl presented with hip dysplasia, polysyndactyly of the left thumb, brachymesophalangy of the fifth digit, microcephaly, intellectual disability, and growth delay. This is likely to be the first case of Feingold syndrome type 2 ever discovered among Chinese population. Through genetic testing and pedigree analysis, she was identified to have a de novo 4.8-Mb microdeletion at chromosome 13q31.3-q32.1, encompassing MIR17HG, GPC5, and GPC6. Additionally, we detected two common compound heterozygous variants (c.919-2A>G and c.147C>G) in SLC26A4 encoding pendrin protein, as well as a novel heterozygous variant c.985_988del in COMP encoding cartilage oligomeric matrix protein. This case report aims to analyze the microdeletion and the three types of variant detected in the patient, and to explore the association between the genotype and phenotype in patients with Feingold syndrome type 2, which may contribute to further understanding and future diagnosis of this disorder.

Nager syndrome in patient lacking acrofacial dysostosis: Expanding the phenotypic spectrum of SF3B4-related disease.

Nager syndrome epitomizes the acrofacial dysostoses, which are characterized by craniofacial and limb defects. The craniofacial defects include midfacial retrusion, downslanting palpebral fissures, prominent nasal bridge, and micrognathia. Limb malformations typically include hypoplasia or aplasia of radial elements including the thumb. Nager syndrome is caused by haploinsufficiency of SF3B4, encoding a spliceosomal protein called SAP49. Here, we report a patient with a loss of function variant in SF3B4 without acrofacial dysostosis or limb defects, whose reason for referral was developmental and growth delay. This patient is evidence of a broader phenotypic spectrum associated with SF3B4 variants than previously appreciated.

Clinical and molecular characterizations of 11 new patients with type 1 Feingold syndrome: Proposal for selecting diagnostic criteria and further genetic testing in patients with severe phenotype.

Feingold Syndrome type 1 (FS1) is an autosomal dominant disorder due to a loss of function mutations in the MYCN gene. FS1 is generally clinically characterized by mild learning disability, microcephaly, short palpebral fissures, short stature, brachymesophalangy, hypoplastic thumbs, as well as syndactyly of toes, variably associated with organ abnormalities, the most common being gastrointestinal atresia. In current literature, more than 120 FS1 patients have been described, but diagnostic criteria are not well agreed upon, likewise the genotype-phenotype correlations are not well understood. Here, we describe 11 FS1 patients, belonging to six distinct families, where we have identified three novel MYCN mutations along with three pathogenetic variants, the latter which have already been reported. Several patients presented a mild phenotype of the condition and they have been diagnosed as being affected only after segregation analyses of the MYCN mutation identified in the propositus. We also describe here the first ever FS1 patient with severe intellectual disability having a maternally inherited MYCN variant together with an additional GNAO1 mutation inherited paternally. Mutations in the GNAO1 gene are associated with a specific form of intellectual disability and epilepsy, thus the finding of two different rare diseases in the same patient could explain his severe phenotype. Therein, a thorough investigation is merited into the possibility that additional variants in patients with a MYCN mutation and severe phenotype do exist. Finally, in order to guarantee a more reliable diagnosis of FS1, we suggest using both major and minor clinical-molecular diagnostic criteria.

Temperature-dependent autoactivation associated with clinical variability of PDGFRB Asn666 substitutions.

