Quantitative DNA Methylation Analysis and Epigenotype-Phenotype Correlations in Taiwanese Patients with Silver-Russell Syndrome

Background: Silver-Russell syndrome (SRS; OMIM #180860) is a clinically and genetically heterogeneous imprinting disorder characterized by prenatal and postnatal growth failure. The aim of this study was to identify the epigenotype-phenotype correlations in these patients using quantitative DNA methylation analysis. Methods: One hundred and eighty-three subjects clinically suspected of having SRS were referred for diagnostic testing by the methylation profiling of H19-associated imprinting center (IC) 1 and imprinted PEG1/MEST regions using methylation-specific high-resolution melting analysis and methylation quantification with the MassARRAY assay. Correlations between quantitative DNA methylation status and clinical manifestations of the subjects according to the Netchine-Harbison (N-H) clinical scoring system for SRS were analyzed. Results: Among the 183 subjects, 90 had a clinical diagnosis of SRS [N-H score ≥ 4 (maximum = 6)] and 93 had an SRS score < 4. Molecular lesions were detected in 41% (37/90) of the subjects with a clinical diagnosis of SRS, compared with 3% (3/93) of those with an N-H score < 4. The IC1 methylation level was negatively correlated with the N-H score. The molecular diagnosis rate was positively correlated with the N-H score. Thirty-one subjects had IC1 hypomethylation (IC1 methylation level <35% by the MassARRAY assay), seven had maternal uniparental disomy 7, and two had pathogenic copy number variants. Among the 90 subjects with an N-H score ≥ 4, the IC1 methylation level was significantly different between those with or without some clinical SRS features, including birth length ≤ 10th centile, relative macrocephaly at birth, normal cognitive development, body asymmetry, clinodactyly of the fifth finger, and genital abnormalities. Conclusions: This study confirmed the suitability of the N-H clinical scoring system as clinical diagnostic criteria for SRS. Quantitative DNA methylation analysis using the MassARRAY assay can improve the detection of epigenotype-phenotype correlations, further promoting better genetic counseling and multidisciplinary management for these patients.

Scoliosis and BMI in patients with Prader-Willi syndrome

Although scoliosis is commonly seen in patients with Prader-Willi syndrome, the patterns and extent of the deformity may change along their growth. Increased body weight is another issue in these patients, and its relationship with scoliosis is still controversial. The aim of this study was to evaluate scoliosis in patients with PWS, and its relationship with BMI. This was a retrospective cohort study in which a series of radiographic images and BMI from each patient were collected, and the data were rearranged following the age at which they were recorded. These patients were subsequently labeled as non-Scoliotic (<10°), Moderate (10° - 39°), and Severe (≥40°) according to their final Cobb angle, also as Normal (≤85%), Overweight (86%-95%), and Obese (≥95%) according to final BMI percentage. Thirty-four patients with age from 1 to 20 years old were recruited for this study, and the mean length of follow-up was 6.6 years. The prevalence of scoliosis was 71% (24 patients in Moderate, and 9 patients in Severe), and 65.6% were either overweight (11 patients) or obese (10 patients). The mean BMI percentage in non-scoliotic patients was 93.10 ± 13.84, which was significantly higher than that of the scoliotic groups ( P  = 0.0180). When looking at the longitudinal change, the non-Scoliotic group had high BMI since childhood, and obese patients had less spine deformity also from early childhood. In this study, we found that the prevalence of scoliosis in Taiwanese population with PWS was 71% without gender preference. Not every patient had a high BMI, and obese patients seemed to have significantly less chance to develop scoliosis. Level III.

Progression of Obstructive Sleep Apnea Syndrome in Pediatric Patients with Prader-Willi Syndrome

Obstructive sleep apnea syndrome (OSAS) is one of the most common comorbidities in patients with Prader-Willi syndrome (PWS) and causes significant consequences. This observational study was conducted to investigate the progression of OSAS in pediatric patients with PWS, who had not undergone upper airway surgery, through a longitudinal follow-up of their annual polysomnography results. Annual body mass index (BMI), BMI z-score, sleep efficiency and stages, central apnea index (CAI), obstructive apnea-hypopnea index (OAHI), and oxygen saturation nadir values were longitudinally analyzed. At enrollment, of 22 patients (10 boys and 12 girls) aged 11.7 ± 3.9 years, 20 had OSAS. During the 4-year follow-up, only two patients had a spontaneous resolution of OSAS. The average BMI and BMI z-score increased gradually, but CAI and OAHI showed no significant differences. After statistical adjustment for sex, age, genotype, growth hormone use, and BMI z-score, OAHI was associated with the BMI z-score and deletion genotype. In conclusion, OSAS is common in patients with PWS, and rarely resolved spontaneously. Watchful waiting may not be the best OSAS management strategy. Weight maintenance and careful selection of surgical candidates are important for OSAS treatment in patients with PWS.

Dynamic Changes in the Quantitative Electroencephalographic Spectrum During Attention Tasks in Patients With Prader–Willi Syndrome

Introduction: Attention problems are frequently observed in patients with Prader–Willi syndrome (PWS); however, only few studies have investigated the severity and mechanisms of attention problems in them. In this study, we aim to evaluate dynamic changes in the quantitative electroencephalographic (EEG) spectrum during attention tasks in patients with PWS.

Method: From January to June 2019, 10 patients with PWS and 10 age-matched neurotypical control participants were recruited at Taipei Tzu Chi Hospital. Each participant completed Conners’ continuous performance test, third edition (CPT-3), tasks with simultaneous EEG monitoring. The dynamic changes in the quantitative EEG spectrum between the resting state and during CPT-3 tasks were compared.

Results: Behaviorally, patients with PWS experienced significant attention problems, indicated by the high scores for several CPT-3 variables. The theta/beta ratio of the resting-state EEG spectrum revealed no significant differences between the control participants and patients with PWS. During CPT-3 tasks, a significant decrease in the alpha power was noted in controls compared with that in patients with PWS. The attention-to-resting alpha power ratio was positively correlated with many CPT-3 variables. After adjusting for genotype, age, intelligence, and body mass index, the attention-to-resting alpha power ratio was still significantly correlated with participants’ commission errors.

Conclusion: This study provides evidence that attention problems are frequently observed in patients with PWS, while attention impairment can be demonstrated by dynamic changes in the quantitative EEG spectrum.

