Identification of a founder effect involving n.197C>T variant in RMRP gene associated to cartilage-hair hypoplasia syndrome in Brazilian patients.

Cartilage-hair hypoplasia syndrome (CHH) is an autosomal recessive disorder frequently linked to n.72A>G (previously known as n.70A>G and n.71A>G), the most common RMRP variant worldwide. More than 130 pathogenic variants in this gene have already been described associated with CHH, and founder alterations were reported in the Finnish and Japanese populations. Our previous study in Brazilian CHH patients showed a high prevalence of n.197C>T variant (former n.195C>T and n.196C>T) when compared to other populations. The aim of this study was to investigate a possible founder effect of the n.197C>T variant in the RMRP gene in a series of CHH Brazilian patients. We have selected four TAG SNPs within chromosome 9 and genotyped the probands and their parents (23 patients previously described and nine novel). A common haplotype to the n.197C>T variant carriers was identified. Patients were also characterized for 46 autosomal Ancestry Informative Markers (AIMs). European ancestry was the most prevalent (58%), followed by African (24%) and Native American (18%). Our results strengthen the hypothesis of a founder effect for the n.197C>T variant in Brazil and indicate that this variant in the RMRP gene originated from a single event on chromosome 9 with a possible European origin.

A mesomelic skeletal dysplasia, Kantaputra-like, not related to HOXD cluster region, and with phenotypic gender differences.

Mesomelic skeletal dysplasia is a heterogeneous group of skeletal disorders that has grown since the molecular basis of these conditions is in the process of research and discovery. Here, we report a Brazilian family with eight affected members over three generations with a phenotype similar to mesomelic Kantaputra dysplasia. This family presents marked shortening of the upper limbs with hypotrophy of the lower limbs and clubfeet without synostosis. Array-based CNV analysis and exome sequencing of four family members failed to show any region or gene candidate. Interestingly, males were more severely affected than females in this family, suggesting that gender differences could play a role in the phenotypic expressivity of this condition.

Czech dysplasia mimicking rheumatoid arthritis: Case series and literature review.

OBJECTIVE: This study reported a family with most members affected by Czech dysplasia. We examined the patients' clinical, laboratory, and imaging characteristics and evaluated their functional capacity using the Stanford Health Assessment Questionnaire-Disability Index. METHODS: The method used was case series description and literature review. RESULTS: This study showed that the pathogenic variant c.823C>T in the COL2A1 gene, which is a characteristic of Czech dysplasia, was found in 12 Brazilian individuals. Half of the patients in this family met the criteria for rheumatoid arthritis (RA) based on the 2010 American College of Rheumatology/European League Against Rheumatism classification criteria. Patients had arthritis in their hand joints, synovitis detected by ultrasound, and alterations in inflammatory tests. The Stanford Health Assessment Questionnaire-Disability Index assessment revealed that all patients exhibited moderate-to-severe functional disability. What distinguish Czech dysplasia from RA are an autosomal dominant inheritance pattern, platyspondyly, sensorineural hearing loss, and shortening of the metatarsal bones. CONCLUSIONS: It is important to consider Czech dysplasia as a potential differential diagnosis for RA. This autosomal dominant skeletal dysplasia is associated with normal height, short metatarsals, platyspondyly, hearing loss, enlarged epiphyses, and precocious osteoarthritis. Inflammatory findings such as arthritis, synovitis, and alteration of inflammatory markers may also be present in individuals with Czech dysplasia.

Achondroplasia in Latin America: practical recommendations for the multidisciplinary care of pediatric patients.

