Spectrum of PHEX Mutations and FGF23 Profiles in a Taiwanese Cohort With X-Linked Hypophosphatemia Including 102 Patients.

BACKGROUND/AIM: X-linked hypophosphatemia (XLH), the most common form of hereditary rickets, results from loss-of-function mutations in the phosphate-regulating PHEX gene. Elevated fibroblast growth factor 23 (FGF23) contributes to hypophosphatemia in XLH. This study aimed to characterize PHEX variants and serum FGF23 profiles in Taiwanese patients with XLH. PATIENTS AND METHODS: We retrospectively reviewed the records of 102 patients clinically suspected of having hypophosphatemic rickets from 2006 to 2022. Serum intact Fibroblast growth factor-23 (iFGF23) levels were measured on clinic visit days. PHEX mutations were identified using Sanger sequencing, and negative cases were analyzed using whole-exome sequencing. RESULTS: The majority (92.1%) of patients exhibited elevated FGF23 compared with normal individuals. Among 102 patients, 44 distinct PHEX mutations were identified. Several mutations recurred in multiple unrelated Taiwanese families. We discovered a high frequency of novel PHEX mutations and identified variants associated with extreme FGF23 elevation and tumorigenesis. CONCLUSION: Our findings revealed the PHEX genotypic variants and FGF23 levels in Taiwanese patients with XLH. These results are crucial given the recent approval of burosumab, a monoclonal FGF23 antibody, for XLH therapy. This study provides key insights into the clinical management of XLH in Taiwan.

Congenital generalized lipodystrophy in Taiwan.

BACKGROUND: Congenital generalized lipodystrophy (CGL) is a rare disorder characterized by scarce adipose tissue. This disease is distributed worldwide, but little is known about these patients in the Chinese population. Here, we delineate the phenotype and prognosis of CGL in our cohort. METHODS: Patients diagnosed with CGL from 8 medical centers were reviewed. The initial presentation, laboratory findings, and molecular testing were retrospectively analyzed. RESULTS: A total of 16 patients were analyzed, and the current median age was 3.5 years (range, 9 months-17.5 years). In all patients, molecular results confirmed BSCL2 mutation. c.782dupG (p.Ile262Hisfs*12) was the most common genotype identified. All patients had triangular faces and muscular hypertrophy. In addition, 75% presented with hepatomegaly, 19% had cardiomegaly, and 44% exhibited acanthosis nigricans. Developmental delay was noted in 5 out of 9 patients (56%) with a median developmental quotient (DQ)/intelligence quotient (IQ) of 61. Thirteen patients (81.3%) had high triglyceride levels. Eight patients received leptin analysis, and 7 of them (88%) had low leptin levels. One patient exclusively received a lipid-lowering drug, 4 patients were exclusively placed on a fat-restricted diet, 5 patients were administered combination therapy, and 5 patients received no treatment. Three patients (19%) who developed diabetes mellitus received both oral hypoglycemic agents and insulin. Three patients (19%) experienced loss of ambulation and died prematurely. CONCLUSION: Our findings highlight the uniqueness of the genotype and phenotype in our cohort. Further long-term surveillance for comorbidities is necessary for early detection and management of these patients.

Outcome of early-treated type III Gaucher disease patients.

Recombinant human acid ß-glucosidase GBA (rhGBA) infusion is an effective therapy for non-neuropathic (type I) Gaucher disease (GD), but its effect on subacute neuropathic (type III) GD is still controversial. The most common genotype for type III GD is homozygous c.1448T>C (p.L444P) mutation, and in this study, we treated seven such patients starting from an early age (median 2.1 years; range 1-2.9 years). Before the start of treatment, all patients presented hepatosplenomegaly, anemia, and thrombocytopenia, but with no neurological signs. Normalization of hemoglobin levels and platelet numbers was achieved in all patients in one year. However, after a median treatment period of 7.6 years (2.2-12.0 years), two patients developed horizontal gaze palsy, one had seizures, four demonstrated mental retardation, and five showed kyphosis. Moreover, lymphadenopathy in the neck, thorax, or abdomen was observed in four patients. Therefore, the progression of neurological symptoms in these patients probably reflected the neurologic natural history of type III GD. Residual somatic symptoms, including kyphosis and lymphadenopathy, may be more common than what we thought. An additional treatment will be necessary to improve the outcome of type III GD.

