A newly recognized syndrome involving limbs, pelvis, and genital organs or a variant of Al-Awadi/Raas-Rothschild syndrome?

We report on a 3-year-old Thai boy with limb, pelvic, and genital malformations. The combination of findings found in this patient is similar to that of Al-Awadi/Raas-Rothchild syndrome (AARRS) or limb/pelvis hypoplasia/aplasia syndrome. The upper limbs are more severely affected than the lower ones. Unlike that of AARRS, the radial ray is more severely affected than the ulnar ray. The presence of humeroulnar synostosis and humero-ulnar-radial synostosis and the absence of a radius distinguishes it from AARRS. The similarities and dissimilarities between the features in the present patient and other limb-pelvic hypoplasia/aplasia syndromes are discussed. The findings in this group of patients appear to demonstrate limb-pelvis-genital organ developmental field defects.     

Oral manifestations of 17 patients affected with mucopolysaccharidosis type VI

Objective

To assess oral manifestations of 17 patients with mucopolysaccharidosis type VI (MPS VI) or Maroteaux-Lamy syndrome.

Methods

We performed comprehensive oral examinations in 17 patients with MPS VI. Panoramic radiographs was performed only in 14 patients. All patients were of Thai, Turkish, and Indian origins. Ten of 17 patients had enzyme replacement therapy (ERT) (Naglazyme). Most Turkish patients (10/11) were on ERT. The Thai and Indian patients have never had ERT.

Results

Oral and radiographic examinations showed that hypoplastic mandibular condyles (93.3 %), malposition of unerupted teeth (92.9 %), large dental follicles (92.3 %), anterior open bite (86.7 %), maxillary constriction (56.3 %), and taurodontism (53.8 %) were common among patients with MPS VI. Newly recognized oral findings found in our study included taurodontism, long tooth roots, abnormal frenum, missing teeth, supernumerary teeth, and microdontia. Two patients who started ERT prior to 3 years old did not develope anterior open bite and one of them had mildly affected mandibular condyles.

Conclusion

Our study provides the most comprehensive study of oral manifestations in patients with MPS VI. Receiving ERT at very young ages may lessen craniofacial malformations including hypoplasic mandibular condyles and anterior open bite. Oral manifestations can be used as diagnostic features for MPS VI prior to assessing leukocyte ARSB activity or urinary excretion of dermatan sulfate.     

Two novel EBP mutations in Conradi-Hünermann-Happle syndrome

Conradi-Hünermann-Happle syndrome, also known as chondrodysplasia punctata type 2 (CDPX2), is an X-linked dominant disorder characterized by skin defects, skeletal and ocular abnormalities. CDPX2 was shown to be caused by mutations in the gene encoding emopamil binding protein (EBP). At least 58 different mutations have been described. Here we present clinical and molecular findings in two unrelated Thai girls with CDPX2. Mutation analysis by PCR-sequencing the entire coding region of EBP successfully revealed two potentially pathogenic, novel mutations, c.616G-->T and c.382delC. This study has expanded the spectrum of the EBP gene mutations causing CDPX2.     

GARS‐related disease in infantile spinal muscular atrophy: Implications for diagnosis and treatment

The majority of patients with spinal muscular atrophy (SMA) identified to date harbor a biallelic exonic deletion of SMN1. However, there have been reports of SMA‐like disorders that are independent of SMN1, including those due to pathogenic variants in the glycyl‐tRNA synthetase gene (GARS1). We report three unrelated patients with de novo variants in GARS1 that are associated with infantile‐onset SMA (iSMA). Patients were ascertained during inpatient hospital evaluations for complications of neuropathy. Evaluations were completed as indicated for clinical care and management and informed consent for publication was obtained. One newly identified, disease‐associated GARS1 variant, identified in two out of three patients, was analyzed by functional studies in yeast complementation assays. Genomic analyses by exome and/or gene panel and SMN1 copy number analysis of three patients identified two previously undescribed de novo missense variants in GARS1 and excluded SMN1 as the causative gene. Functional studies in yeast revealed that one of the de novo GARS1 variants results in a loss‐of‐function effect, consistent with other pathogenic GARS1 alleles. In sum, the patients' clinical presentation, assessments of previously identified GARS1 variants and functional assays in yeast suggest that the GARS1 variants described here cause iSMA. GARS1 variants have been previously associated with Charcot–Marie–Tooth disease (CMT2D) and distal SMA type V (dSMAV). Our findings expand the allelic heterogeneity of GARS‐associated disease and support that severe early‐onset SMA can be caused by variants in this gene. Distinguishing the SMA phenotype caused by SMN1 variants from that due to pathogenic variants in other genes such as GARS1 significantly alters approaches to treatment.     

The smallest teeth in the world are caused by mutations in the PCNT gene

We report a follow up study on two MOPD II Thai families with severe dental anomalies and hypoplastic alveolar bone. Striking dental anomalies comprise severe microdontia, opalescent and abnormally shaped teeth, and rootless molars. As a result of severe hypoplastic alveolar bone, most permanent teeth have been lost. Mutation analysis of PCNT revealed 2 novel mutations (p.Lys3154del and p.Glu1154X) and a recurrent mutation (p.Pro1923X). Teeth of the patient who carried a homozygous novel mutation of p.Glu1154X are probably the smallest ever reported. The sizes of the mandibular permanent incisors and all premolars were approximately 2-2.5 mm, mesiodistally. All previously reported, PCNT mutations have been described to cause premature truncation of the pericentrin protein. p.Lys3154del mutation was unique as it was pathogenic as a result of missing only a single amino acid. In situ hybridization of Pcnt shows its expression in the epithelium and mesenchyme during early stages of rodent tooth development. It is evident that PCNT has crucial role in tooth development. The permanent dentition is more severely affected than the one. This implies that PCNT appears to have more role in the development of the permanent dentition. As pericentrin is a critical centrosomal protein, the dental phenotype found in MOPD II patients is postulated to be the consequence of loss of microtubule integrity which leads to defective centrosome function.     

Mucopolysaccharidosis IVA (Morquio A syndrome) and VI (Maroteaux–Lamy syndrome): under-recognized and challenging to diagnose

Objective

Mucopolysaccharidosis IVA (MPS IVA, or Morquio A syndrome) and VI (MPS VI, or Maroteaux–Lamy syndrome) are autosomal recessive lysosomal storage disorders. Skeletal abnormalities are common initial presenting symptoms and, when recognized early, may facilitate timely diagnosis and intervention, leading to improved patient outcomes. Patients with slowly progressing disease and nonclassic phenotypes can be particularly challenging to diagnose. The objective was to describe the radiographic features of patients with a delayed diagnosis of MPS IVA or VI.

Materials and Methods

This was a retrospective study. The records of 5 MPS IVA and 3 MPS VI patients with delayed diagnosis were reviewed. Radiographs were evaluated by a radiologist with special expertise in skeletal dysplasias.

Results

An important common theme in these cases was the appearance of multiple epiphyseal dysplasia (MED) with epiphyseal changes seemingly confined to the capital (proximal) femoral epiphyses. Very few patients had the skeletal features of classical dysostosis multiplex.

Conclusions

Radiologists should appreciate the wide phenotypic variability of MPS IVA and VI. The cases presented here illustrate the importance of considering MPS in the differential diagnosis of certain skeletal dysplasias/disorders, including MED, some forms of spondylo-epiphyseal dysplasia (SED), and bilateral Perthes-like disease. It is important to combine radiographic findings with clinical information to facilitate early testing and accurate diagnosis.