BACKGROUND: Achondroplasia is the most common bone dysplasia associated with disproportionate short stature, and other comorbidities, such as foramen magnum stenosis, thoracolumbar kyphosis, lumbar hyperlordosis, genu varum and spinal compression. Additionally, patients affected with this condition have higher frequency of sleep disorders, ear infections, hearing loss and slowed development milestones. Considering these clinical features, we aimed to summarize the regional experts' recommendations for the multidisciplinary management of patients with achondroplasia in Latin America, a vast geographic territory with multicultural characteristics and with socio-economical differences of developing countries. METHODS: Latin American experts (from Argentina, Brazil, Chile and Colombia) particiáted of an Advisory Board meeting (October 2019), and had a structured discussion how patients with achondroplasia are followed in their healthcare centers and punctuated gaps and opportunities for regional improvement in the management of achondroplasia. RESULTS: Practical recommendations have been established for genetic counselling, prenatal diagnosis and planning of delivery in patients with achondroplasia. An outline of strategies was added as follow-up guidelines to specialists according to patient developmental phases, amongst them neurologic, orthopedic, otorhinolaryngologic, nutritional and anthropometric aspects, and related to development milestones. Additionally, the role of physical therapy, physical activity, phonoaudiology and other care related to the quality of life of patients and their families were discussed. Preoperative recommendations to patients with achondroplasia were also included. CONCLUSIONS: This study summarized the main expert recommendations for the health care professionals management of achondroplasia in Latin America, reinforcing that achondroplasia-associated comorbidities are not limited to orthopedic concerns.

Molecular analysis of the CTSK gene in a cohort of 33 Brazilian families with pycnodysostosis from a cluster in a Brazilian Northeast region.

BACKGROUND: Pycnodysostosis is an autosomal recessive skeletal dysplasia, the prevalence of which is estimated to be low (1 per million). Nevertheless, in recent years we have found 27 affected individuals from 22 families in Ceará State, a region of the Brazilian Northeast, giving a local prevalence of 3 per million. This local prevalence associated with a high parental consanguinity, suggesting a possible founder effect, prompted us to perform a molecular investigation of these families to test this hypothesis. METHODS: The CTSK gene was sequenced by the Sanger method in the patients and their parents. In addition to 18 families from Ceará, this study also included 15 families from other Brazilian regions. We also investigated the origin of each family from the birthplace of the parents and/or grandparents. RESULTS: We have studied 39 patients, including 33 probands and 6 sibs, from 33 families with pycnodysostosis and identified six mutations, five previously described (c.436G>C, c.580G>A, c.721C>T, c.830C>T and c.953G>A) and one novel frameshift (c.83dupT). This frameshift variant seems to have a single origin in Ceará State, since the haplotype study using the polymorphic markers D1S2344, D1S442, D1S498 and D1S2715 suggested a common origin. Most of the mutations were found in homozygosity in the patients from Ceará (83.3 %) while in other states the mutations were found in homozygosity in half of patients. We have also shown that most of the families currently living outside of Ceará have northeastern ancestors, suggesting a dispersion of these mutations from the Brazilian Northeast. CONCLUSIONS: The high frequency of pycnodysostosis in Ceará State is the consequence of the high inbreeding in that region. Several mutations, probably introduced a long time ago in Ceará, must have spread due to consanguineous marriages and internal population migration. However, the novel mutation seems to have a single origin in Ceará, suggestive of a founder effect.

Frequency of the allelic variant c.1150T > C in exon 10 of the fibroblast growth factor receptor 3 (FGFR3) gene is not increased in patients with pathogenic mutations and related chondrodysplasia phenotypes.

Mutations in the FGFR3 gene cause the phenotypic spectrum of FGFR3 chondrodysplasias ranging from lethal forms to the milder phenotype seen in hypochondroplasia (Hch). The p.N540K mutation in the FGFR3 gene occurs in ∼70% of individuals with Hch, and nearly 30% of individuals with the Hch phenotype have no mutations in the FGFR3, which suggests genetic heterogeneity. The identification of a severe case of Hch associated with the typical mutation c.1620C > A and the occurrence of a c.1150T > C change that resulted in a p.F384L in exon 10, together with the suspicion that this second change could be a modulator of the phenotype, prompted us to investigate this hypothesis in a cohort of patients. An analysis of 48 patients with FGFR3 chondrodysplasia phenotypes and 330 healthy (control) individuals revealed no significant difference in the frequency of the C allele at the c.1150 position (p = 0.34). One patient carrying the combination `pathogenic mutation plus the allelic variant c.1150T > C' had a typical achondroplasia (Ach) phenotype. In addition, three other patients with atypical phenotypes showed no association with the allelic variant. Together, these results do not support the hypothesis of a modulatory role for the c.1150T > C change in the FGFR3 gene.