Whole Exome Sequencing Identifies a Novel Homozygous Missense Mutation in the CSB Protein-Encoding ERCC6 Gene in a Taiwanese Boy with Cockayne Syndrome

Background: Cockayne syndrome (CS) is a rare form of dwarfism that is characterized by progressive premature aging. CS is typically caused by mutations in the excision repair cross-complementing protein group 6 (ERCC6) gene that encodes the CS group B (CSB) protein. Using whole exome sequencing, we recently identified a novel homozygous missense mutation (Leu536Trp) in CSB in a Taiwanese boy with CS. Since the current database (Varsome) interprets this variant as likely pathogenic, we utilized a bioinformatic tool to investigate the impact of Leu536Trp as well as two other variants (Arg453Ter, Asp532Gly) in similar articles on the CSB protein structure stability. Methods: We used iterative threading assembly refinement (I-TASSER) to generate a predictive 3D structure of CSB. We calculated the change of mutation energy after residues substitution on the protein stability using I-TASSER as well as the artificial intelligence program Alphafold. Results: The Asp532Gly variant destabilized both modeled structures, while the Leu536Trp variant showed no effect on I-TASSER’s model but destabilized the Alphafold’s modeled structure. Conclusions: We propose here the first case of CS associated with a novel homozygous missense mutation (Leu536Trp) in CSB. Furthermore, we suggest that the Asp532Gly and Leu536Trp variants are both pathogenic after bioinformatic analysis of protein stability.

High prevalence of lower urinary tract dysfunction in patients with Prader-Willi syndrome

AIMS

To report the first noninvasive urodynamic screening of lower urinary tract dysfunction (LUTD) in children, adolescents, and young adults with Prader-Willi Syndrome (PWS).

METHODS

We recruited 37 PWS patients with/without lower urinary tract symptoms (LUTS) from our hospital. Uroflowmetry was performed in 36 patients. In addition, 20 patients underwent postvoid residual urine (PVR) measurement by transabdominal ultrasound. LUTD is defined as abnormal uroflow patterns, low peak flow rate (Q_max ), or elevated PVR by age. Videourodynamic study (VUDS) was performed in selected cases.

RESULTS

Mean and median age of the patients were 17.7 ± 7.8 years and 16 years. Male to female ratio was 15/22. Two patients were excluded from the following analysis because of voided volume less than or equal to 50 ml. Of the remaining 34 uroflowmetry examination, normal voiding pattern (bell shape) was observed in 22 (64.7%) patients. Abnormal uroflowmetry pattern were obstructive in 6 (17.6%), staccato in 3 (8.8%), intermittent in 2 (5.8%), tower in 1 (2.9%), and plateau in 0 patients. Ten (29.4%) patients had a Q_max less than 15 ml/s. Of 20 patients undergoing PVR tests 10 (50%) had elevated PVR by age ( > 6% of estimated bladder volume). In all, 17/34 (50.0%) PWS patients had at least one abnormality of the noninvasive tests. Of the three cases undergoing VUDS all showed detrusor sphincter dyssynergia.

CONCLUSIONS

Half of PWS patients with/without LUTS had LUTD. Noninvasive study such as uroflowmetry and postvoid residual urine by ultrasound is recommended to all patients with PWS.

Parenting stress in families of children with Prader-Willi syndrome

Prader-Willi syndrome (PWS) is a neurodevelopmental disorder characterized by multiple endocrine, metabolic, respiratory, cognitive, and behavioral/psychiatric symptoms that may lead to severe emotional strain in their caregivers. In this study, we evaluated parenting stress by the Parenting Stress Index-short form (PSI/SF) and parent-reported behavioral symptoms by the Child Behavior Checklist (CBCL/6-18) in families of children with PWS. Sixty-seven home-resident PWS patients and their families were recruited in this study. The patients' mean age was 14.9 ± 8.3 years, and 33 (50.8%) were male. High parenting stress was reported by 41.5% families, as determined by high total stress scores of PSI/SF. The patients in high stress families were significantly older than those in low stress families (18.2 ± 8.0 vs. 12.6 ± 7.8 years, p = .007). CBCL/6-18 was used to evaluate the somatic and neuropsychiatric symptoms of PWS patients aged between 6 and 18 in the subgroup of the 35 families. In this subgroup, 37.1% of families reported high parenting stress. High stress families reported a higher T-score in anxiety/depression, withdrawn behavior, somatic complaints, thought problems, attention problems, and delinquent and aggressive behavior of their children with PWS. After multivariate stepwise logistic regression analysis, the T-score of somatic complaints was the only factor related to high parenting stress, with an odds ratio of 1.279. Our data demonstrated the high care burden of families with PWS and highlighted the importance of having dedicated medical care for both somatic and neuropsychiatric symptoms.

Firing activity of locus coeruleus noradrenergic neurons decreases in necdin-deficient mice, an animal model of Prader-Willi syndrome

BACKGROUND

Prader-Willi syndrome (PWS) is a neurodevelopmental disorder characterized by multiple respiratory, cognitive, endocrine, and behavioral symptoms, such as central apnea, intellectual disabilities, exaggerated stress responses, and temper tantrums. The locus coeruleus noradrenergic system (LC-NE) modulates a diverse range of behaviors, including arousal, learning, pain modulation, and stress-induced negative affective states, which are possibly correlated with the pathogenesis of PWS phenotypes. Therefore, we evaluated the LC-NE neuronal activity of necdin-deficient mice, an animal model of PWS.

METHODS

Heterozygous necdin-deficient mice (B6.Cg-Ndntm1ky) were bred from wild-type (WT) females to generate WT (+m/+p) and heterozygotes (+m/-p) animals, which were examined of LC-NE neuronal activity, developmental reflexes, and plethysmography.

RESULTS

On slice electrophysiology, LC-NE neurons of Ndntm1ky mice with necdin deficiency showed significantly decreased spontaneous activities and impaired excitability, which was mediated by enhanced A-type voltage-dependent potassium currents. Ndntm1ky mice also exhibited the neonatal phenotypes of PWS, such as hypotonia and blunt respiratory responses to hypercapnia.

CONCLUSIONS

LC-NE neuronal firing activity decreased in necdin-deficient mice, suggesting that LC, the primary source of norepinephrine in the central nervous system, is possibly involved in PWS pathogenesis.

Genetic Architecture Associated With Familial Short Stature

CONTEXT

Human height is an inheritable, polygenic trait under complex and multilocus genetic regulation. Familial short stature (FSS; also called genetic short stature) is the most common type of short stature and is insufficiently known.

OBJECTIVE

To investigate the FSS genetic profile and develop a polygenic risk predisposition score for FSS risk prediction.

DESIGN AND SETTING

The FSS participant group of Han Chinese ancestry was diagnosed by pediatric endocrinologists in Taiwan.

PATIENTS AND INTERVENTIONS

The genetic profiles of 1163 participants with FSS were identified by using a bootstrapping subsampling and genome-wide association studies (GWAS) method.

MAIN OUTCOME MEASURES

Genetic profile, polygenic risk predisposition score for risk prediction.

