The Undiagnosed Diseases Network International: Five years and more!

Undiagnosed rare diseases (URDs) account for a significant portion of the overall rare disease burden, depending upon the country. Hence, URDs represent an unmet medical need. A specific challenge posed by the ensemble of the URD patient cohort is the heterogeneity of its composition; the group, indeed, includes very rare, still unidentified conditions as well as clinical variants of recognized rare diseases. Exact disease recognition requires new approaches that cut across national and institutional boundaries, may need the implementation of methods new to diagnostics, and embrace clinical care and research. To address these issues, the Undiagnosed Diseases Network International (UDNI) was established in 2014, with the major aims of providing diagnoses to patients, implementing additional diagnostic tools, and fostering research on novel diseases, their mechanisms, and their pathways. The UDNI involves centres with internationally recognized expertise, and its scientific resources and know-how aim to fill the knowledge gaps that impede diagnosis, in particularly for ultra-rare diseases. Consequently, the UDNI fosters the translation of research into medical practice, aided by active patient involvement. The goals of the UDNI are to work collaboratively and at an international scale to: 1) provide diagnoses for individuals who have conditions that have eluded diagnosis by clinical experts; 2) gain insights into the etiology and pathogenesis of novel diseases; 3) contribute to standards of diagnosing unsolved patients; and 4) share the results of UDNI research in a timely manner and as broadly as possible.

Effect of habitual exercise on urinary liver-type fatty acid-binding protein levels in middle-aged and older adults.

The purpose of this study was to examine the effect of habitual exercise on urinary liver-type fatty acid-binding protein (L-FABP), which can reflect the degree of various stresses on renal proximal tubule related to the progression of renal disease, in middle-aged and older adults. Cross-sectional and interventional approaches were used to comprehensively achieve this purpose. In the cross-sectional study, we investigated the relationship between physical activity levels and urinary L-FABP levels in 130 middle-aged and older adults. In the interventional study, subjects (n=31) were divided into two groups: exercise (n=19) and control group (n=12), whereby we examined the effects of 12-week aerobic exercise training on urinary L-FABP levels. The cross-sectional study showed that the urinary L-FABP levels were significantly lower in the higher physical activity group than in the lower physical activity group (P<.05). In the interventional study, 12-week aerobic exercise training significantly decreased urinary L-FABP levels (P<.01). Furthermore, the relative changes in urinary L-FABP levels were significantly correlated with the relative changes in physical activity levels and mean arterial pressure after intervention (r=-.374 and r=.530, respectively). Our results revealed that the urinary L-FABP levels were lower in the higher physical activity individuals, and aerobic exercise training decreased urinary L-FABP levels. These results suggest that habitual exercise appears to be associated with a decrease in the degree of several stresses on renal proximal tubule and to be beneficial for kidney health in middle-aged and older adults.

Effects of Aerobic and Resistance Training Combined with Fortified Milk on Muscle Mass, Muscle Strength, and Physical Performance in Older Adults: A Randomized Controlled Trial.

OBJECTIVES: Fortified milk and resistance training (RT) increase muscle mass, muscle strength, and physical performance in older adults, but it remains unclear whether RT combined with aerobic training (AT) would have stronger effects on these outcomes. The purpose of this study was to examine the effects of aerobic and resistance training (ART) combined with fortified milk consumption on muscle mass, muscle strength, and physical performance in older adults. DESIGN: Open-labeled randomized controlled trial. SETTING: University of Tsukuba. PARTICIPANTS: Fifty-six older adults aged 65-79. INTERVENTION: Participants were randomly allocated into resistance training (RT + fortified milk, n = 28) and aerobic and resistance training (ART + fortified milk, n = 28) groups. All participants attended supervised exercise programs twice a week at University of Tsukuba and ingested fortified milk every day for 12 weeks. Skeletal muscle index ([SMI]: appendicular lean mass/height2) was assessed using dual-energy X-ray absorptiometry as a muscle mass measure. One-repetition maximum strength was measured using four kinds of resistance training machines (chest press, leg extension, leg curl, and leg press) as muscle strength measures. Sit-to-stand and arm curl tests were also assessed as physical performance measures. MEASUREMENTS: The primary measurements were muscle mass and strength. The secondary outcomes were physical performance, blood samples, habitual diet, habitual physical activity, and medication use. RESULTS: Although the muscle strength and physical performance measures significantly improved in both groups, SMI significantly improved in only the RT group. There was no significant difference in the change in SMI and muscle strength measures between the two groups. However, the change in sit-to-stand and arm curl measures in the ART group were significantly higher than those in the RT group. CONCLUSIONS: These results suggest that AT before RT combined with fortified milk consumption has similar effects on skeletal muscle mass and strength compared with RT alone, but it may be a more useful strategy to improve physical performance in older adults. Although the mechanism of our intervention is uncertain, our program would be an effective prevention for sarcopenia in older adults.

