To report a rare case of Desbuquois dysplasia Type 1 (DBQD1) diagnosed prenatally, caused by mutations in the CANT1 gene. DBQD1 is an autosomal recessive skeletal dysplasia with severe disproportionate dwarfism, joint laxity, and multiple skeletal anomalies. A 26-year-old woman, gravida 3, para 1, abortus 1, was referred due to short femur (FL) and humerus (HL) lengths on ultrasound. The patient and her husband are consanguineous. Ultrasound at our clinic revealed a hypoplastic thorax, severe limb anomalies, brachydactyly, overlapping fingers, clubfoot, and rocker-bottom feet, along with ventricular septal defects (VSDs). Genetic testing identified a homozygous pathogenic variant in the CANT1 gene (c.902_906dup, p.Ser303AlafsTer21). Both parents were heterozygous carriers. Following genetic counseling, the family opted for pregnancy termination. This case highlights the importance of comprehensive genetic testing and early, precise diagnosis for informed decision-making in managing rare skeletal dysplasias.

Multiple epiphyseal dysplasia (MED) is a heterogeneous group of chondrodysplasia characterized by arthralgia, early onset osteoarthropathy, and the radiographic findings of small, flat, and irregular-shaped epiphyses. Some patients with MED have mild short stature as well. MED is genetically heterogeneous caused by pathogenic variants in COMP, MATN3, COL9A1, COL9A2, COL9A3, and SLC26A2. In 2017, pathogenic variants in CANT1, which are responsible for Desbuquois dysplasia, have also been reported in the genetic etiology of MED. To date, only three patients have been reported with CANT1-related MED. Herein, we present clinical and radiographic findings of six additional patients from five unrelated families, all sharing the same c.375G > C; p.(Trp125Cys) variant in CANT1 gene. These patients exhibited the features of multiple epiphyseal dysplasia, along with some similarities to Desbuquois dysplasia, thereby broadening the clinical spectrum of CANT1-related disorders.

Skeletal disorders encompass a wide array of conditions, many of which are associated with short stature. Among these, Desbuquois dysplasia is a rare but severe condition characterized by profound dwarfism, distinct facial features, joint hypermobility with multiple dislocations, and unique vertebral and metaphyseal anomalies. Desbuquois dysplasia is inherited in an autosomal recessive manner, with both the DBQD1 (MIM 251450) and DBQD2 (MIM 615777) forms resulting from biallelic mutations. Specifically, DBQD1 is associated with homozygous or compound heterozygous mutations in the CANT1 gene, while DBQD2 can result from mutations in either the CANT1 or XYLT1 genes. This review synthesizes the findings of 111 published case reports, including 54 cases of DBQD1, 39 cases of DBQD2, and 14 cases of the Kim variant (DDKV). Patients in this cohort had a median birth weight of 2505 g, a median length of 40 cm, and a median occipitofrontal circumference of 33 cm. The review highlights the phenotypic variations across Desbuquois dysplasia subtypes, particularly in facial characteristics, joint dislocations, and bone deformities. Genetic analyses revealed a considerable diversity in mutations, with over 35% of cases involving missense mutations, primarily affecting the CANT1 gene. Additionally, approximately 60% of patients had a history of parental consanguinity, indicating a potential genetic predisposition in certain populations. The identified mutations included deletions, insertions, and nucleotide substitutions, many of which resulted in premature stop codons and the production of truncated, likely nonfunctional proteins. These findings underscore the genetic and clinical complexity of Desbuquois dysplasia, highlighting the importance of early diagnosis and the potential for personalized therapeutic approaches. Continued research is essential to uncover the underlying mechanisms of this disorder and improve outcomes for affected individuals through targeted treatments.

Desbuquois dysplasia type 1 (DBQD1) is a recessive chondrodysplasia caused by mutations in the CANT1 gene, encoding for the Golgi Calcium-Activated Nucleotidase 1 (CANT1). The enzyme hydrolyzes UDP, the by-product of glycosyltransferase reactions, but it might play other roles in different cell types. Using a Cant1 knock-out mouse, we demonstrated that CANT1 is crucial for glycosaminoglycan (GAG) synthesis; however, its impact on the biochemical properties of cartilage proteoglycans remains unknown. Thus, in this work, we characterized decorin and aggrecan from primary chondrocyte cultures and cartilage biopsies of mutant mice at post-natal day 4 by Western blots and further investigated their distribution in the cartilage extracellular matrix (ECM) by immunohistochemistry. We demonstrated that the GAG synthesis defect caused by CANT1 impairment led to the synthesis and secretion of proteoglycans with shorter GAG chains compared with wild-type animals. However, this alteration did not result in the synthesis and secretion of decorin and aggrecan in the unglycanated form. Interestingly, the defect was not cartilage-specific since also skin decorin showed a reduced hydrodynamic size. Finally, immunohistochemical studies in epiphyseal sections of mutant mice demonstrated that the proteoglycan structural defect moderately affected decorin distribution in the ECM.

Desbuquois dysplasia (DBQD) is an uncommon, autosomal recessive disorder with multiple joint dislocations. It is caused by pathogenic variants in CANT1 (calcium-activated nucleotidase 1) [NM_001159773.2]. This study adds to the scant data of nine reported antenatal phenotypes of DBQD. The present paper describes two unrelated consanguineous families with antenatal features of lethal skeletal dysplasia. The defining radiological changes were identified in only one patient who presented in the late second and third trimesters. Solo exome sequencing was performed and two previously reported homozygous variants c.896C>T (p.Pro299Leu) in patient 1 and c.902_906dup (p.Ser303fs*20) in patient 2 were identified. This study highlights the fetal presentations in DBQD and adds to its phenotypic spectrum. A complete clinical workup, including fetal autopsy and radiographs is essential to confirm the diagnosis of lethal skeletal dysplasia. Molecular diagnosis remains the diagnostic modality to define the causative variant. A definitive diagnosis is essential to inform management and offer reproductive care.