RESULTS

Ten novel genetic single nucleotide polymorphisms (SNPs) and 9 reported GWAS human height-related SNPs were identified for FSS risk. These 10 novel SNPs served as a polygenic risk predisposition score for FSS risk prediction (area under the curve: 0.940 in the testing group). This FSS polygenic risk predisposition score was also associated with the height reduction regression tendency in the general population.

CONCLUSION

A polygenic risk predisposition score composed of 10 genetic SNPs is useful for FSS risk prediction and the height reduction tendency. Thus, it might contribute to FSS risk in the Han Chinese population from Taiwan.

Clinical characteristics and epilepsy in genomic imprinting disorders: Angelman syndrome and Prader-Willi syndrome

Angelman syndrome (AS) and Prader–Willi syndrome (PWS) are considered sister imprinting disorders. Although both AS and PWS congenital neurodevelopmental disorders have chromosome 15q11.3-q13 dysfunction, their molecular mechanisms differ owing to genomic imprinting, which results in different parent-of-the-origin gene expressions. Recently, several randomized controlled trials have been proceeded to treat specific symptoms of AS and PWS. Due to the advance of clinical management, early diagnosis for patients with AS and PWS is important. PWS is induced by multiple paternal gene dysfunctions, including those in MKRN3, MAGEL2, NDN, SNURF-SNPRPN, NPAP1, and a cluster of small nucleolar RNA genes. PWS patients exhibit characteristic facial features, endocrinological, and behavioral phenotypes, including short and obese figures, hyperphagia, growth hormone deficiency, hypogonadism, autism, or obsessive– compulsive-like behaviors. In addition, hypotonia, poor feeding, failure to thrive, and typical facial features are major factors for early diagnosis of PWS. For PWS patients, epilepsy is not common and easy to treat. Conversely, AS is a single-gene disorder induced by ubiquitin-protein ligase E3A dysfunction, which only expresses from a maternal allele. AS patients develop epilepsy in their early lives and their seizures are difficult to control. The distinctive gait pattern, excessive laughter, and characteristic electroencephalography features, which contain anterior-dominated, high-voltage triphasic delta waves intermixed with epileptic spikes, result in early suspicion of AS. Often, polytherapy, including the combination of valproate, levetiracetam, lamotrigine, and benzodiazepines, is required for controlling seizures of AS patients. Notably, carbamazepine, oxcarbazepine, and vigabatrin should be avoided, since these may induce nonconvulsive status epilepticus. AS and PWS presented with distinct clinical manifestations according to specific molecular defects due to genomic imprinting. Early diagnosis and teamwork intervention, including geneticists, neurologists, rehabilitation physicians, and pulmonologists, are important. Epilepsy is common in patients with AS, and after proper treatment, seizures could be effectively controlled in late childhood or early adulthood for both AS and PWS patients.

Is prone sleeping dangerous for neonates? Polysomnographic characteristics and NDN gene analysis

Objective:

Prone sleep is an identified risk factor for sudden infant death syndrome, possibly due to reduced blood pressure, cerebral oxygenation, and impaired cerebral vascular control. Cardiac and respiratory responses in neonates during supine and prone sleep have not been reported.

Materials and Methods:

In this study, daytime polysomnography (PSG) data from 17 neonates aged 2–3 days during supine and prone sleep were reported and the NDN gene, an important gene for neonatal respiratory control, was sequenced for correlation with neonatal respiratory parameters. Heart rate (HR), oxygen saturation, carbon dioxide concentration, sleep stages, central apnea index (CAI), obstructive apnea/hypopnea index (OAHI), and oxygen nadir were compared between supine and prone sleep and between participants with different single-nucleotide polymorphisms (SNPs) in the NDN gene.

Results:

During prone sleep, neonates had a faster HR, decreased oxygen saturation, and a longer duration of oxygen saturation <90% than during supine sleep, suggesting that cardiopulmonary responsiveness was impaired. Sleep efficiency, sleep stages, oxygen nadir, and carbon dioxide tension were not different during supine and prone sleep. Central apnea occurred more significantly than obstructive apnea. During supine and prone sleep, the CAI was 3.3 ± 2.9/h and 2.3 ± 2.6/h and the OAHI was 0.6 ± 0.7/h and 0.6 ± 0.8/h, respectively. We found one SNP rs3743340 in the NDN gene that had no effect on the sleep and respiratory parameters of PSG.

Conclusion:

Tachycardia and respiratory instability were recorded in neonates during prone sleep, suggesting that neonates are vulnerable to cardiopulmonary events during prone sleep. Therefore, young neonates should be kept in the supine sleep position unless there are contraindications.

Functional independence of Taiwanese children with Prader-Willi syndrome

Prader-Willi syndrome (PWS) is a genetic disorder with obesity, developmental delay, short stature, and behavioral abnormalities. The study aimed to assess the functional independence in children with PWS. The Functional Independence Measure for Children (WeeFIM) was used to evaluate 81 children with PWS (44 boys and 37 girls) with a median age of 11 years 1 month (range 2 years 8 months to 20 years 2 months) were recruited between January 2013 and December 2016. The mean total WeeFIM score was 103.8 (maximum 126). Sixty-five patients (80%) had deletion type PWS, 16 (20.0%) had nondeletion type. The scores were 103.6 ± 18.5 for deletion and 104.8 ± 18.3 for nondeletion type (p = .405), 104.8 ± 19.3 in boys and 102.6 ± 17.3 in girls (p = .293). The mean self-care, mobility, and cognition scores were 47 (maximum 56), 33 (maximum 35), and 24 (maximum 35), respectively. All total scores and 18 subscores in the three functional domains were positively correlated with age (p < .05). Most children required assistance in problem-solving, comprehension, and expression. The WeeFIM identified the strengths and limitations of children with PWS and confirmed that support and supervision were needed in cognitive and self-care tasks.

Motor performance in Prader-Willi syndrome patients and its potential influence on caregiver's quality of life

Background

Prader-Willi syndrome (PWS) is a complex, multisystem genetic disorder characterized by a variety of physical, cognitive, and behavioral impairments. PWS is a unique sarcopenia model characterized by an abnormal increase in body fat mass and a decrease in muscle mass that predisposes patients to reduced physical activity, functional limitations, and disability. These manifestations may require both symptomatic and supportive management, thus negatively influencing their lifelong family caregiver’s quality of life. The aim of this study was to examine the functional motor performance of adults with PWS in Taiwan and to measure the quality of life of their primary family caregivers.

Methods

The functional motor tests consisted of the following: (1) 30-s sit-to-stand test, (2) timed up-and-go test, (3) hand grip and lateral pinch strength tests, and (4) Berg Balance Scale. The World Health Organization Quality of Life-short form (WHOQOL-BREF) and the Short-Form 36 Health Survey Questionnaire (SF-36) were used to evaluate health-related quality of life, and the parenting stress index was used to assess the magnitude of stress within the parent-child system.

