A novel SLC6A8 mutation associated with intellectual disabilities in a Chinese family exhibiting creatine transporter deficiency: case report.

BACKGROUND: X-linked creatine transporter deficiency (OMIM#300036,CRTR-D) is characterized by cerebral creatine deficiency, intellectual disabilities, severe speech impairment, seizures and behavioral problems. Mutations in the creatine transporter gene SLC6A8, a member of the solute-carrier family 6 mapped to Xq28, have been reported to cause the creatine transporter deficiency. CASE PRESENTATION: The proband presented at 5 yrs. 1 month of age with delays in intellectual and development, seizures and behavioral problems. A novel missense mutation, c.1181C > A (p.Thr394Lys), in the SLC6A8 gene (NM_005629.3) was detected via targeted exome sequencing, and then validated by Sanger sequencing. Multiple in silico variant effect analysis methods, including SIFT, PolyPhen2, PROVEAN, and Mutation Taster predicted that this variant was likely damaging or diseasing-causing. This hemizygous variation was also identified in the affected brother with the same clinical condition and inherited from the heterozygous carrier mother. The diagnosis was suggested by increased urinary creatine/creatinine (Cr:Crn) ratio and markedly reduced creatine content peak by brain proton magnetic resonance spectroscopy (MRS). The proband's mother became pregnant with a 3rd sibling, in whom the Sanger sequencing result of c.1181C > A was negative. CONCLUSION: The novel mutation c.1181C > A in the SLC6A8 gene reported in a Chinese family has expanded the mutation spectrum of CRTR-D. The combination of powerful new technologies such as targeted exome sequencing with thorough systematic clinical evaluation of patients will improve the diagnostic yield, and assist in genetic counselling and prenatal diagnosis for suspected genetic disorders.

Association of TUSC3 gene polymorphisms with non-syndromic mental retardation based on nuclear families in the Qinba mountain area of China.

TUSC3 interacts with the protein phosphatase 1 and magnesium ion transport system, which plays an important role in learning and memory. Abnormal conditions of learning and memory are common clinical characteristics of mental retardation (MR). However, the association of TUSC3 genetic polymorphisms with MR remains unknown. A total of 456 DNA samples including 174 nuclear families containing MR were collected in the Qinba mountain area of China. The genotypes of eight tag single nucleotide polymorphisms of TUSC3 were evaluated with traditional genetic methods. Family-based association tests, transmission disequilibrium tests (TDTs), and haplotype relative risk (HRR) analyses were performed to investigate the association between genetic variants of the TUSC3 gene and MR. The genetic polymorphisms rs10093881, rs6530893, and rs6994908 were associated with MR (all P values <0.05) based upon the results of single-site TDT and HRR analyses. The haplotype block consisting of rs6530893 and rs6994908, harboring the sixth exon of TUSC3, was also associated with MR (all P values <0.05). This study demonstrated an association between genetic polymorphisms of the TUSC3 gene and MR in the Qinba mountain area, the sixth exon of which might contribute to the risk of MR. However, further studies are needed on the causal mechanisms in this association.

Correlation between cystathionine beta synthase gene polymorphisms, plasma homocysteine and idiopathic mental retardation in Indian individuals from Kolkata.

Deficiency in cystathionine beta synthase (CBS) enzyme sometimes leads to hyperhomocysteinemia/homocystinuria, conditions often associated with mental retardation (MR). In this investigation, association of idiopathic MR (IMR) with six CBS gene polymorphisms and fasting total plasma homocysteine (plHcy) was explored. Nuclear families with IMR probands (N=180) and control subjects (N=106) were recruited. Genomic DNA was subjected to PCR amplification and RFLP analysis. plHcy was measured by enzyme immunoassay. Data obtained was subjected to statistical analyses. Linkage disequilibrium between polymorphic sites was computed. T833C/844ins68 polymorphism revealed significant maternal transmission in IMR cases. The 31bpVNTR 21 repeat allele was significantly higher in male IMR cases as compared to sex-matched controls (P=0.004). A significant difference was also noticed in genotype frequencies of male IMR cases (P=0.005). Four other sites, G919A, C1105T, G1316A and G1330A, were not polymorphic in the studied population. While no significant contribution of any particular genotype was observed, plHcy level was significantly higher in male IMR cases as compared to sex-matched controls (P=0.0001). The data presented here is probably indicative of a higher risk of IMR in male subjects in association with two CBS polymorphisms and mild elevation in plHcy concentration.

Sampling survey on intellectual disability in 0 approximately 6-year-old children in China.