Targeted next-generation sequencing in the diagnosis of neurodevelopmental disorders.

We developed a next-generation sequencing (NGS) based mutation screening strategy for neurodevelopmental diseases. Using this system, we screened 284 genes in 40 patients. Several novel mutations were discovered. Patient 1 had a novel mutation in ACTB. Her dysmorphic feature was mild for Baraitser-Winter syndrome. Patient 2 had a truncating mutation of DYRK1A. She lacked microcephaly, which was previously assumed to be a constant feature of DYRK1A loss of function. Patient 3 had a novel mutation in GABRD gene. She showed Rett syndrome like features. Patient 4 was diagnosed with Noonan syndrome with PTPN11 mutation. He showed complete agenesis of corpus callosum. We have discussed these novel findings.

Maternal uniparental isodisomy and heterodisomy on chromosome 6 encompassing a CUL7 gene mutation causing 3M syndrome.

We report a case of segmental uniparental maternal hetero- and isodisomy involving the whole of chromosome 6 (mat-hUPD6 and mat-iUPD6) and a cullin 7 (CUL7) gene mutation in a Japanese patient with 3M syndrome. 3M syndrome is a rare autosomal recessive disorder characterized by severe pre- and postnatal growth retardation that was recently reported to involve mutations in the CUL7 or obscurin-like 1 (OBSL1) genes. We encountered a patient with severe growth retardation, an inverted triangular gloomy face, an inverted triangle-shaped head, slender long bones, inguinal hernia, hydrocele testis, mild ventricular enlargement, and mild mental retardation. Sequence analysis of the CUL7 gene of the patient revealed a homozygous missense mutation, c.2975G>C. Genotype analysis using a single nucleotide polymorphism array revealed two mat-hUPD and two mat-iUPD regions involving the whole of chromosome 6 and encompassing CUL7. 3M syndrome caused by complete paternal iUPD of chromosome 6 involving a CUL7 mutation has been reported, but there have been no reports describing 3M syndrome with maternal UPD of chromosome 6. Our results represent a combination of iUPDs and hUPDs from maternal chromosome 6 involving a CUL7 mutation causing 3M syndrome.

Severe Developmental Delay in a Patient with 7p21.1-p14.3 Microdeletion Spanning the TWIST Gene and the HOXA Gene Cluster.

We describe a patient with a rare interstitial deletion of chromosome 7p21.1-p14.3 detected by array-CGH. The deletion encompassed 74 genes and caused haploinsufficiency (or loss of allele) of 6 genes known to be implicated in different autosomal dominant genetic disorders: TWIST, DFNA5, CYCS, HOXA11, HOXA13, and GARS. The patient had several morphological abnormalities similar to Saethre-Chotzen syndrome (caused by TWIST mutations) including craniosynostosis of the coronal suture and anomalies similar to those seen in hand-foot-uterus syndrome (caused by HOXA13 mutations) including hypospadias. The combined phenotype of Saethre-Chotzen syndrome and hand-foot-uterus syndrome of our patient closely resembles a previously reported case with a cytogenetically visible small deletion spanning 7p21-p14.3. We therefore conclude that microdeletions of 7p spanning the TWIST gene and HOXA gene cluster lead to a clinically recognizable 'haploinsufficiency syndrome'.

Cri-du-Chat Syndrome Cytogenetically Cryptic Recombination Aneusomy of Chromosome 5: Implications in Recurrence Risk Estimation.