Results

The participants included seven adults (two females and five males) with genetically confirmed PWS and their respective main caregivers. The mean age of the adults with PWS was 25.28 years; range 18–31 years, SD 5.10; the mean BMI was 29.2 kg/m², SD 6.43. All adults with PWS showed lower hand grip and lateral pinch strengths, fewer sit-to-stand cycles during the 30-s chair stand test, and greater average time during the timed up-and-go test when compared to the normative data on healthy adults. Balance was negatively correlated with the caregiver’s health concepts of social functioning (r_s −0.879, P = 0.009) and with role limitations due to physical problems (r_s −0.899, P = 0.006) and emotional problems (r_s −0.794, P = 0.033); hand grip strength was negatively correlated with bodily pain (r_s −0.800, P = 0.031), as assessed using the SF-36 questionnaire. The timed up-and-go test was positively correlated with the social relationship domain (r_s 0.831, P = 0.021), as assessed using the WHOQOL-BREF questionnaire. The parenting stress index showed no association with the PWS patient’s physical activities.

Conclusions

All adults with PWS showed decreased upper and lower limb strength and functional mobility when compared to healthy adults. Some of their motor performance might have negative effects on their primary family members in terms of social participation and physical and emotional role limitations. Future research should explore the relationship between physical performances, psychological difficulties of PWS and caregiver’s QOL.

Adolescent onset of vertically transmitted untreated AIDS: A report of one case

A 12-year-old adolescent girl with intractable pneumonia and desaturation was sent to our hospital. An immunocompromised state was highly suspected because of an oral thrush persisting for a year and pneumonia of unusual severity. Laboratory tests confirmed she had human immunodeficiency virus (HIV) infection and full-blown AIDS. She lived with her adopted parents and reported no history of sexual abuse, drug abuse, or blood transfusion. We contacted the Center of Disease Control and discovered that her mother had HIV and had passed away a few years ago, thus confirming that she was a case of vertically transmitted HIV patient who had only developed AIDS recently. Even though her mother had HIV, our public health department failed to follow her as a potential HIV victim, probably because routine HIV examinations for pregnant women only started in 2005, 4 years after she was born.

Association of human height-related genetic variants with familial short stature in Han Chinese in Taiwan

Human height can be described as a classical and inherited trait model. Genome-wide association studies (GWAS) have revealed susceptible loci and provided insights into the polygenic nature of human height. Familial short stature (FSS) represents a suitable trait for investigating short stature genetics because disease associations with short stature have been ruled out in this case. In addition, FSS is caused only by genetically inherited factors. In this study, we explored the correlations of FSS risk with the genetic loci associated with human height in previous GWAS, alone and cumulatively. We systematically evaluated 34 known human height single nucleotide polymorphisms (SNPs) in relation to FSS in the additive model (p < 0.00005). A cumulative effect was observed: the odds ratios gradually increased with increasing genetic risk score quartiles (p < 0.001; Cochran-Armitage trend test). Six affected genes-ZBTB38, ZNF638, LCORL, CABLES1, CDK10, and TSEN15-are located in the nucleus and have been implicated in embryonic, organismal, and tissue development. In conclusion, our study suggests that 13 human height GWAS-identified SNPs are associated with FSS risk both alone and cumulatively.

Elevated postvoid residual urine volume predicting recurrence of urinary tract infections in toilet-trained children

BACKGROUND

The aim of this study was to examine whether toilet-trained children with a history of febrile urinary tract infection (fUTI) and elevated postvoid residual (PVR) urine volume according to a recently published PVR nomogram were at greater risk of UTI recurrence.

MATERIALS AND METHODS

One month after recovery from febrile UTI, constipation was diagnosed according to the Rome III criteria, and lower urinary tract (LUT) function was evaluated with two sets of uroflowmetry and PVR by ultrasonography. For children aged ≦ 6 and ≧ 7 years, elevated PVR is defined as >20 and >10 ml, respectively. Cox proportion hazards regression was used to evaluate the risk factors for recurrence of UTI.

RESULTS

Between 2005 and 2011, 60 children aged 6.5 ± 2.5 years (boy:girl ratio 27:33) were enrolled for analysis. Univariate analysis showed that recurrent febrile UTI was more commonly observed in children with elevated PVR [repetitive elevated PVR: hazard ratio (HR) 5.75, 95% confidence interval (CI) 1.41-23.4; one elevated PVR: HR 4.53, 95% CI 1.01-20.2] and high-grade vesicoureteral reflux (VUR; HR 4.53, 95% CI 1.46-14.07). Multivariate analysis showed that younger age (HR 1.37, 95% CI 1.03-1.82, p < 0.01) and elevated PVR (HR 2.88, 95% CI 1.44-5.73, p = 0.01) were significant, independent risk factors for recurrent febrile UTI--but not gender, presence of high-grade VUR and constipation.

CONCLUSION

Elevated PVR defined by the new PVR nomogram predicted recurrent UTI in children with history of febrile UTI. Care should be taken to manage children with elevated PVR.

Pediatric round pneumonia

"Round pneumonia" or "spherical pneumonia" is a well-characterized clinical entity that seems to be less addressed by pediatricians in Taiwan. We herein report the case of a 7-year-old boy who presented with prolonged fever, cough, and chest X-rays showing a well-demarcated round mass measuring 5.9 × 5.6 × 4.3 cm in the left lower lung field, findings which were typical for round pneumonia. The urinary pneumococcal antigen test was positive, and serum anti-Mycoplasma pneumoniae antibody titer measurement using a microparticle agglutination method was 1:160 (+). After oral administration of antibiotics including azithromycin and amoxicillin/clavulanate, which was subsequently replaced by ceftibuten due to moderate diarrhea, the fever subsided 2 days later and the round patch had completely resolved on the 18th day after the diagnosis. Recent evidence suggests treating classical round pneumonia with antibiotics first and waiving unwarranted advanced imaging studies, while alternative etiologies such as abscesses, tuberculosis, nonbacterial infections, congenital malformations, or neoplasms should still be considered in patients with atypical features or poor treatment response.

Incidence of severe combined immunodeficiency through newborn screening in a Chinese population

BACKGROUND/PURPOSE

In order to know the true incidence of severe combined immunodeficiency (SCID) in a Chinese population, we conducted and implemented SCID newborn screening in Taiwan.

METHODS

Between May 1, 2010 and December 31, 2011, the National Taiwan University Hospital Newborn Screening Center screened all newborns for T-cell lymphopenia by measuring the copy number of T-cell receptor excision circles (TRECs) and RNase P. Newborns with low TREC values were subjected to complete blood cell counts and flow cytometry.

