Mutations in the RNA granule component TDRD7 cause cataract and glaucoma

The precise transcriptional regulation of gene expression is essential for vertebrate development, but the role of posttranscriptional regulatory mechanisms is less clear. Cytoplasmic RNA granules (RGs) function in the posttranscriptional control of gene expression, but the extent of RG involvement in organogenesis is unknown. We describe two human cases of pediatric cataract with loss-of-function mutations in TDRD7 and demonstrate that Tdrd7 nullizygosity in mouse causes cataracts, as well as glaucoma and an arrest in spermatogenesis. TDRD7 is a Tudor domain RNA binding protein that is expressed in lens fiber cells in distinct TDRD7-RGs that interact with STAU1-ribonucleoproteins (RNPs). TDRD7 coimmunoprecipitates with specific lens messenger RNAs (mRNAs) and is required for the posttranscriptional control of mRNAs that are critical to normal lens development and to RG function. These findings demonstrate a role for RGs in vertebrate organogenesis.

The stability of the diagnosis of developmental disability between ages 2 and 8 in a geographic cohort of very preterm children born in 1997

OBJECTIVE

Studies reporting the developmental outcomes for very preterm (VPT) children often focus on development at age 2 years. The aim of this study was to assess the stability of the rates of diagnosis of developmental disability from age 2 to 8 years in a regional cohort of VPT and extremely low-birth weight (ELBW) children and compare these with term controls.

METHODS

VPT (22-27 completed weeks of gestation) and ELBW (birth weight 500-999 g) children and matched term controls born in Victoria, Australia, in 1997 were enrolled at birth in a regional prospective longitudinal study. Outcomes were assessed at ages 2 and 8 years.

RESULTS

Of the 283 VPT/ELBW live births, 71% survived to age 8 years and 94% were assessed. Of the 199 controls, 100% survived to age 8 years and 86.9% were assessed. At age 2 years, the rates of nil, mild, moderate and severe disabilities in the VPT/ELBW children were respectively 51.9%, 20.9%, 13.4% and 13.9%; and at age 8 years, 43.9%, 36.9%, 10.7% and 8.6%. The Cohen κ statistic revealed poor agreement between disability status at ages 2 and 8 years for VPT/ELBW children (0.20, p<0.001) but a higher level of agreement (0.37, p<0.001) for the control children. This was primarily driven by differences in classification of cognitive disability between ages 2 and 8 years.

CONCLUSIONS

Developmental outcomes at age 2 years are only a moderate predictor of long-term outcome and are not a reliable end point for follow-up studies of VPT and ELBW children.

Van der Woude syndrome: dentofacial features and implications for clinical practice

BACKGROUND

Van der Woude syndrome (VWS) is the most common clefting syndrome in humans. It is characterized by the association of congenital lower lip fistulae with cleft lip and/or cleft palate. VWS individuals have a high prevalence of hypodontia. Although caused by a single gene mutation, VWS has variable phenotypic expression. This study aimed to describe the range of clinical presentations in 22 individuals with VWS to facilitate its diagnosis.

METHODS

A retrospective study of 22 patients with a diagnosis of VWS was undertaken at the Australian Craniofacial Unit (ACFU) in Adelaide. Three extended families with affected members were included in the study cohort.

RESULTS

The overall prevalence of lip pits in this study cohort was 86%. Cleft phenotypes included bilateral cleft lip and palate (32%); unilateral cleft lip and palate (32%); submucous cleft palate (23%); and isolated cleft hard and soft palate (9%). Missing permanent teeth were reported in 86% of affected individuals.

CONCLUSIONS

Submucous cleft palate in VWS may go undiagnosed if the lower lip pits are not detected. Associated hypodontia and resultant malocclusions will also require management by a dental team.

Changes in neurodevelopmental outcome at age eight in geographic cohorts of children born at 22-27 weeks' gestational age during the 1990s

BACKGROUND

The survival rate for children born with gestational ages 22-27 weeks is increasing, and this may be associated with higher rates of disability. The aims of this study were to determine the outcomes at age eight for a regional cohort of children born at 22-27 weeks during 1997, and to compare their rates of disability with a cohort of the same gestational age born in 1991-1992.

METHODS

Consecutive children with gestational ages in the range 22-27 weeks born in the state of Victoria, Australia, in 1997 and matched term controls were assessed at 8 years. Outcomes included blindness, deafness, cerebral palsy (CP) and intellectual impairment and disabilities caused by these impairments. These outcomes were compared with a cohort of 22-27-week and term children born in 1991-1992 in the same region.