Cri-du-chat syndrome is caused by haploinsufficiency of the genes on the distal part of the short arm of chromosome 5, and characteristic features include microcephaly, developmental delays, and a distinctive high-pitched mewing cry. Most cri-du-chat syndrome cases result from a sporadic de novo deletion that is associated with a low recurrence risk. On rare occasions, however, cri-du-chat syndrome with 5p monosomy can be accompanied by 5q trisomy. This combination is virtually always associated with parental large pericentric inversions. Among previously reported cri-du-chat syndrome cases with 5p monosomy accompanied by 5q trisomy, the aneusomy of chromosome 5 in all but one case was cytogenetically visible using G-banding. When an accompanying 5q trisomy is detected, a significant recurrence risk is expected. We here report on a patient with cri-du-chat syndrome phenotype who initially exhibited a normal karyotype on G-banding but in whom molecular analysis using multiplex ligation-dependent probe amplification and array comparative genomic hybridization revealed a 5p deletion accompanied by a 5q duplication. Parental chromosomal testing led to the identification of a very large pericentric inversion, of which breakpoints resided at the terminal regions of 5p15.31 and 5q35.1. This information was vital for counseling the family regarding the significantly high recurrence risk.

Juvenile Muscular Atrophy of a Unilateral Upper Extremity (Hirayama Disease) in a Patient with CHARGE Syndrome.

CHARGE syndrome is an autosomal dominant congenital anomaly syndrome, and the causative gene is CHD7. We report a patient with a CHD7 mutation who presented with juvenile muscular atrophy of a unilateral upper extremity, a presumably heterogeneous condition that is also known as Hirayama disease. This association has not been previously described. Weakness and atrophy of the hands should be carefully examined in patients with CHARGE syndrome, since Hirayama disease might be a possible complication in adolescent patients with this syndrome.

Correlation between genotype and supernumerary tooth formation in cleidocranial dysplasia.

INTRODUCTION: Cleidocranial dysplasia (CCD, MIM#119600), for which the responsible gene is RUNX2, is a genetic disorder characterized by hypoplasia or aplasia of the clavicles, patent fontanelles, and a short stature. Supernumerary teeth and delayed eruption and impaction of permanent teeth are frequently associated with CCD. Our previous study reported wide intrafamilial variation in supernumerary tooth formation associated with a mutation in the RUNT-domain of RUNX2, suggesting a low correlation between the genotype and supernumerary tooth formation. To further clarify this point, a more precise evaluation was performed. DESIGN: Gene mutational analysis of nine Japanese individuals with CCD was performed. Dental and skeletal characteristics were examined based on patient examinations and radiographs. RESULTS: Four different gene mutations, including one novel mutation in RUNX2 gene (NM_001024630), were identified. Among them, four individuals had the R225Q mutation, three siblings had the P224S mutation, and the other two individuals had different frame-shift mutations. Wide variations in supernumerary tooth formation were observed in individuals with identical gene mutations, and discordance was seen between monozygotic twins. Asymmetric supernumerary tooth formation was noted in five out of the nine individuals. CONCLUSION: Individuals with identical gene mutations showed a wide variation in the supernumerary tooth formation. Not only the genotype but also environmental factors and a complex system including epigenetics and copy number variation might regulate supernumerary tooth formation in CCD.

Diversity of supernumerary tooth formation in siblings with cleidocranial dysplasia having identical mutation in RUNX2 : possible involvement of non-genetic or epigenetic regulation.

INTRODUCTION: Cleidocranial dysplasia (CCD, MIM #119600) is an autosomal-dominant disorder characterized by hypoplasia or aplasia of clavicles, patent fontanelles and short stature. The responsible gene has been identified as RUNX2. CCD is also accompanied by characteristic dental abnormalities, e.g. supernumerary teeth, delayed eruption and impaction of permanent teeth. Intrafamilial variations of skeletal abnormalities are reported but those of dental abnormalities are obscure. To clarify this point, a precise examination of the dental features of CCD siblings having identical mutation was performed. DESIGN: Gene mutational analysis of three Japanese CCD siblings and their father was performed. Skeletal and dental characteristics were examined by the inquiry and radiographs. RESULTS: Three siblings uniformly showed patent fontanelles and short stature. They and their father had a novel missense mutation in the RUNT-domain (P210S) of RUNX2. The siblings were completely discordant for the dental characteristics with the position and number of supernumerary teeth being completely different. The youngest, a 12-year-old boy, had six supernumerary teeth, which appeared symmetrically around the maxillary canines and mandibular premolars. The second, a 15-year-old girl, had four supernumerary teeth which appeared around the mandibular incisors. The oldest, a 17-year-old boy, had 11 supernumerary teeth, which were symmetrically around the mandibular lateral dentition and asymmetrically around the maxillary incisors and premolars. CONCLUSION: The present study suggests the involvement of non-genetic or epigenetic regulation in supernumerary tooth formation in CCD.