RESULTS

A total of 106,391 newborns were screened using the TREC assay over a period of 19 months. Five newborns were immediately referred for confirmatory tests, including two SCID patients and two patients with persistent T-cell lymphopenia; a third SCID patient was found 2 months after the study period. All three SCID cases received stem cell transplantation at the age of 2-5 months. We also identified five cases of 22q11.2 microdeletion syndrome. During this period, two SCID patients from among the unscreened newborns were reported, and they died at ages 3 months and 4 months, respectively.

CONCLUSION

Newborn screening to measure the number of TREC copies successfully identifies newborns with T-cell lymphopenia, 22q11.2 microdeletion syndrome, and other high-risk conditions. Taken together, the incidence of T-cell lymphopenia in apparently healthy newborns is more than 1 in 11,821, and further attention to their immune functions is warranted.

Analysis of CYP21A1P and the duplicated CYP21A2 genes

The RCCX module on chromosome 6p21.3 has 3 possible forms: monomodular, bimodular, and trimodular. Chromosomes with 4 RCCX modules are very rare. In the monomodule, most of the CYP21A1P genes do not exist. However, haplotypes of the RCCX module with more than one CYP21A2 gene were observed. Obviously, the gene located downstream of the XA gene can possibly include the CYP21A2 as well as the CYP21A1P gene.

Sex-reversed acampomelic campomelic dysplasia with a homozygous deletion mutation in SOX9 gene

Campomelic dysplasia (CD) is a rare autosomal dominant skeletal malformation with or without sex reversal. About 10% of cases that present with milder skeletal features are referred to as acampomelic campomelic dysplasia (ACD). CD and ACD are caused by mutations in SOX9. We report a patient of homozygous SOX9 deletion with minimal skeletal anomaly and female external genitalia in the presence of a male karyotype. The mechanisms explaining the homozygous deletion include a de novo mutation followed by gene conversion, uniparental disomy, or somatic crossing over. Our report highlights the possibility of ACD in XY sex-reversed patients with minimal skeletal presentation.

Analysis of the CYP21A1P pseudogene: indication of mutational diversity and CYP21A2-like and duplicated CYP21A2 genes

The CYP21A1P gene downstream of the XA gene, carrying 15 deteriorated mutations, is a nonfunctional pseudogene that shares 98% nucleotide sequence homology with CYP21A2 located on chromosome 6p21.3. However, these mutations in the CYP21A1P gene are not totally involved in each individual. From our analysis of 100 healthy ethnic Chinese (i.e., Taiwanese) (n=200 chromosomes) using the polymerase chain reaction (PCR) products combined with an amplification-created restriction site (ACRS) method and DNA sequencing, we found that approximately 10% of CYP21A1P alleles (n=195 chromosomes) presented the CYP21A2 sequence; frequencies of P30, V281, Q318, and R356 in that locus were approximately 24%, 21%, 11%, and 34%, respectively, and approximately 90% of the CYP21A1P alleles had 15 mutated loci. In addition, approximately 2.5% (n=5 chromosomes) showed four haplotypes of the 3.7-kb TaqI-produced fragment of the CYP21A2-like gene and one duplicated CYP21A2 gene. We conclude that the pseudogene of the CYP21A1P mutation presents diverse variants. Moreover, the existence of the CYP21A2-like gene is more abundant than that of the duplicated CYP21A2 gene downstream of the XA gene and could not be distinguished from the CYP21A2-TNXB gene; thus, it may be misdiagnosed by previously established methods for congenital adrenal hyperplasia caused by a 21-hydroxylase deficiency.

Incidence of the mucopolysaccharidoses in Taiwan, 1984-2004

Previous studies on the incidence of the various types of mucopolysaccharidoses (MPS) in different populations have shown considerable variation. However, information regarding the incidence of MPS in the Asian population is lacking. An epidemiological study of the MPS disorders in Taiwan using multiple ascertainment sources was undertaken, and incidences of different types of MPS during the period of 1984-2004 were estimated. We compared our data with previous reports in different populations. The combined birth incidence for all MPS cases was 2.04 per 100,000 live births. MPS II (Hunter syndrome) had the highest calculated birth incidence of 1.07 per 100,000 live births (2.05 per 100,000 male live births), comprising 52% of all MPS cases diagnosed. The birth incidences of MPS I (Hurler syndrome), III (Sanfilippo syndrome), IV (Morquio syndrome), and VI (Maroteaux-Lamy syndrome) were 0.11, 0.39, 0.33, and 0.14 per 100,000 live births, respectively, which accounted for 6%, 19%, 16%, and 7% of all MPS, respectively. No cases of MPS III D (Sanfilippo syndrome type D), MPS IV B (Morquio syndrome type B), MPS VII (Sly syndrome) or MPS IX were ascertained during the study period. Overall incidence of MPS in Taiwan was consistent with that reported in Western populations. However, in contrast to the higher incidence of MPS I in most Western populations, this study showed a higher incidence of MPS II in Taiwan. It remains to be investigated whether this discrepancy is attributed to the under-diagnosis of MPS I in Taiwan or to ethnic differences.

The gene founder effect of two spontaneous mutations in ethnic Chinese (Taiwanese) CAH patients with 21-hydroxylase deficiency

CYP21A2 mutations resulting from microconversions of the CYP21A1P sequence in congenital adrenal hyperplasia (CAH) commonly appear in all populations. However, it has not often been described as being due to the gene founder effect. Herein, we investigated two spontaneous mutations of IVS2+1G>A and R316X in ethnic Chinese (Taiwanese) CAH patients to determine whether they share the same haplotype of ancient origin by the analysis of sequence-specific oligonucleotide (SSO) for HLA class I B and sequence-based typing (SBT) for HLA class II DRB1 gene-typing methods. From over 200 CAH families, eight unrelated CAH patients were found and examined: five had the IVS2+1G>A mutation and three had the R316X mutation. Based on HLA typing data, five alleles in five patients with the IVS2+1G>A mutation were consistent with a shared haplotype of the B *3909-DRB1 *160201 allele, and the three alleles in the three patients with the R316X mutation were all the B *460101-DRB1 *080302 allele. The evidence indicates that the haplotype of single-base substitutions of either the IVS2+1G>A or R316X mutation came from the same allele rather than a mutational hot spot, suggesting that the gene founder effect has occurred in the Taiwanese population. This is the first report of the gene founder effect of the CYP21A2 mutation occurring in ethnic Chinese (Taiwanese) CAH patients with 21-hydroxylase deficiency.

