Cornelia de Lange Syndrome

Cohesin composition and dosage independently affect early development in zebrafish

Cohesin, a chromatin-associated protein complex with four core subunits (Smc1a, Smc3, Rad21 and either Stag1 or 2), has a central role in cell proliferation and gene expression in metazoans. Human developmental disorders termed 'cohesinopathies' are characterized by germline variants of cohesin or its regulators that do not entirely eliminate cohesin function. However, it is not clear whether mutations in individual cohesin subunits have independent developmental consequences. Here, we show that zebrafish rad21 or stag2b mutants independently influence embryonic tailbud development. Both mutants have altered mesoderm induction, but only homozygous or heterozygous rad21 mutation affects cell cycle gene expression. stag2b mutants have narrower notochords and reduced Wnt signaling in neuromesodermal progenitors as revealed by single-cell RNA sequencing. Stimulation of Wnt signaling rescues transcription and morphology in stag2b, but not rad21, mutants. Our results suggest that mutations altering the quantity versus composition of cohesin have independent developmental consequences, with implications for the understanding and management of cohesinopathies.

An Analysis of Associated Conditions and the Relationship Between the Severity of Hand Manifestations With That of the Forearm in Ulnar Longitudinal Deficiency

PURPOSE

A deeper investigation of medical and musculoskeletal conditions in patients with ulnar longitudinal deficiency (ULD) is needed. The association between the severity of the manifestations of ULD in the hands and forearms has not been firmly established. The purpose of this study was to describe the medical and musculoskeletal conditions associated with ULD and examine the relationship between hand and forearm anomalies.

METHODS

The Congenital Upper Limb Differences registry was queried for all patients with a diagnosis of ULD, as defined by the Oberg-Manske-Tonkin classification system, between 2014 and 2020. The patients' demographic information, medical and musculoskeletal comorbidities, radiographs, and clinical images were reviewed. The participants were classified using the Bayne, Cole and Manske, and Ogino classification systems.

RESULTS

Of 2,821 patients from the Congenital Upper Limb Differences registry, 75 patients (2.7%) with ULD (14 bilateral), with 89 affected extremities, were included. Hand anomalies were present in 93% of the patients. Approximately 19% of the patients had an associated medical comorbidity, and 20% of the patients had an associated musculoskeletal condition. Cardiac anomalies were present in 8.0% of the patients, and 12% of the patients had a lower extremity abnormality. Radial head dislocation was observed in 13 of 18 patients with Bayne type II or III ULD compared with 8 of 43 patients with other types of unilateral ULD. There was a significant positive association among the Bayne and Ogino, Bayne and Cole/Manske, and Ogino and Cole/Manske classification systems in patients with unilateral ULD.

CONCLUSIONS

Associated medical and musculoskeletal conditions are common in patients with ULD, of which cardiac and lower extremity abnormalities are most frequently observed. There is a significant positive association between the severity of forearm anomalies and that of hand anomalies in patients with unilateral ULD. All patients with ULD should undergo a thorough cardiac evaluation by their pediatrician or a pediatric cardiologist.

TYPE OF STUDY/LEVEL OF EVIDENCE

Symptom prevalence study III.

A 16-Day-Old Infant with a Clinical Diagnosis of Classical Cornelia de Lange Syndrome

Cornelia de Lange syndrome (CdLS) is a rare syndromic genetic disorder characterized by multiple congenital anomalies with upper limb reduction defects, along with cardiac, gastrointestinal, and genitourinary defects. It is caused by genetic variations in the chromatin regulator genes, most commonly, the cohesin complex. Even though molecular genetic testing is highly recommended to confirm the diagnosis, high costs and unavailability in some settings are significant setbacks, and clinical criteria could be used. The typical craniofacial features include generalized hirsutism, synophrys, microbrachycephaly, highly arched eyebrows, and long eyelashes, along with height and weight below the 5th percentile. In this paper, we present a case of a 16-day-old male infant in whom a clinical diagnosis of classical CdLS was made.

[Malformations of hand and forearm : Conspicuous postpartum]

Many congenital malformations of the hand and forearm, e. g. polydactyly, thumb duplication, syndactyly and radial aplasia, are already evident at birth and newborns are promptly referred to specialized departments. In contrast, orthopedic surgeons are often confronted with malformations of the hand and forearm, which gradually become clinically conspicuous during growth. This review article focuses on these specific malformations, which regularly upset the patients in practice and in most cases the parents even more so. In addition to the diagnostics and differential diagnostics, the conservative and surgical treatment options are presented.