Neonatal mucolipidosis type II alpha/beta due to compound heterozygosity for a known and novel GNPTAB mutation, and a concomitant heterozygous change in SERPINF1 inherited from the mother.

We report on a newborn with IUGR, rhizomelic dwarfism, and suspected chondrodysplasia punctata. At birth, OI was suspected; however, a skeletal survey suggested ML II alpha/beta. Sequencing revealed compound heterozygosity for a reported pathogenic and novel but expected pathogenic GNPTAB variant. Molecular testing for autosomal recessive OI identified a SERPINF1 variant.

Similarity of geleophysic dysplasia and Weill-Marchesani syndrome.

The acromelic dysplasias comprise short stature, hands and feet, and stiff joints. Three disorders are ascribed to this group, namely Weill-Marchesani syndrome, geleophysic dysplasia, and acromicric dysplasia, although similar in phenotype, can be distinguished clinically. Weill-Marchesani syndrome, on the basis of microspherophakia and ectopia lentis; geleophysic dysplasia by progressive cardiac valvular thickening, tracheal stenosis, and/or bronchopulmonary insufficiency, often leading to early death. Microspherophakia has not been reported previously in geleophysic dysplasia. Mutations in FBN1, ADAMTS10, or ADAMTS17 cause Weill-Marchesani syndrome by disrupting the microfibrillar environment, while geleophysic dysplasia is associated with enhanced TGF-ß signaling mediated through mutations in FBN1 or ADAMTSL2. We studied a 35-year-old woman with geleophysic dysplasia, with short stature, small hands and feet, limitation of joint mobility, mild skin thickening, cardiac valvular disease, restrictive pulmonary disease, and microspherophakia. Sequencing of ADAMTSL2 demonstrated two changes: IVS8-2A>G consistent with a disease-causing mutation, and IVS14-7G>A with potential to generate a new splice acceptor site and result in aberrant mRNA processing. The unaffected mother carries only the IVS8-2A>G transition providing evidence that the two changes are in trans-configuration in our patient.

Ectopia lentis as the presenting and primary feature in Marfan syndrome.

Marfan syndrome (MFS) is a multisystem connective tissue disorder with primary involvement of the ocular, cardiovascular, and skeletal systems. We report on eight patients, all presenting initially with bilateral ectopia lentis (EL) during early childhood. These individuals did not have systemic manifestations of MFS, and did not fulfill the revised Ghent diagnostic criteria. However, all patients had demonstratable, disease-causing missense mutations in the FBN1 gene. Based on molecular results, cardiovascular imaging was recommended and led to the identification of mild aortic root changes in seven of the eight patients. The remaining patient had mitral valve prolapse with a normal appearing thoracic aorta. The findings presented in this paper validate the necessity of FBN1 gene testing in all individuals presenting with isolated EL. As we observed, these individuals are at increased risk of cardiovascular complications. Furthermore, we also noted that the majority of our patient cohort's mutations occurred in the 5' portion of the FBN1 gene, and were found to affect highly conserved cysteine residues, which may indicate a possible genotype-phenotype correlation. We conclude that in patients with isolated features of EL, FBN1 mutation analysis is necessary to aid in providing prompt diagnosis, and to identify patients at risk for potentially life-threatening complications. Additionally, knowledge of the type and location of an FBN1 mutation may be useful in providing further clinical correlation regarding phenotypic progression and appropriate medical management.

A loss of function mutation in the COL9A2 gene causes autosomal recessive Stickler syndrome.

Stickler syndrome is characterized by ocular, auditory, skeletal, and orofacial abnormalities. We describe a family with autosomal recessive Stickler syndrome. The main clinical findings consisted of high myopia, vitreoretinal degeneration, retinal detachment, hearing loss, and short stature. Affected family members were found to have a homozygous loss-of-function mutation in COL9A2, c.843_c.846 + 4del8. A family with autosomal recessive Stickler syndrome was previously described and found to have a homozygous loss-of-function mutation in COL9A1. COL9A1, COL9A2, and COL9A3 code for collagen IX. All three collagen IX α chains, α1, α2, and α3, are needed for formation of functional collagen IX molecule. In dogs, two causative loci have been identified in autosomal recessive oculoskeletal dysplasia. This dysplasia resembles Stickler syndrome. Recently, homozygous loss-of-function mutations in COL9A2 and COL9A3 were found to co-segregate with the loci. Together the data from the present study and the previous studies suggest that loss-of-function mutations in any of the collagen IX genes can cause autosomal recessive Stickler syndrome.