Ocular pterygium-digital keloid dysplasia (OPDKD) presents in childhood with ingrowth of vascularized connective tissue on the cornea leading to severely reduced vision. Later the patients develop keloids on digits but are otherwise healthy. The overgrowth in OPDKD affects body parts that typically have lower temperature than 37°C. We present evidence that OPDKD is associated with a temperature sensitive, activating substitution, p.(Asn666Tyr), in PDGFRB. Phosphorylation levels of PDGFRB and downstream targets were higher in OPDKD fibroblasts at 37°C but were further greatly increased at the average corneal temperature of 32°C. This suggests that the substitution cause significant constitutive autoactivation mainly at lower temperature. In contrast, a different substitution in the same codon, p.(Asn666Ser), is associated with Penttinen type of premature aging syndrome. This devastating condition is characterized by widespread tissue degeneration, including pronounced chronic ulcers and osteolytic resorption in distal limbs. In Penttinen syndrome fibroblasts, equal and high levels of phosphorylated PDGFRB was present at both 32°C and 37°C. This indicates that this substitution causes severe constitutive autoactivation of PDGFRB regardless of temperature. In line with this, most downstream targets were not affected by lower temperature. However, STAT1, important for tissue wasting, did show further increased phosphorylation at 32°C. Temperature-dependent autoactivation offers an explanation to the strikingly different clinical outcomes of substitutions in the Asn666 codon of PDGFRB.

The power of zebrafish models for understanding the co-occurrence of craniofacial and limb disorders.

Craniofacial and limb defects are two of the most common congenital anomalies in the general population. Interestingly, these defects are not mutually exclusive. Many patients with craniofacial phenotypes, such as orofacial clefting and craniosynostosis, also present with limb defects, including polydactyly, syndactyly, brachydactyly, or ectrodactyly. The gene regulatory networks governing craniofacial and limb development initially seem distinct from one another, and yet these birth defects frequently occur together. Both developmental processes are highly conserved among vertebrates, and zebrafish have emerged as an advantageous model due to their high fecundity, relative ease of genetic manipulation, and transparency during development. Here we summarize studies that have used zebrafish models to study human syndromes that present with both craniofacial and limb phenotypes. We discuss the highly conserved processes of craniofacial and limb/fin development and describe recent zebrafish studies that have explored the function of genes associated with human syndromes with phenotypes in both structures. We attempt to identify commonalities between the two to help explain why craniofacial and limb anomalies often occur together.

Clinical and molecular characterization of four patients with Robinow syndrome from different families.

Robinow syndrome (RS) is a rare heterogeneous disorder characterized by short stature, short-limbs, craniofacial, oro-dental abnormalities, vertebral segmentation defects, and frequently genital hypoplasia. Both autosomal dominant and recessive patterns of inheritance are observed with many causative genes. Here, we present the phenotypes and genotypes of four children with RS from different Indian families. Sequence variants were identified in genes ROR2, DVL1, and DVL3. Our results expand the mutational spectrum of RS and we also highlight the radiological changes in the radius and ulna in patients with ROR2 sequence variants which are primarily characteristic for ROR2 related RS but have been reported in WNT5A related RS.

Earlier detection of hypochondroplasia: A large single-center UK case series and systematic review.

Hypochondroplasia (HCH) is a rare autosomal dominant skeletal dysplasia condition caused by FGFR3 mutations leading to disproportionate short stature. Classically HCH presents in toddlers or school-age children, as limb-to-trunk disproportion and is often mild and easily overlooked during infancy. We report experiences from a single-center UK HCH-cohort of 31 patients, the rate of antenatal HCH detection in our cohort (13/31, 41.9%) and describe relevant case-data for this subset of 13 patients. Inclusion criteria were patients with confirmed molecular HCH diagnosis (by age 3 years) and presenting with short long-bones or large head size on antenatal ultrasound scan. We then conducted a systematic literature review using PUBMED and MEDLINE, analyzing patients with HCH and related antenatal findings. Antenatally suspected (with subsequent molecular confirmation) HCH has been reported 15 times in the literature (2004-2019). Key markers (consistent in both groups) included reduced; femur length, humeral length and increased; biparietal diameter and head circumference. HCH is increasingly detected both antenatally and in infancy, contrary to previous descriptions. This is likely due to greater HCH awareness, improved imaging, and easier molecular testing. Thus, one should consider HCH outside the classical presenting period. Studying the natural history of younger patients with HCH is important with the advent of several targeted FGFR3 therapies currently in trials for Achondroplasia, that may soon be trialed in HCH.