Biallelic variants in ADAMTS15 cause a novel form of distal arthrogryposis

Purpose We aimed to identify the underlying genetic cause for a novel form of distal arthrogryposis. Methods Rare variant family-based genomics, exome sequencing, and disease-specific panel sequencing were used to detect ADAMTS15 variants in affected individuals. Adamts15 expression was analyzed at the single-cell level during murine embryogenesis. Expression patterns were characterized using in situ hybridization and RNAscope. Results We identified homozygous rare variant alleles of ADAMTS15 in 5 affected individuals from 4 unrelated consanguineous families presenting with congenital flexion contractures of the interphalangeal joints and hypoplastic or absent palmar creases. Radiographic investigations showed physiological interphalangeal joint morphology. Additional features included knee, Achilles tendon, and toe contractures, spinal stiffness, scoliosis, and orthodontic abnormalities. Analysis of mouse whole-embryo single-cell sequencing data revealed a tightly regulated Adamts15 expression in the limb mesenchyme between embryonic stages E11.5 and E15.0. A perimuscular and peritendinous expression was evident in in situ hybridization in the developing mouse limb. In accordance, RNAscope analysis detected a significant coexpression with Osr1, but not with markers for skeletal muscle or joint formation. Conclusion In aggregate, our findings provide evidence that rare biallelic recessive trait variants in ADAMTS15 cause a novel autosomal recessive connective tissue disorder, resulting in a distal arthrogryposis syndrome

Loss of the BMP Antagonist, SMOC-1, Causes Ophthalmo-Acromelic (Waardenburg Anophthalmia) Syndrome in Humans and Mice

Ophthalmo-acromelic syndrome (OAS), also known as Waardenburg Anophthalmia syndrome, is defined by the combination of eye malformations, most commonly bilateral anophthalmia, with post-axial oligosyndactyly. Homozygosity mapping and subsequent targeted mutation analysis of a locus on 14q24.2 identified homozygous mutations in SMOC1 (SPARC-related modular calcium binding 1) in eight unrelated families. Four of these mutations are nonsense, two frame-shift, and two missense. The missense mutations are both in the second Thyroglobulin Type-1 (Tg1) domain of the protein. The orthologous gene in the mouse, Smoc1, shows site- and stage-specific expression during eye, limb, craniofacial, and somite development. We also report a targeted pre-conditional gene-trap mutation of Smoc1 (Smoc1tm1a) that reduces mRNA to ∼10% of wild-type levels. This gene-trap results in highly penetrant hindlimb post-axial oligosyndactyly in homozygous mutant animals (Smoc1tm1a/tm1a). Eye malformations, most commonly coloboma, and cleft palate occur in a significant proportion of Smoc1tm1a/tm1a embryos and pups. Thus partial loss of Smoc-1 results in a convincing phenocopy of the human disease. SMOC-1 is one of the two mammalian paralogs of Drosophila Pentagone, an inhibitor of decapentaplegic. The orthologous gene in Xenopus laevis, Smoc-1, also functions as a Bone Morphogenic Protein (BMP) antagonist in early embryogenesis. Loss of BMP antagonism during mammalian development provides a plausible explanation for both the limb and eye phenotype in humans and mice

PARTIAL TRISOMY 2p24 -> pter AND MONOSOMY 18q22.1 -> pter RESULTING FROM PARENTAL TRANSLOCATION

WOS: 000337197200007PubMed ID: 24032288Partial trisomy 2p24 -> pter and monosomy 18q22.1 -> qter resulting from parental translocation: This is a report of a 6 month-old boy with a partial trisomy 2p24 -> pter and monosomy 18q22 -> qter. This is the first case presenting this unbalanced translocation with phenotypic features. The patient had growth and developmental retardation, facial dysmorphism, cleft palate, congenital cardiopathy, hypospadias, evantration of diaphragm and deafness. Cranial MRI showed mild ventricular dilatation. Cytogenetic analysis of the patient and his parents revealed a karyotype 46,XY, der(18), t(2;18)(p24;q22)mat in the patient. Subtelomeric FISH analysis confirmed the cytogenetic findings. Phenotypic features were consistent with either partial trisomy 2p or deletion 18q

Partial trisomy 2p24›pter and monosomy 18q22.1›qter resulting from parental translocation

PubMed ID: 24032288This is a report of a 6 month-old boy with a partial trisomy 2p24›pter and monosomy 18q22›qter. This is the first case presenting this unbalanced translocation with phenotypic features. The patient had growth and developmental retardation, facial dysmorphism, cleft palate, congenital cardiopathy, hypospadias, evantration of diaphragm and deafness. Cranial MRI showed mild ventricular dilatation. Cytogenetic analysis of the patient and his parents revealed a karyotype 46,XY, der(18), t(2;18)(p24;q22)mat in the patient. Subtelomeric FISH analysis confirmed the cytogenetic findings. Phenotypic features were consistent with either partial trisomy 2p or deletion 18q