Plasma globotriaosylsphingosine (lysoGb3) could be a biomarker for Fabry disease with a Chinese hotspot late-onset mutation (IVS4+919G>A).

BACKGROUND: Previous studies revealed a high incidence of late-onset Fabry disease mutation, IVS4+919G>A, in Taiwan. However, the natural course is largely unclear and suitable biomarkers for monitoring disease progress are unavailable. METHODS AND RESULTS: Patients carrying IVS4+919G>A or classical Fabry mutations were enrolled in this study. The subjects ranged from newborn to eighty year old adults. Plasma globotriaosylceramide (Gb3) and globotriaosylsphingosine (lysoGb3) were measured by LC-MS/MS in subjects to evaluate the sensitivity of these two biomarkers. All adult males and symptomatic females could be distinguished from healthy controls by an elevated plasma lysoGb3 level. The lysoGb3 level was also related to the left ventricular mass considering gender and age (p<0.01). Moreover, approximately 70% of male and 45% of female newborns already had an elevated plasma lysoGb3 level which increased gradually as the subjects got older (p<0.01). CONCLUSIONS: Plasma lysoGb3 is a more sensitive and reliable biomarker than plasma Gb3. LysoGb3 also correlated with age and left ventricular mass index in Fabry patients with IVS4+919G>A mutation. Because lots of infants with the IVS4+919G>A mutation already had elevated lysoGb3 levels at birth, that indicates that the development of hypertrophic cardiomyopathy may require a long and insidious course after lysoGb3 accumulation.

Intake of phthalate-tainted foods alters thyroid functions in Taiwanese children.

BACKGROUND: On April-May, 2011, two Taiwan chemical companies were found to have intentionally added phthalates, Di-(2-ethylhexyl) phthalate (DEHP) and/or Di-isononyl phthalate, as a substitute of emulsifier to many foodstuffs. This study aimed to investigate whether exposure to these foods altered endocrine functions in children aged ≤10 years and, if so, whether those changes could be reversed by stopping exposure. METHODS: One Phthalates Clinic for Children was established in southern Taiwan between May 31 and June 17, 2011. All eligible children had their exposure information, blood and/or urine specimens collected. Endocrine functions were assessed in serum. The exposure groups were categorized into three (High, >500 ppm, Low, 1-500 ppm, and No, <1 ppm of DEHP). After six months, some children were followed up for the selected endocrine hormones. RESULTS: Sixty children were eligible in this study; all were Tanner stage 1 with no pubic hair. Compared to non-exposed group, both high and low exposure groups had significantly lower serum thyroid-stimulating hormone (TSH) levels (P = 0.001 and 0.024). At six months follow-up, serum triiodothyronine (T3) levels was significantly changed (P = 0.034) in high exposure group (n = 13). For serum estradiol (E2), the detectable rate (≥8 pg/mL) decreased from 76.9% (10/13) to 30.8% (4/13) (P = 0.070). CONCLUSIONS: This study shows that serum TSH levels can be altered when children were exposed to high concentrations of phthalate-tainted foodstuffs. Serum E2 and T3 may be partially recovered after stopping exposure.

CD40 Gene polymorphisms associated with susceptibility and coronary artery lesions of Kawasaki disease in the Taiwanese population.

BACKGROUND: Kawasaki disease (KD) is characterized by systemic vasculitis of unknown etiology. Our previous studies showed expression of CD40 ligand on CD4+ T cells correlated to the coronary artery lesion (CAL) and disease progress in KD. Other studies from Japan suggested the role of CD40L in the pathogenesis of CAL, and this might help explain the excessive number of males affected with KD but cannot be reproduced by Taiwanese population. This study was conducted to investigate the CD40 polymorphism in KD and CAL formation. METHODS: A total of 950 subjects (381 KD patients and 569 controls) were investigated to identify 2 tagging single-nucleotide polymorphisms (tSNPs) of CD40 (rs4810485 and rs1535045) by using the TaqMan allelic discrimination assay. RESULTS: A significant association was noted with regards to CD40 tSNPs (rs1535045) between controls and KD patients (P = 0.0405, dominant model). In KD patients, polymorphisms of CD40 (rs4810485) showed significant association with CAL formation (P = 0.0436, recessive model). Haplotype analysis did not yield more significant results between polymorphisms of CD40 and susceptibility/disease activity of KD. CONCLUSIONS: This study showed for the first time that polymorphisms of CD40 are associated with susceptibility to KD and CAL formation, in the Taiwanese population.