De novo ACTA2 mutation causes a novel syndrome of multisystemic smooth muscle dysfunction.

Smooth muscle cells (SMCs) contract to perform many physiological functions, including regulation of blood flow and pressure in arteries, contraction of the pupils, peristalsis of the gut, and voiding of the bladder. SMC lineage in these organs is characterized by cellular expression of the SMC isoform of α-actin, encoded by the ACTA2 gene. We report here on a unique and de novo mutation in ACTA2, R179H, that causes a syndrome characterized by dysfunction of SMCs throughout the body, leading to aortic and cerebrovascular disease, fixed dilated pupils, hypotonic bladder, malrotation, and hypoperistalsis of the gut and pulmonary hypertension.

Absence of TGFBR2 mutations in patients with spontaneous spinal CSF leaks and intracranial hypotension.

A heritable connective-tissue-disorder often is suspected in patients with spontaneous spinal CSF leaks and intracranial hypotension, but the nature of the disorder remains unknown in most patients. The aim of this study was to assess the gene encoding TGF-beta receptor-2 (TGFBR2) as a candidate gene for spinal CSF leaks. We searched the TGFBR2 gene for mutations in eight patients with spontaneous spinal CSF leaks who also had other features associated with TGFBR2 mutations, i.e., skeletal features of Marfan syndrome, arterial tortuosity, and(or) thoracic aortic aneurysm. The mean age of these 7 women and 1 man was 38 years (range 14-60 years). We detected no TGFBR2 mutations and conclude that TGFBR2 mutations are not a major factor in spontaneous spinal CSF leaks.

Consortium for osteogenesis imperfecta mutations in the helical domain of type I collagen: regions rich in lethal mutations align with collagen binding sites for integrins and proteoglycans.

Osteogenesis imperfecta (OI) is a generalized disorder of connective tissue characterized by fragile bones and easy susceptibility to fracture. Most cases of OI are caused by mutations in type I collagen. We have identified and assembled structural mutations in type I collagen genes (COL1A1 and COL1A2, encoding the proalpha1(I) and proalpha2(I) chains, respectively) that result in OI. Quantitative defects causing type I OI were not included. Of these 832 independent mutations, 682 result in substitution for glycine residues in the triple helical domain of the encoded protein and 150 alter splice sites. Distinct genotype-phenotype relationships emerge for each chain. One-third of the mutations that result in glycine substitutions in alpha1(I) are lethal, especially when the substituting residues are charged or have a branched side chain. Substitutions in the first 200 residues are nonlethal and have variable outcome thereafter, unrelated to folding or helix stability domains. Two exclusively lethal regions (helix positions 691-823 and 910-964) align with major ligand binding regions (MLBRs), suggesting crucial interactions of collagen monomers or fibrils with integrins, matrix metalloproteinases (MMPs), fibronectin, and cartilage oligomeric matrix protein (COMP). Mutations in COL1A2 are predominantly nonlethal (80%). Lethal substitutions are located in eight regularly spaced clusters along the chain, supporting a regional model. The lethal regions align with proteoglycan binding sites along the fibril, suggesting a role in fibril-matrix interactions. Recurrences at the same site in alpha2(I) are generally concordant for outcome, unlike alpha1(I). Splice site mutations comprise 20% of helical mutations identified in OI patients, and may lead to exon skipping, intron inclusion, or the activation of cryptic splice sites. Splice site mutations in COL1A1 are rarely lethal; they often lead to frameshifts and the mild type I phenotype. In alpha2(I), lethal exon skipping events are located in the carboxyl half of the chain. Our data on genotype-phenotype relationships indicate that the two collagen chains play very different roles in matrix integrity and that phenotype depends on intracellular and extracellular events.

Novel fibrillin 1 mutation in a case of neonatal Marfan syndrome: the increasing importance of early recognition.