Effects of growth hormone treatment on height, weight, and obesity in Taiwanese patients with Prader-Willi syndrome

BACKGROUND

Information regarding the efficacy of growth hormone (GH) therapy in Asian Prader-Willi syndrome (PWS) patients is lacking. We report our experience with GH treatment in children with PWS in Taiwan.

METHODS

Forty-six PWS patients (27 males, 19 females; age range, 1 year 4 months to 13 years 7 months) who received and/or who are currently receiving GH treatment (0.1 IU/kg/day subcutaneously) for a period from 1 year to 3 years were retrospectively analyzed. We evaluated height, weight, body mass index (BMI) and Rohrer index, before and after GH treatment.

RESULTS

After patients had received GH for 1, 2 and 3 years, a significant improvement in mean height standard deviation score (SDS) was noted from -1.24 to -0.31 (p < 0.01), 0.00 (p < 0.001) and -0.26 (p < 0.001), respectively. Mean BMI SDS decreased significantly from 1.93 to 1.13 (p < 0.05) after 1 year of treatment; however, no significant changes were observed afterward. Mean Rohrer index decreased significantly, from 224.2 to 186.6 (p < 0.001), 178.9 (p < 0.001) and 169.3 (p < 0.001). No significant gender or genotype pattern differences were noted among the 4 parameters examined.

CONCLUSION

This 3-year, retrospective study indicates that PWS patients benefit from GH therapy in height increase and improved body composition.

Polysomnographic characteristics in patients with Prader-Willi syndrome

To evaluate the occurrence of sleep-disordered breathing and to clarify the characteristics of sleep among patients with Prader-Willi syndrome (PWS). Overnight continuous EEG-polysomnographic studies were performed in 30 patients with PWS (16 males and 14 females; mean age, 7.4 +/- 4.1 years; age range, 1-19 years) unselected for sleep disturbance. The baseline arterial oxygen saturation (SpO2) was 96.6 +/- 0.6%, with a nadir of 77.2 +/- 10.2%. The rapid eye movement (REM) latency was 67.4 +/- 30.0 min. The percent of total sleep time spent in sleep stages 1, 2, slow wave, and REM were 13.1 +/- 8.2%, 41.9 +/- 10.5%, 21.5 +/- 9.4%, and 21.1 +/- 5.7%, respectively. The respiratory disturbance index (RDI) was 5.8 +/- 3.7/hr and desaturation index (DI) was 8.1 +/- 7.3/hr, respectively. Age-adjusted BMI was associated with more severe hypoxemia during sleep (baseline SpO2, r = -0.53, P < 0.01; nadir SaO2, r = -0.65, P < 0.01; RDI, r = 0.37, P < 0.05; DI, r = 0.53, P < 0.01) and more sleep disruption (arousal index, r = 0.46, P < 0.01). There were no significant associations between gender or genotype pattern (deletion vs. uniparental disomy) and the results of polysomnography. Sleep hypoxemia and sleep disruption are more prevalent in patients with PWS than in normal children. Obesity in these patients is associated with more severe sleep-disordered breathing.

Genotype and phenotype in patients with Prader-Willi syndrome in Taiwan

AIM

Several different genetic defects have been found to result in the characteristic phenotypic expression of Prader-Willi syndrome (PWS).

METHODS

We performed a retrospective analysis of 67 cases of molecularly confirmed PWS diagnosed from January 1980 through July 2006 in five medical centres in Taiwan. Clinical manifestations were compared between patients with deletion and those with maternal uniparental disomy (UPD).

RESULTS

Deletion was present in 56 (84%), UPD in 10 (15%), and a probable imprinting centre deletion or imprinting defect in 1 (1%). PWS with deletion was more likely than that with UPD to be characterized by hypogonadism (p < 0.001), small hands and feet (p < 0.001), and hypopigmentation (p < 0.002). Both maternal (p = 0.015) and paternal age (p = 0.021) were higher in the UPD group. No other clinical features differed significantly different between the two groups.

CONCLUSION

In contrast to most Western populations with a higher incidence of UPD, this study of PWS in Taiwan shows a higher incidence of deletion. There may be subtle phenotypic differences between the UPD and deletion genotypes, but its not clear that these are important clinically.

Prader-Willi syndrome in Taiwan

BACKGROUND

Prader-Willi syndrome (PWS) is a congenital disorder caused by absent expression of paternal genes in 15q11-13 affecting multiple systems. The information concerning the clinical features of this genetic disorder is incomplete in Taiwan.

METHODS

A retrospective analysis was carried out of 70 PWS patients (39 male, 31 females; age range, 1 month-22 years) seen in four major medical centers in Taiwan from January 1980 through June 2005. All cases were confirmed by methylation-specific polymerase chain reaction. The molecular characteristics, birth history, clinical presentation and laboratory studies were analyzed.

RESULTS

Complete genetic analysis was performed in 52 of the 70 patients with PWS. The abnormalities found included deletions in 45 (87%), maternal uniparental disomy (UPD) in five (10%), and a probable imprinting center deletion or an imprinting defect in two (4%). The average weight of the patients at birth was 2588 +/- 540 g. Bone age delay of >2 years and growth hormone (GH) deficiency were noted in 11/40 (28%) and 12/20 (60%), respectively. In the 18 in whom both bone age and GH were assessed, abnormalities of both were found in two (11%). In 2000, Taiwan instituted the Rare Diseases and Orphan Drugs Act and mandated a three-phase screening protocol for PWS. Of the 41 patients diagnosed with PWS before 2000, only four (10%) were diagnosed before the age of 3 months; in the 29 patients diagnosed after 2000, in 15 (52%) the syndrome was confirmed before 3 months of age (P < 0.001).

CONCLUSIONS

The present finding is in contrast to that of most previous reports that indicated a higher incidence of UPD in PWS. It is unclear whether this discrepancy in the incidence of UPD arises from under-diagnosis or because of ethnic differences, a question worthy of further study. The three-phase screening protocol has generated notable improvement in the early diagnosis of PWS in Taiwan.

Pallister-Killian syndrome: report of one case

Pallister-Killian Syndrome (PKS) is a rare sporadic congenital anomaly disorder, characterized by multiple congenital anomalies, especially craniofacial dysmorphism. It is also associated with mental retardation, seizure, skin pigmentation, and visceral malformations such as congenital diaphragmatic hernia, congenital heart defect, anorectal anomalies, and genital malformation. This syndrome usually presents with tissue-limited mosaicism of supernumerary 12p isochromosome i (12p). Moreover, diagnosis of Pallister-Killian Syndrome (PKS) is difficult because the ratio of abnormal to normal karyotyping is much lower in peripheral lymphocytes than in skin fibroblasts. We report the first case in Taiwan, who has tetrasomy 12p mosaic in peripheral lymphocytes.