RESULTS

Follow-up rates for the 1997 cohort at 8 years of age were 95% (144/151) for 22-27 weeks survivors and 89% (173/195) for controls. Rates of disability were substantially higher in the preterm cohort than the controls. The 1997 and 1991-1992 preterm cohorts had similar rates of moderate or severe disability (19%), however the rate of mild impairment was greater in 1997 (40% vs 24%). Rates of disability were almost identical in control groups. Intellectual impairment and CP were the major reasons for the higher rates of disability.

CONCLUSIONS

The high prevalence of adverse neurodevelopmental outcome in children born at 22-27 weeks compared with term controls at school age persists, and may even be increasing over time.

Multi-step binding of ADAMTS-13 to von Willebrand factor

BACKGROUND

ADAMTS-13 proteolytic activity is controlled by the conformation of its substrate, von Willebrand factor (VWF), and changes in the secondary structure of VWF are essential for efficient cleavage. Substrate recognition is mediated through several non-catalytic domains in ADAMTS-13 distant from the active site.

OBJECTIVES

We hypothesized that not all binding sites for ADAMTS-13 in VWF are cryptic and analyzed binding of native VWF to ADAMTS-13.

METHODS

Immunoprecipiation of VWF-ADAMTS-13 complexes using anti-VWF antibodies and magnetic beads was used. Binding was assessed by Western blotting and immunosorbent assays.

RESULTS

Co-immunoprecipitation demonstrated that ADAMTS-13 binds to native multimeric VWF (K(d) of 79 +/- 11 nmol L(-1)) with no measurable proteolysis. Upon shear-induced unfolding of VWF, binding increased 3-fold and VWF was cleaved. Binding to native VWF was saturable, time dependent, reversible and did not vary with ionic strength (I of 50-200). Moreover, results with ADAMTS-13 deletion mutants indicated that binding to native VWF is mediated through domains distal to the ADAMTS-13 spacer, probably thrombospondin-1 repeats. Interestingly, this interaction occurs in normal human plasma with an ADAMTS-13 to VWF stoichiometry of 0.0040 +/- 0.0004 (mean +/- SEM, n = 10).

CONCLUSIONS

ADAMTS-13 binds to circulating VWF and may therefore be incorporated into a platelet-rich thrombus, where it can immediately cleave VWF that is unfolded by fluid shear stress.

Abnormal white matter signal on MR imaging is related to abnormal tissue microstructure

BACKGROUND AND PURPOSE

White matter signal-intensity abnormalities (WMSA) on MR imaging are related to adverse neurodevelopmental outcome in extremely preterm infants. Diffusion tensor imaging (DTI) may detect alterations in cerebral white matter microstructure and thus may help confirm the pathologic basis of WMSA. This study aimed to relate regional DTI measures with severity of WMSA in very preterm infants.

MATERIALS AND METHODS

One hundred eleven preterm infants (birth weight, <1250 g and/or gestational age, <30 weeks) were scanned at term-equivalent age (1.5T). WMSA were classified as normal, focal, or extensive. Apparent diffusion coefficient (ADC), fractional anisotropy (FA), axial (lambda1), and radial ([lambda2 + lambda3]/2) diffusivity were calculated in 12 regions of interest placed in the bilateral posterior limbs of the internal capsule, frontal (superior and inferior), sensorimotor, and occipital (superior and inferior) white matter regions. Data were compared by using 1-way analysis of variance, with a Bonferroni correction for multiple comparisons.

RESULTS

Thirty-nine infants had normal, 59 infants had focal, and 13 infants had extensive WMSA. Compared with infants with normal or focal WMSA, infants with extensive WMSA had significantly lower FA in the internal capsule (P < .001), right inferior frontal regions (P < .05), and right superior occipital regions (P = .01); and higher radial diffusivity in the right internal capsule (P = .005), bilateral sensorimotor (P < .05), and right superior occipital regions (P < .05). Compared with infants with normal WMSA, infants with extensive WMSA had significantly higher ADC in bilateral sensorimotor regions (P < .01) and right superior occipital regions (P = .01), and lower axial diffusivity in the bilateral sensorimotor regions (P < .05).

CONCLUSIONS

There are significant region-specific changes in ADC, FA, radial diffusivity, and axial diffusivity in preterm infants with extensive WMSA. Altered radial diffusivity was most prominent. This implies that disrupted premyelinating oligodendroglia is the major correlate with extensive WMSA rather than axonal pathology.