Echocardiography as a Simple Initial Tool to Assess Right Ventricular Dimensions in Patients with Repaired Tetralogy of Fallot before Undergoing Pulmonary Valve Replacement: Comparison with Cardiovascular Magnetic Resonance Imaging

Objective: Accurate assessment of the right ventricle (RV) is essential in patients with repaired tetralogy of Fallot (TOF). We proposed a simple echocardiographic method to assess the RV dimensions and evaluated the relationship between linear echocardiographic measures of the RV and RV volumes obtained by cardiovascular magnetic resonance imaging (CMR). Methods: A total of 45 patients (27.4 ± 11.2 years; 40% male) with repaired TOF underwent CMR and echocardiography. Using echocardiography, RV dimensions were assessed from the parasternal short‐axis view using the longest RV internal diameter perpendicular to the mid‐interventricular septum. Significant RV dilatation was defined as an RV end‐diastolic volume index >160 mL/m² on CMR. Results: There were significant correlations between RV dimensions determined by echocardiography and the pulmonary regurgitation fraction, RV size, and function determined by CMR. The cutoff values of echocardiographic RV outflow tract (RVOT), end‐systolic and end‐diastolic dimension indices, and the combination of RVOT and end‐diastolic dimension indices to determine significant RV dilatation were 19.0, 19.4, 24.5, and 45.2 mm/m², respectively. The positive and negative predictive values for significant RV dilatation were 89.7% and 68.8% with RVOT diameter index ≥19.0 mm/m², 85.0% and 52.4% with RV end‐systolic dimension index ≥19.4 mm/m², 87.5% and 64.7% with RV end‐diastolic dimension index ≥24.5 mm/m², and 92.3% and 80.0% with the combination of RVOT and end‐diastolic dimension indices ≥45.2 mm/m², respectively. Conclusion: Echocardiography can be used to assess RV size in patients with repaired TOF with acceptable correlations with CMR as the reference standard.     

Organic acid disorders detected by urine organic acid analysis: twelve cases in Thailand over three-year experience

BACKGROUND: Disorders of organic acid (OA) metabolism are generally detected by qualitative analysis of urine organic acids by gas chromatography/mass spectrometry (GC/MS) which was well established in developed countries since 1980s. Confirmation of the diagnosis of organic acid disorders by OA analysis, enzyme analysis and molecular study is a difficult task in developing countries. METHODS: During 2001-2004, we had analysed 442 urine samples in 365 patients and identified 12 cases of organic acid disorders. RESULTS: We identified the following disorders: alkaptonuria (ALK)=1, isovaleric acidemia (IVA)=3, propionic acidemia (PA)=2, methylmalonic acidemia (MMA)=3, glutaric aciduria, type I (GA-I)=1, multiple carboxylase deficiency (MCD)=1, and glutaric acidemia, type II (GA-II)=1. CONCLUSIONS: OA disorders had never been diagnosed in Thailand before, until GC/MS technology was introduced to Thailand in 2001. Urine OA analysis also provided a diagnostic clue to other inborn errors of metabolism including amino acid disorders, urea cycle disorders, disorders of carbohydrate metabolism, and mitochondrial fatty acid oxidation disorders. Since then, we were able to diagnose numerous disorders, which led to prompt treatment and better outcome in our patients.     

High protein diet mimics hypertyrosinemia in newborn infants

Tyrosinemia resulting from administration of protein-dense infant diets was detected by newborn screening in two infants. Change of formula resulted in rapid resolution of the hypertyrosinemia. These cases identify nonstandard infant diets as a benign and reversible cause of tyrosinemia and a potential cause of positive newborn phenylketonuria screening.     