1173C>T polymorphism in VKORC1 modulates the required warfarin dose.

The response to warfarin is highly variable among individuals and such variability is likely to have some genetic basis. We evaluted the effect of VKORC1 polymorphisms on warfarin response among Japanese, taking advantage of its unique population structure in which CYP2C9 *2 and *3 alleles are relatively rare. Thirty-one patients (12-34 years old; median, 22) on warfarin were recruited from a pediatric cardiology clinic. Genotyping of the C>T polymorphism at position 1173 in intron 1 of VKORC1 revealed that 26 patients (84%) were T/T homozygotes at nucleotide 1173, whereas 5 (16%) were C/T heterozygotes. Complete linkage disequilibrium was observed between the 1173C > T polymorphism and another polymorphism, the 3730G > A, in the 3' untranslated region. The C/T heterozyogtes at the 1173C > T polymorphism tended to require more warfarin than the T/T homozygotes, when adjusted for international normalized ratio (p = 0.003). Both the 1173C > T polymorphism and the 3730G > A polymorphism are likely to be inert from a functional standpoint. Rather, based on the complete linkage disequilibrium between 1173C > T and 3730G > A polymorphisms, we suspect that the actual change that defines the relative resistance to warfarin may be present in the proximity of these two polymorphisms.

EYA1 mutation in a newborn female presenting with cardiofacial syndrome.

The combination of an asymmetric crying face and heart defect has been termed cardiofacial syndrome. This "syndrome" is etiologically heterogeneous and a subset of patients have 22q111.2 deletions. We present a female with Cayler's cardiofacial syndrome phenotype who had a frameshift mutation of the EYA1 gene. We conclude that EYA1 mutation represents a previously undescribed cause of cardiofacial syndrome.

Micropenis and the AR Gene: mutation and CAG repeat-length analysis.

Various mutations of the AR gene and expanded CAG repeats at exon 1 of that gene have been reported in patients with hypospadias or genital ambiguity. However, the role of the AR gene has not been systemically studied in those with isolated micropenis lacking hypospadias or genital ambiguity. We studied 64 Japanese boys with isolated micropenis (age, 0-14 yr; median, 7 yr), whose stretched penile lengths were between -2.5 and -2.0 SD (borderline micropenis) in 31 patients (age, 0-13 yr; median, 8 yr) and below -2.5 SD (definite micropenis) in 33 patients (age, 0-14 yr; median, 6 yr). Mutation analysis of the AR gene was performed for exons 1-8 and their flanking introns, except for the CAG and GGC repeat regions at exon 1, by denaturing HPLC and direct sequencing, identifying a substitution of cytosine to thymine at a position -3 in the 3' splice site of intron 1 in a patient with definite micropenis. CAG repeat length at exon 1 was determined by electrophoresis with internal size markers and direct sequencing, revealing no statistically significant difference in the distribution of CAG repeat lengths [median (range) and mean +/- SE: total patients with isolated micropenis, 24 (14-34) and 23.5 +/- 0.38; patients with borderline micropenis, 24 (15-29) and 23.5 +/- 0.53; patients with definite micropenis, 23 (14-34) and 23.5 +/- 0.56; and 100 control males, 23 (16-32) and 23.5 +/- 0.29] or in the frequency of long CAG repeats (percentage of CAG repeats > or =26 and > or =28: total patients with isolated micropenis, 17.2 and 4.7%; patients with borderline micropenis, 19.4 and 6.5%; patients with definite micropenis, 15.2 and 3.0%; and 100 control males, 21.0 and 10.0%). These results suggest that an AR gene mutation is rare and that CAG repeat length is not expanded in children with isolated micropenis.