Low penetrance of retinoblastoma for p.V654L mutation of the RB1 gene.

BACKGROUND: Retinoblastoma is caused by compound heterozygosity or homozygosity of retinoblastoma gene (RB1) mutations. In germline retinoblastoma, mutations in the RB1 gene predispose individuals to increased cancer risks during development. These mutations segregate as autosomal dominant traits with high penetrance (90%). METHODS: We screened 30 family members from one family using high resolution melting assay and DNA direct sequencing for mutations in the RB1 gene. We evaluate the phenotype and penetrance of germline mutations of the RB1 gene in a large Taiwanese family. RESULTS: The molecular analysis and clinical details of this family showed phenotypic variability associated with the p.V654L mutation in exon 19 of the RB1 gene in 11 family members. The phenotype varied from asymptomatic to presence of a unilateral tumor. Only four individuals (2 males and 2 females) developed unilateral retinoblastoma, which resulted in calculated low penetrance of 36% (4/11). The four individuals with retinoblastoma were diagnosed before the age of three years. None of their relatives exhibited variable severity or bilateral retinoblastoma. CONCLUSIONS: The diseased-eye ratio for this family was 0.36, which is lower than current estimates. This suggests that the RB1 p.V654L mutation is a typical mutation associated with low penetrance.

A Taiwanese boy with congenital generalized lipodystrophy caused by homozygous Ile262fs mutation in the BSCL2 gene.

Congenital generalized lipodystrophy (CGL) is a rare autosomal recessive disease that is characterized by a near-complete absence of adipose tissue from birth or early infancy. Mutations in the BSCL2 gene are known to result in CGL2, a more severe phenotype than CGL1, with earlier onset, more extensive fat loss and biochemical changes, more severe intellectual impairment, and more severe cardiomyopathy. We report a 3-month-old Taiwanese boy with initial presentation of a lack of subcutaneous fat, prominent musculature, generalized eruptive xanthomas, and extreme hypertriglyceridemia. Absence of mechanical adipose tissue in the orbits and scalp was revealed by head magnetic resonance imaging. Hepatomegaly was noticed, and histological examination of a liver biopsy specimen suggested severe hepatic steatosis and periportal necrosis. However, echocardiography indicated no sign of cardiomyopathy and he showed no distinct intellectual impairment that interfered with daily life. About 1 year later, abdominal computed tomography revealed enlargement of kidneys. He had a homozygous insertion of a nucleotide, 783insG (Ile262fs mutation), in exon 7 of the BSCL2 gene. We reviewed the genotype of CGL cases from Japan, India, China and Taiwan, and found that BSCL2 is a major causative gene for CGL in Asian.

Ganglioneuroma of posterior mediastinum in a 6-year-old girl: imaging for pediatric intrathoracic incidentaloma.

Intrathoracic tumor is a rare entity in the pediatric population and neurogenic tumors account for 40-50% of childhood intrathoracic tumors. They can cause severe symptoms, such as respiratory distress, neurological dysfunction and metabolic disturbances. Posterior mediastinal ganglioneuroma (GN) usually occurs in children and can be found accidentally. Precise preoperative diagnosis is very difficult and has a great influence on surgical intervention. Here, we report a 6-year-old girl with a posterior mediastinal GN that was found incidentally on chest radiography. Computed tomography and magnetic resonance imaging demonstrated a right paraspinal tumor with punctuate calcification and intraspinal extension. (18)F-fluorodeoxyglucose positron emission tomography revealed low-grade fluorodeoxyglucose avidity of this tumor. Computed tomography and magnetic resonance imaging can characterize GN and positron emission tomography is helpful for differentiating benign or malignant lesions.

Noonan syndrome caused by germline KRAS mutation in Taiwan: report of two patients and a review of the literature.