Mutation spectrum of and founder effects affecting the PTS gene in East Asian populations

The enzyme 6-pyruvoyl-tetrahydropterin synthase (PTPS, gene symbol: PTS) is involved in the second step of the de novo biosynthesis of tetrahydrobiopterin (BH4), which is a vital cofactor of nitric oxide synthases and three types of aromatic amino acid hydroxylases; the latter are important enzymes in the production of neurotransmitters. We conducted a study of PTS mutations in East Asia, including Taiwan, Mainland China, Japan, South Korea, the Philippines, Thailand and Malaysia. A total of 43 mutations were identified, comprising 22 previously reported mutations and 21 new discovered mutations. Among these, the c.155A>G, c.259C>T, c. 272A>G, c.286G>A and c.84-291A>G mutations were the most common PTS mutations in East Asia, while the c.58T>C and c.243G>A mutations were, respectively, specific to Filipinos and Japanese originating from Okinawa. Further studies demonstrated that each of the mutations listed above was in linkage disequilibrium to a specific allele of polymorphic microsatellite marker, D11S1347. These results suggest the presence of founder effects that have affected these frequent mutations in East Asia populations. In this context, D11S1347 should become one of the most reliable polymorphic markers for use in prenatal diagnosis among PTPS deficient families, especially where mutations are yet to be identified.     

Incidence and predisposing factors of anterior chamber gas bubbles during femtosecond laser flap creation

AIM: To investigate the incidence and the predisposing factors of anterior chamber (AC) gas bubbles during femtosecond laser (FS) flap creation for laser in situ keratomileusis (LASIK). METHODS: All patients who underwent FS-LASIK surgery at CMU LASIK Center between January 2013 and May 2016 were retrospective reviewed. Preoperative and intraoperative data including keratometry, white-to-white (WTW) corneal diameter, flap parameters (diameter, thickness, hinge position, and tunnel length) and pulse energy were reviewed and compared between incident group and control group. To determine the risk factors, univariate and multivariate conditional logistic regression were used; the eye was unit of analysis. RESULTS: The incidence of AC gas bubbles was 1.6% (22 out of 1378 eyes). The median WTW in the AC bubbles group was 11.5 mm (range 11.1-12.1), which was significantly different from the control group (11.7 mm, range 10.5-12.8, P=0.021). The result of the median WTW minus the flap diameter in the AC bubbles group was 2.5 mm (range 2.1-3.2), which was statistically different to the control group (2.7 mm, range 1.5-3.8, P=0.008). The logistic regression analysis showed that the result of the WTW minus the flap diameter in the AC bubbles group had an adjusted odds ratio of 0.204 (95%CI; 0.056-0.747, P=0.016). CONCLUSION: Development of AC gas bubbles during FS flap creation is not an uncommon event in Asian eyes which typically have a small WTW. The flap diameter when adjusted relatively to the WTW is a predisposing factor to the possibility of AC gas bubbles occurrence.     

Oral manifestations in patients and dogs with mucopolysaccharidosis Type VII

Mucopolysaccharidosis Type VII (MPS7, also called β‐glucuronidase deficiency or Sly syndrome; MIM 253220) is an extremely rare autosomal recessive lysosomal storage disease, caused by mutations in the GUSB gene. β‐glucuronidase (GUSB) is a lysosomal hydrolase involved in the stepwise degradation of glucuronic acid‐containing glycosaminoglycans (GAGs). Patients affected with MPS VII are not able to completely degrade glucuronic acid‐containing GAGs, including chondroitin 4‐sulfate, chondroitin 6‐sulfate, dermatan sulfate, and heparan sulfate. The accumulation of these GAGs in lysosomes of various tissues leads to cellular and organ dysfunctions. Characteristic features of MPS VII include short stature, macrocephaly, hirsutism, coarse facies, hearing loss, cloudy cornea, short neck, valvular cardiac defects, hepatosplenomegaly, and dysostosis multiplex. Oral manifestations in patients affected with MPS VII have never been reported. Oral manifestations observed in three patients consist of wide root canal spaces, taurodontism, hyperplastic dental follicles, malposition of unerupted permanent molars, and failure of tooth eruption with malformed roots. The unusual skeletal features of the patients include maxillary hypoplasia, hypoplastic midface, long mandibular length, mandibular prognathism, hypoplastic and aplastic mandibular condyles, absence of the dens of the second cervical vertebra, and erosion of the cortex of the lower border of mandibles. Dogs affected with MPS VII had anterior and posterior open bite, maxillary hypoplasia, premolar crowding, and mandibular prognathism. Unlike patients with MPS VII, the dogs had unremarkable mandibular condyles. This is the first report of oral manifestations in patients affected with MPS VII.