Neonatal Marfan syndrome (MFS) is a severe form of classic MFS caused by mutations in a specific region of the fibrillin 1 gene (FBN1). We report a case of an infant with neonatal MFS who presented with flexion contractures in utero and severe skeletal and cardiovascular manifestations at birth. A novel de novo missense mutation in exon 26 of FBN1 was demonstrated. Because of potential new therapies, it is increasingly important to recognize neonatal MFS in utero as well as shortly after birth to initiate the appropriate diagnostic work-up and management.

A dominantly inherited spondylometaphyseal dysplasia with "corner fractures" and congenital scoliosis.

Spondylometaphyseal dysplasia (SMD) is a term applied to a varied group of skeletal dysplasias that principally involve the spine and the metaphyses of long bones. SMD Sutcliffe or "Corner Fracture" type is characterized by short stature, developmental coxa vara, fragmented appearance of the metaphyses ("corner fractures"), abnormally shaped vertebrae, odontoid hypoplasia, and dominant inheritance. We report a family with a dominantly inherited SMD with "corner fractures" and severe, congenital scoliosis but neither coxa vara nor odontoid abnormalities. This could either represent phenotypic variability in SMD-"Corner Fracture" type, or be a new, dominantly inherited SMD. The presence of severe, congenital scoliosis and short stature is present in all members of this family, and not typically seen in SMD-"Corner Fracture" type, supporting our hypothesis that this might represent a new, dominantly inherited SMD.

Lack of correlation between the type of COL1A1 or COL1A2 mutation and hearing loss in osteogenesis imperfecta patients.

Osteogenesis imperfecta (OI) is caused by mutations in COL1A1 and COL1A2 that code for the alpha1 and alpha2 chains of type I collagen. Phenotypes correlate with the mutation types in that COL1A1 null mutations lead to OI type I, and structural mutations in alpha1(I) or alpha2(I) lead to more severe OI types (II-IV). However, correlative analysis between mutation types and OI associated hearing loss has not been previously performed. A total of 54 Finnish OI patients with previously diagnosed hearing loss or age 35 or more years were analyzed here for mutations in COL1A1 or COL1A2. Altogether 49 mutations were identified, of which 41 were novel. The 49 mutations represented the molecular genetic background of 41.1% of the Finnish OI population. A total of 38 mutations were in COL1A1 and 11 were in COL1A2. Of these, 16 were glycine substitutions and 16 were splicing mutations in alpha1(I) or alpha2(I). In addition, 17 null allele mutations were detected in COL1A1. A total of 32 patients (65.3%) with a mutation had hearing loss. That is slightly more than in our previous population study on Finnish adults with OI (57.9%). The association between the mutation types and OI type was statistically evident. Patients with COL1A1 mutations more frequently had blue scleras than those with COL1A2 mutations. In addition, patients with COL1A2 mutations tended to be shorter than those with COL1A1 mutations. However, no correlation was found between the mutated gene or mutation type and hearing pattern. These results suggest that the basis of hearing loss in OI is complex, and it is a result of multifactorial, still unknown genetic effects.

Update of the UMD-FBN1 mutation database and creation of an FBN1 polymorphism database.

Fibrillin is the major component of extracellular microfibrils. Mutations in the fibrillin gene on chromosome 15 (FBN1) were first described in the heritable connective disorder, Marfan syndrome (MFS). FBN1 has also been shown to harbor mutations related to a spectrum of conditions phenotypically related to MFS, called "type-1 fibrillinopathies." In 1995, in an effort to standardize the information regarding these mutations and to facilitate their mutational analysis and identification of structure/function and phenotype/genotype relationships, we created a human FBN1 mutation database, UMD-FBN1. This database gives access to a software package that provides specific routines and optimized multicriteria research and sorting tools. For each mutation, information is provided at the gene, protein, and clinical levels. This tool is now a worldwide reference and is frequently used by teams working in the field; more than 220,000 interrogations have been made to it since January 1998. The database has recently been modified to follow the guidelines on mutation databases of the HUGO Mutation Database Initiative (MDI) and the Human Genome Variation Society (HGVS), including their approved mutation nomenclature. The current update shows 559 entries, of which 421 are novel. UMD-FBN1 is accessible at www.umd.be/. We have also recently developed a FBN1 polymorphism database in order to facilitate diagnostics.