Novel SOX9 Gene Mutation in Campomelic Dysplasia with Autosomal Sex Reversal

Campomelic dysplasia (CD; OMIM #114290) is an autosomal dominant, frequently lethal dysplasia syndrome whose primary features include angular bowing and shortening of the limbs, and sex reversal in the majority of affected XY individuals. Most CD cases have heterozygous de novo mutations in the coding region of the transcription factor gene SOX9 (SRY-related high-mobility group [HMG] box 9) in chromosome 17q. Here, we report a novel mutation of SOX9 in a female neonate with CD with autosomal sex reversal. Respiratory distress and cyanosis were noted at birth, and endotracheal intubation with mechanical ventilation was performed due to respiratory failure. The presenting phenotypes included dysmorphic face with macrocephaly, prominent forehead, low nasal bridge, cleft palate and micrognathia. Skeletal deformities characteristic of CD were observed, including narrow thoracic cage, hypoplastic scapulae, scoliosis and short limbs with anterolateral femoral and tibial bowing. The karyotype was 46,XY despite female external genitalia. SOX9 gene analysis revealed frameshift mutation (at nucleotide position 1095G-->AT) in the open reading frame, resulting in a frameshift with 211 new amino acids.

Partial androgen insensitivity syndrome with R840H mutation in androgen receptor: report of one case

Androgen insensitivity syndrome (AIS) is the major cause of male pseudohermaphroditism. The severity of the disorders varies widely, ranging from the phenotypic women with female external genitalia in cases of complete AIS to the phenotype of ambiguous genitalia in partial androgen insensitivity syndrome (PAIS) and a rare group of phenotypic normal males with azoospermia. Here, we report an infant of PAIS with a missense mutation at position 2881 (G-->A) in exon 7, encoding substitution of histidine for arginine at codon 840 of the androgen receptor (AR) gene. Both the biochemical and molecular studies are presented. Establishing the diagnosis of PAIS is very important for gender assignment to an infant of ambiguous genitalia. The molecular analysis will facilitate genetic counselling to the maternal side relatives for carrier detection and prenatal diagnosis.

Prevalence of theFMR1 mutation in Taiwan assessed by large-scale screening of newborn boys and analysis of DXS548-FRAXAC1 haplotype

If carrier women could be identified in time and take appropriate measures, fragile X syndrome (FXS) can be prevented. Wide screening of women to be or in their early pregnancy was considered a good approach to identify carriers without misdetection. Nevertheless, we argued against the cost-effectiveness of implementing such a screening program in Taiwan, due to the lower carrier rate found in our pilot study. To reliably estimate the prevalence of mutant FMR1 gene in Taiwan, we anonymously screened 10,046 newborn boys using bloodspot polymerase chain reaction (PCR). Among them, the sample from one boy, who was most likely had FXS, failed repeatedly in PCR amplification. The estimated prevalence of premutation (55-200 CGG repeats) and intermediate alleles (45-54 CGG repeats) was 1:1,674 (n = 6) and 1:143 (n = 70), respectively. All these estimates were constantly lower than that reported in Caucasian populations, with variable statistic significance. Furthermore, when comparing analyses of the distribution of alleles at the two most often investigated microsatellite loci, DXS548 and FRAXAC1, between 100 control and 28 unrelated fragile X chromosomes, we found no apparent founder haplotype prevalent among the fragile X patients. Because a few founder haplotypes were reportedly prevalent in two thirds of fragile X alleles in Caucasians and in Chinese from Central China, we thus suggested that lack of founder fragile X chromosomes might result in a relatively low prevalence of mutant FMR1 gene in a population, as observed in Taiwan.

Contributions of bone maturation measurements to the differential diagnosis of neonatal transient hypothyroidism versus dyshormonogenetic congenital hypothyroidism

AIM

To a) evaluate the contribution of bone maturation in the diagnosis of neonatal transient hypothyroidism versus dyshormonogenetic congenital hypothyroidism in full-term newborns, and b) use bone maturation to test the hypothesis that neonatal transient hypothyroidism is perinatal in onset.

MATERIALS AND METHODS

The study included 20 patients with dyshormonogenetic and 43 with transient hypothyroidism. Thyroid function and measurements of the distal femoral epiphysis area, obtained at the time of first confirmatory diagnosis, were compared between the two groups. The epiphysis area in two control groups with normal thyroid function was also measured and compared with that in patients with transient hypothyroidism, at age 1-3 d (control A), or at the age when normal thyroid function was confirmed (control B).

RESULTS

Mean epiphysis area was 0.04 cm2 in patients with dyshormonogenetic versus 0.22 cm2 in patients with transient hypothyroidism (p < 0.0001). An area <0.05 cm2 was limited to patients with dyshormonogenetic hypothyroidism. Conversely, a normal area (>0.2 cm2) was only observed in patients with transient hypothyroidism. Mean epiphysis areas in control A (0.20 cm2) and in patients with transient hypothyroidism were similar (p = 0.37), consistent with perinatal onset of transient hypothyroidism. Mean epiphysis area in control B (0.31 cm2) was significantly greater than in patients with transient hypothyroidism (p < 0.01).

CONCLUSIONS

A short duration of hypothyroidism can significantly delay bone maturation. Examination of bone maturation at initial confirmatory evaluation yields important information pertaining to congenital hypothyroidism, not only to predict intellectual development, but also to evaluate the risk of dyshormonogenetic hypothyroidism.

Lack of relationship between beta3-adrenergic receptor gene polymorphism and gestational diabetes mellitus in a Taiwanese population

The Trp64Arg polymorphism of beta(3)-adrenergic receptor (ADRB3) has been reported to be associated with insulin resistance and gestational diabetes mellitus (GDM). The objective of this study is to investigate whether the ADRB3 Arg variant confers susceptibility to GDM in a Taiwanese population. A total of 299 pregnant women (mean +/- SD, 31.1 +/- 4.2 years) was recruited. Two-hour, 75-g oral glucose tolerance tests (OGTT) were conducted at 24 to 31 weeks gestation (28.3 +/- 1.6 weeks). Forty-one GDM subjects and 258 controls with normal glucose tolerance (NGT) level were genotyped for the ADRB3 Trp64Arg polymorphism. The genotype distribution and allele frequency of ADRB3 did not significantly differ between GDM and NGT subjects (9.8% v 14.5%). Body weight gain during pregnancy was not different between ADRB3 genotypes. However, the GDM subjects with the Arg64 variant had higher fasting (P =.04) and postload 120 minutes (P =.03) insulin levels as compared with the GDM subjects with the Trp64Trp allele. In all subjects, the women with the Arg64 allele (n = 76) had significantly higher level of insulin secretion (the ratio of Deltainsulin(60)/Deltaglucose(60)) during OGTT than those without (n = 223) (P =.03) despite similar plasma levels of glucose and insulin in both genotypes. Our results indicated that the ADRB3 Trp64Arg variant is not related to the development of GDM and has no effect on obesity during pregnancy in a Taiwanese population. However, ADRB3 polymorphism might be a possible determinant of insulin resistance.

