Hand hyperphalangism leading to shortened index fingers with ulnar deviation, hallux valgus, mild facial dysmorphism and respiratory compromise requiring assisted ventilation are the key features of Chitayat syndrome. This condition results from the recurrent heterozygous missense variant NM_006494.2:c.266A>G; p.(Tyr89Cys) in ERF on chromosome 19q13.2, encoding the ETS2 repressor factor (ERF) protein. The pathomechanism of Chitayat syndrome is unknown. To date, seven individuals with Chitayat syndrome and the recurrent pathogenic ERF variant have been reported in the literature. Here, we describe six additional individuals, among them only one presenting with a history of assisted ventilation, and the remaining presenting with variable pulmonary phenotypes, including one individual without any obvious pulmonary manifestations. Our findings widen the phenotype spectrum caused by the recurrent pathogenic variant in ERF, underline Chitayat syndrome as a cause of isolated skeletal malformations and therefore contribute to the improvement of diagnostic strategies in individuals with hand hyperphalangism.

Acetabular protrusion (AP) is present in 33 to 55% of patients with osteogenesis imperfecta (OI). Even though the finding is relatively common, it is poorly described in pediatric patients. The objective of this study was to describe the incidence and associations of AP in pediatric OI patients. We retrospectively and cross-sectionally evaluated clinical histories and radiographic findings of OI patients aged 2 to 19.5 years, recording sex, age, severity, anthropometric measurements, ambulation status, femoral fractures history, and occurrence of orthopaedic surgeries and nephropathy. AP was considered present when the center-edge (CE) angle was more than 35 degrees and the acetabular line crossed the Kohler's line by more than 1 and 3 mm in boys and girls, respectively, and 3 and 6 mm in adult males and females, respectively. The association with risk factors and complications was analyzed through univariate and multivariate logistic regression. A total of 71 children were evaluated. The median age was 8.6 years, and 54.9% of them had moderate to severe forms of OI. In 71.8% of the children, an abnormal CE angle was found, being frequent in mild, moderate, and severe cases. AP was present in 22.5% of all patients and in 41% of children with moderate to severe OI, and was significantly associated with older ages (p = 0.0062) and nonwalking status (p = 0.0093). We found a high prevalence of AP in children with moderate to severe forms of OI, which was present even at younger ages. In addition, we found a significant increase in the number of children with abnormal CE angles even in those with mild forms of OI. The presence of AP was associated with the severity of the OI and age, and in a negative association with the ambulatory status.

Spondylocarpotarsal synostosis syndrome (SCT) is a very rare skeletal dysplasia characterized by vertebral, carpal, and tarsal fusion; growth retardation; and mild dysmorphic facial features. Variants in FLNB, MYH3, and RFLNA have been implicated in this dysplasia. We report the clinical and radiological follow-up of seven SCT pediatric cases associated with biallelic FLNB variants, from four Argentinian families. The seven cases share previously described facial characteristics: round facies, large eyes, and wide based nose; all of them had variable height deficit, in one case noted early in life. Other findings included clinodactyly, joint limitation without bone fusion, neurosensorial hearing loss, and ophthalmological compromise. All cases presented with spinal fusion with variable severity and location, carpal bones coalition, and also delay in carpal ossification. The heterozygous carrier parents had normal height values to −2.5 score standard deviation, without skeletal defects detected. Three different FLNB variants, one nonsense and two frameshift, were detected, all of which were predicted to result in a truncated protein or are degraded by nonsense mediated decay. All cases had at least one copy of the nonsense variant, c.1128C> G; p. (Tyr376*), suggesting the presence of a common ancestor.