Downregulation of 14q32 microRNAs in Primary Human Desmoplastic Medulloblastoma.

Medulloblastoma (MB) is one of the most common pediatric cancers, likely originating from abnormal development of cerebellar progenitor neurons. MicroRNA (miRNA) has been shown to play an important role in the development of the central nervous system. Microarray analysis was used to investigate miRNA expression in desmoplastic MB from patients diagnosed at a young age (1 or 2 years old). Normal fetal or newborn cerebellum was used as control. A total of 84 differentially expressed miRNAs (64 downregulated and 20 upregulated) were found. Most downregulated miRNAs (32/64) were found to belong to the cluster of miRNAs at the 14q32 locus, suggesting that this miRNA locus is regulated as a module in MB. Possible mechanisms of 14q32 miRNAs downregulation were investigated by the analysis of publicly available gene expression data sets. First, expression of estrogen-related receptor-γ (ESRRG), a reported positive transcriptional regulator of some 14q32 miRNAs, was found downregulated in desmoplastic MB. Second, expression of the parentally imprinted gene MEG3 was lower in MB in comparison to normal cerebellum, suggesting a possible epigenetic silencing of the 14q32 locus. miR-129-5p (11p11.2/7q32.1), miR-206 (6p12.2), and miR-323-3p (14q32.2), were chosen for functional studies in DAOY cells. Overexpression of miR-129-5p using mimics decreased DAOY proliferation. No effect was found with miR-206 or miR-323 mimics.

Scalp lesions in Turner syndrome: a result of lymphoedema?

Lymphoedema and skin naevi are common in children with Turner syndrome (TS). Lymphoedema in the early stages of fetal life is thought to cause several of the phenotypic characteristics in patients with TS such as nuchal folds and pterygium colli. We present two patients with TS who have unusual lesions on the scalp. The first patient had an oval circumscribed lesion. Two biopsies were obtained from the lesion. Increased numbers of collagen fibres were seen in the reticular dermis suggesting the diagnosis of connective tissue naevus. The second patient presented with an area with skin folds on the scalp, similar to cutis verticis gyrata. Although unusual in TS, both lesions could be considered as resolving stages of lymphoedema. We suggest that karyotyping should be performed in cases of female infants presenting with similar lesions.

Importância da avaliação genético-clínica na hidrocefalia / Importance of the clinical genetics evaluation on hydrocephalus

Os objetivos deste estudo foram caracterizar a presença de possíveis quadros de etiologia genética entre portadores de hidrocefalia congênita de etiologia não anteriormente esclarecida e confirmar aqueles com etiologia identificada previamente. A casuística compôs-se de 16 pacientes portadores de hidrocefalia congênita. O protocolo de investigação incluiu anamnese, investigação de história familial, exame clínico-dismorfológico, tomografia computadorizada ou ressonância magnética de sistema nervoso central, radiografia vertebral simples, cariótipo e estudo dismorfológico. Para análise dos resultados, a casuística foi dividida em dois grupos. O Grupo I (3M:6F) caracterizado por indivíduos com hidrocefalia e sinais clínicos inespecíficos; o Grupo II (7M), em que os indivíduos apresentavam hidrocefalia congênita e sinais sugestivos do espectro da doença L1. Orientação genética específica foi possível em 11 casos. Os resultados demonstram a heterogeneidade etiológica envolvida na hidrocefalia, evidenciando a necessidade de avaliação clínico-dismorfológica como instrumento complementar na investigação dessa condição clínica.