Mutation of IVS2 -12A/C>G in combination with 707-714delGAGACTAC in the CYP21 gene is caused by deletion of the C4-CYP21 repeat module with steroid 21-hydroxylase deficiency

More than 90% of the cases of congenital adrenal hyperplasia are caused by mutations of the CYP21 gene. Approximately 75% of the defective CYP21 genes are generated through intergenic recombination, termed apparent gene conversion, from the neighboring CYP21P pseudogene. Among them, mutation of the aberrant splicing donor site of IVS2 -12A/C>G at nucleotide (nt) 655 is believed to be a result derived from this mechanism and is the most prevalent case among all ethnic groups. However, mutation of 707-714delGAGACTAC rarely exists alone, although this locus is a distance of 53 nt away from IVS2 -12A/C>G. From the molecular characterization of the mutation of IVS2 -12A/C>G combined with 707-714delGAGACTAC in patients with congenital adrenal hyperplasia, we found that it appeared to be in a 3.2-rather than a 3.7-kb fragment generated by Taq I digestion in a PCR product of the CYP21 gene. Interestingly, the 5' end region of such a CYP21 haplotype had CYP21P-specific sequences. Our results indicate that the coexistence of these two mutations is caused by deletion of the CYP21P, XA, RP2, and C4B genes and intergenic recombination in the C4-CYP21 repeat module. Surprisingly, this kind of the haplotype of the mutated CYP21 gene has not been reported as a gene deletion.

An effective strategy of using molecular testing to screen mentally retarded individuals for fragile X syndrome

Fragile X syndrome (FXS) is the most common form of familial mental retardation (MR). It is caused by the expansion of the CGG repeat in the FMR1 gene on the X chromosome. To date, FXS is not treatable, but can be prevented by prenatal genetic examination. Identifying women who carry a full mutation or premutation FMR1 gene is thus very important, and can be done by tracing family members of FXS subjects. However, most of the FXS subjects in Taiwan as well as those in many other countries have not been identified. In this study the authors attempt to develop reliable and inexpensive tests suitable for a large-scale screen of subjects with MR for FXS. Together with their previous study, a total of 311 male and 160 female subjects with MR were screened with nonradioactive Southern blot assay using mixed deoxyribonucleic acid from three subjects of the same sex. From these subjects, nine male subjects and one female FXS subject were diagnosed. All male subjects were also screened with nonradioactive polymerase chain reaction (PCR). These nine male FXS subjects were also detected on the basis of PCR amplification failure. No false-negative results were discerned. The PCR procedure was simplified further by combining it with an analysis of a blood spot on filter paper, which is a much simpler and cheaper method for sample collection and DNA preparation. This method was then used to screen 104 boys with MR. Two of them were suspected, and later confirmed with Southern blot assay, as subjects with FXS. This study suggests that simple PCR combined with blood spot analysis could be a reliable, inexpensive test that is feasible for a large-scale screening of male subjects with MR for FXS. However, Southern blot assay with mixed deoxyribonucleic acid is appropriate for screening female subjects. Based on this strategy, most FXS subjects could be identified easily for further management.

Bilateral ulnar hemimelia in Brachmann-de Lange syndrome: report of one case

Twenty-three cases of Brachmann-de Lange syndrome (BDLS) have been reported in literature here in Taiwan, but none of them had severe upper limb anomalies. We report on a male infant with BDLS who has bilateral ulnar hemimelia.

EEG--a valuable tool in early diagnosis of Angelman syndrome

Angelman Syndrome (happy puppet syndrome) is one of the genetic diseases causing developmental delay in children. Late diagnosis used to be the rule because of delayed appearance of disease markers such as craniofacial dysmorphism, ataxia, unprovoked laughter and seizure. However, reports have described characteristic EEG changes such as 2-3 Hz large amplitude slow wave paroxysms which appear early and are quite specific to the syndrome. With EEG aid, we made very early diagnosis in a 9 month-old young infant. And we would like to advocate the use of EEG study in cryptogenic psychomotor retardation in children.

An R248C mutation of FGFR3 leading to thanatophoric dysplasia type I

Thanatophoric dysplasia (TD) is the most common form of lethal neonatal dwarfism with micromelic shortening of the limbs, macrocephaly, platyspondyly, and reduced thoracic cavity. R248C mutation in the extracellular domain of fibrobast growth factor receptor 3 (FGFR3) was common in TD type I. Two TD type I patients were examined for R248C mutation by use of restriction digestion and direct sequencing. The results showed that both patients carried R248C mutation. Because of the homogeneity of R248C mutation among different ethnic populations, all TD patients should be analysed using this PCR-based method presented in this work.

Arylsulfatase A pseudodeficiency in Chinese

Arylsulfatase A (ASA) pseudodeficiency was found to be much rarer in Taiwan than in most western countries (2.5% versus 7.3%-20% carrier rate). The linkage of two mutations (A2725G and A1788G) in the pseudodeficiency allele was preserved in Chinese, and A2725G did not occur alone. This unusual linkage of mutations has not been fully explained previously because the frequency of A2725G alone was not clear (as low as 4% in the only report). However, A1788G was found in 55 of 160 (34.4%) DNA samples tested in this study. These data suggest that the A2725G mutation occurred in DNA that already contained the A1788G change, at an ancient time in one of our common ancestors.

Oculomotor apraxia in a case of Gaucher's disease with homozygous T1448C mutation

We report a 10-month-old male infant with Type 2 Gaucher's disease. In addition to gradual arrest of neurological development, laryngospasm, opisthotonus, and limb rigidity, he presented characteristic oculomotor apraxia. History taking revealed that he had had abnormal horizontal gaze and had to turn his head to follow an object instead of moving the eyes alone. His eyes were in a divergent position while he was in a deep coma; however, when consciousness improved, he could open eyes with neutral eye position. Due to the impairment of reflex saccades, the doll's eye phenomenon was not reliable in evaluating the brainstem function when he was in the comatose stage. His leukocyte glucocerebrosidase activity was very low, but the typical Gaucher cell was absent in the sample of bone marrow aspiration. Molecular analysis by amplification refractory mutation system (ARMS) screening proved that he was a homozygote for T1448C mutation. To our knowledge, the T1448C gene frequency of Chinese Gaucher's disease is high. Thus, the ARMS screening method is applicable for further genetic diagnosis of Chinese Gaucher patients. Finally, this successful genetic diagnosis makes it possible in the future to perform prenatal diagnosis.