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.

Holoprosencephaly (HPE) is a spectrum of brain and facial malformations primarily reflecting genetic factors, such as chromosomal abnormalities and gene mutations. Here, we present a clinical and molecular analysis of 195 probands with HPE or microforms; approximately 72% of the patients were derived from the Latin American Collaborative Study of Congenital Malformations (ECLAMC), and 82% of the patients were newborns. Alobar HPE was the predominant brain defect in almost all facial defect categories, except for patients without oral cleft and median or lateral oral clefts. Ethmocephaly, cebocephaly, and premaxillary agenesis were primarily observed among female patients. Premaxillary agenesis occurred in six of the nine diabetic mothers. Recurrence of HPE or microform was approximately 19%. The frequency of microdeletions, detected using Multiplex Ligation-dependant Probe Amplification (MLPA) was 17% in patients with a normal karyotype. Cytogenetics or QF-PCR analyses revealed chromosomal anomalies in 27% of the probands. Mutational analyses in genes SHH, ZIC2, SIX3 and TGIF were performed in 119 patients, revealing eight mutations in SHH, two mutations in SIX3 and two mutations in ZIC2. Thus, a detailed clinical description of new HPE cases with identified genetic anomalies might establish genotypic and phenotypic correlations and contribute to the development of additional strategies for the analysis of new cases.

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.

The aim of this study was to characterize the possibility of genetic etiology in a group of individuals with congenital hydrocephalus in which the etiology was indeterminate and to confirm that earlier diagnosed. The casuistry was composed by 16 individuals with congenital hydrocephalus. Investigation protocol included anamnesis, familial investigation, physical examination, computerized tomography or magnetic resonance image of head, vertebral column X-ray, karyotype and dysmorphological study. Results were analyzed in two groups. In Group I (3M:9F) was composed by hydrocephalus associated with unspecific signs. Group II (7 males) had findings of epectrum of L1 disease. Genetic counseling could be offered in 11 cases. These results demonstrate the great etiological heterogeneity of congenital hydrocephalus and reinforce the importance of dysmphology evaluation as an important complementary investigation.