Noonan syndrome is a highly variable disorder that has significant phenotypic overlap with Costello syndrome and cardio-facio-cutaneous syndrome. KRAS mutation was the second reported gene for Noonan syndrome. This study screened for mutation of the KRAS gene in 57 unrelated ethnic Chinese children suffering from Noonan syndrome without PTPN11 gene mutation in Taiwan. This work only identified two patients with different missense mutations (c.40G>A, p.Val14Ile; c.108A>G, p.Ile36Met) in the exon 1 of KRAS gene. This study also analyzed the characteristics of 34 reported cases involving KRAS mutations in the literature. All these patients presented with variable phenotypes, including Noonan syndrome (n = 19), cardio-facio-cutaneous syndrome (n = 7), Costello syndrome (n = 6), and Noonan/cardio-facio-cutaneous syndrome (n = 1). The phenotype of KRAS mutations was generally severe, including short stature, mental retardation, heart defects, etc. In conclusion, this investigation demonstrates that KRAS mutations are the cause in a minority of cases of Chinese patients with Noonan syndrome in Taiwan.

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.

Feminizing adrenocortical adenoma presenting as heterosexual precocious puberty: report of one case.

We report on a case of a 2 2/12-year-old boy with heterosexual precocious puberty secondary to a feminizing adrenocortical adenoma. The boy, with no previous history of disease or treatment, presented with bilateral gynecomastia and pubic hair development (Tanner III breasts and Tanner II pubic hair). Plasma estradiol and testosterone were 410.9 pg/ml and 126.2 ng/dl respectively. Basal plasma LH and FSH levels were within the normal range. Bolus i.v. injection of GnRH showed unresponsiveness of LH and FSH. Abdominal echography and abdominal magnetic resonance imaging revealed a well-defined mass at the left suprarenal region (measuring 4.0 x 2.7 x 3.6 cm in size). After removal of the adrenal tumor, the estradiol and testosterone levels fell to normal in 2 weeks. The gynecomastia and pubic hair regressed with time. The pathology of the tumor showed compact pattern with polygonal cells containing moderate eosinophilic cytoplasm without mitotic figure. These findings were consistent with an adrenocortical adenoma secreting estradiol and testosterone as the cause of the patient's heterosexual precocious puberty.

RBM15-MKL1 (OTT-MAL) fusion transcript in an adult acute myeloid leukemia patient.

The t(1;22)(p13;q13) is a nonrandom chromosomal abnormality in acute leukemia with the fusion oncogene, RBM15-MKL1 (OTT-MAL), identified recently. However, this abnormality has been described only in infants and young children with acute megakaryoblastic leukemia (AMKL). We report a 59-year-old male patient with the diagnosis of acute myeloid leukemia, subtype M1, who harbors an abnormal chromosome +der(1)t(1;22)(p13;q13). The RBM15-MKL1 (OTT-MAL) fusion transcript was also confirmed by the reverse transcriptase-polymerase chain reaction. This unusual abnormality is rare in adult cases of leukemia, and in children it is restricted to AMKL. This report is accompanied by a review of the literature on the t(1;22)(p13;q13).

Case of chronic lymphocytic leukemia with unusual chromosome aberrations.

Chronic lymphocytic leukemia is one of the most common leukemias in the western world and consists of many chromosome aberrations. We report the case of a 74-year-old male patient with chronic lymphocytic leukemia with complex variant translocations t(8;22)(q24;q11) and der(8)t(6;8)(p21;p21) identified by chromosome banding analysis and confirmed by fluorescence in situ hybridization analysis of interphase cells. Because of the rarity of these changes, possible molecular mechanisms associated with this karyotype are discussed.

Kallmann syndrome--a case report.

Kallmann syndrome is a very rare hereditary disease. It is characterized by hypogonadotropic hypogonadism in association with anosmia ot hyposmia, both of which occur as a result of the failure of neuronal migration of the luteinizing hormone releasing hormone (LHRH)--secreting neurons and the neurons of the vemeronasal nerve. It can be autosomal dominant, autosomal recessive, or X-linked mode of inheritance. We report a case of Kallmann syndrome that presented with delay puberty, color blindness, gynecomastia, and absence of smell. Plasma levels of LH, FSH and testosterone were very low. The patient's adrenal and thyroid hormone levels were normal. Chromosome analysis showed 46, XY karyotype without deletion in KAL gene (Xp22.3) from FISH. After 9 months of treatment by HCG and HMG, the amount of pubic hair and the volume of bilateral testes, as well as the level of testosterone had increased. Most importantly, motile sperm count be found in semen.