Hearing loss, cleft palate, and congenital hip dysplasia in female carriers of an intragenic deletion of AMMECR1

The usefulness of universal ultrasound before hospital discharge for early diagnosing hip dysplasia in Korean neonates with breech presentation in a single center: A retrospective study

Developmental dysplasia of the hip (DDH) is a broad-spectrum disorder. Early diagnosis and treatment are important for improved prognosis and a lower risk of long-term complications. Selecting high-risk infants is important for the early diagnosis of DDH using ultrasonography; however, there are no standard international guidelines. This study aimed to identify the usefulness of universal ultrasound before hospital discharge in breech-born neonates and proposes selective ultrasound for high-risk patients. A retrospective chart review was conducted to identify breech-born neonates who underwent hip ultrasonography before discharge for the detection of DDH between 2019 and 2023. Patients were categorized into DDH and non-DDH groups according to the ultrasound results. We compared sex, gestational age, birth weight, first-born status, twin pregnancy, associated anomalies, presence of symptoms, physical examination results, and timing of the first hip ultrasound. The medical records of the mothers were reviewed to identify the amount of amniotic fluid and duration of breech presentation. This study included 102 patients, of whom 62 and 40 were assigned to the non-DDH and DDH groups, respectively. Congenital anomalies, positive symptoms, and positive physical examination results were significant risk factors. However, female sex, first-born status, and oligohydramnios were not statistically significant. The duration of breech presentation during pregnancy was not significant. Additionally, the risk of Pavlik harnesses was higher in patients who underwent a positive physical examination. Universal ultrasonography before discharge is not recommended for the early diagnosis of DDH in all breech-born neonates because of the high rate of overdiagnosis. We recommend that ultrasonography be performed in patients with congenital anomalies, except for foot problems, or in those with a positive physical examination conducted by trained specialists.

Identification of KANSL1 as a novel pathogenic gene for developmental dysplasia of the hip

Developmental dysplasia of the hip (DDH) is a common anomaly leading to adult osteoarthritis. Environmental and genetic factors contribute to DDH, but its exact genetic mechanism is unclear. In this study, we used whole exome sequencing to identify the causative gene of a DDH pedigree. A rare missense variant in KANSL1 (c.C767T; p.S256F) was identified as the pathogenic cause of DDH. Subsequent mutation screening showed another missense variant in 1 of 200 sporadic patients. Kansl1-mutated mice showed reduced chondrocytes in the acetabulum and a decrease in the cartilage matrix, which may be DDH phenotype-related abnormalities. Furthermore, functional studies showed that cell proliferation was delayed and Mmp13 expression was abnormally upregulated in chondrocytes differentiated from Kansl1 mutant mouse embryonic stem cells. In conclusion, our findings suggest that KANSL1 is a novel pathogenic gene for DDH. The identification of KANSL1 variants has great diagnostic value for identifying individuals with DDH. KEY MESSAGES: Developmental dysplasia of the hip (DDH) is a common anomaly causing adult osteoarthritis. Environmental and genetic factors contribute to DDH, but its exact genetic mechanism is unclear. Using high-throughput whole exome sequencing, we found a novel variant in KANSL1 that was co-inherited by all severely affected individuals diagnosed with DDH from a three-generation family. Further analysis revealed that a Kansl1 variant in mice reduced the number of chondrocytes and decreased cartilage matrix, and mouse embryonic stem differentiation assay showed cartilage defects. These findings indicate a direct association between KANSL1 and hip development, expanding the pathogenic gene spectrum in DDH and providing insight into potential new targets for diagnosing and treating hip dysplasia.