OBJECTIVES: To understand the current status of intellectually disabled children and the prevalence of intellectual disability (ID) in children aged 0 approximately 6 years and its risk factors, and to provide scientific evidence to formulate relevant policies for helping intellectually disabled children. METHODS: Multiphase, stratified, unequal proportional and cluster sampling was adopted to investigate 60 124 children aged 0 approximately 6 years. All the children investigated were screened for ID using the Denver Developmental Screening Test, and those with positive screening test would be further diagnosed by varied specialists using the Gesell Developmental Inventory. RESULTS: In total, 560 of 60 124 children were diagnosed as intellectually disabled with an overall prevalence of 0.93%. Prevalence of ID was highest in children living in medium-developed areas with a prevalence of 1.20%, higher than in those living in developed areas (0.75%) and in underdeveloped areas (0.84%). It was higher in rural areas (1.03%) than in urban areas (0.83%), and higher in boys (1.01%) than in girls (0.84%). Prevalence of ID increased with the age of children and decreased with the educational level of their parents. CONCLUSIONS: The study suggested that ID is still prevalent in the children of China, and rehabilitation for them is lagging behind current needs. Early prevention of ID in children and pre-school education for them should be strengthened.

Síndrome de Rett: microcefalia con retardo mental y autismo: Reporte de un caso / Rett Syndrome: microcephaly with mental retardation and autism: a case report

El síndrome de Rett es un grave proceso del desarrollo neurológico que afecta exclusivamente mujeres, se considera una enfermedad monogénica dominante ligada al cromosoma X debida a mutaciones en el gen MECP2 codificador de la proteína 2 de unión a metil-CpG. La paciente fue normal hasta los 18 meses de vida cuando inició con deterioro en sus destrezas psicomotoras: marcha atáxica y pérdida del movimiento intencionado de las manos; alteración social y de conducta con autismo infantil y retardo mental importante. Esta enfermedad suele, frecuentemente, estar mal diagnosticada como autismo o parálisis cerebral y carece de tratamiento específico.

Rett syndrome is a severe neurodevelopment disorder which affects exclusively women. It is considered a dominant disease linked to the X chromosome; it is due to mutations in the MECP2 gene which encodes the methyl-CpG binding 2 protein. This patient had a normal development until 18 months of age, then a deterioration of her psychomotor skills with ataxia and loss of purposeful use of the hands began; the behavioral and social areas were also affected with autism and progression to profound mental retardation. The syndrome is misdiagnosed often as autism or cerebral palsy and has no specific treatment.

A longitudinal study of developmental outcome of infants with bronchopulmonary dysplasia and very low birth weight.

OBJECTIVE: Bronchopulmonary dysplasia (BPD) is now the leading cause of lung disease in US infants. In a large regional cohort, we tested the hypothesis that despite innovations in neonatal care, very low birth weight (VLBW) infants (<1500 g) with BPD had poorer developmental outcomes than nonaffected infants during the first 3 years of life, and that BPD predicted poorer outcome beyond the effects of other risk factors. METHODS: Three groups of infants (122 with BPD, 84 VLBW without BPD, and 123 full-term) were followed longitudinally to 3 years of age with the Bayley Scales of Mental and Motor Development. Comparison groups of VLBW infants without BPD and full-term infants did not differ in sex, race, or socioeconomic status. Statistical analyses included hierarchical and stepwise multiple regression. RESULTS: Infants with BPD performed more poorly at all ages. By 3 years, cognitive and/or motor development was in the range of retardation (<70 standard score) for 21% to 22% of infants with BPD. In multiple regression analyses controlling for socioeconomic and neonatal risk conditions, BPD had an independent negative effect on motor outcome at 3 years. Neurologic risk, a summary measure of neurologic problems other than intraventricular hemorrhage, and the presence of BPD independently predicted motor delay. By 3 years, social class, race, and neurologic risk predicted mental outcome, suggesting that the specific effects of BPD are primarily on the motor domain. CONCLUSIONS: In VLBW infants, BPD predicts poorer motor outcome at 3 years, after control for other risks. Cohorts of infants with BPD also had higher rates of mental retardation, associated with greater neurologic and social risk. These findings underscore the need for intensive prevention and habilitation efforts for this growing group of VLBW survivors, as well as investigation into the potential role of BPD in the higher rates of learning disabilities in VLBW cohorts at school age.

[Neuroectodermal dysplasia in 2 Uzbek families]. / Sindrom neiroektodermal'noi displazii v dvukh Uzbekskikh sem'iakh.

The authors present the clinical and genealogical description of 6 patients with neuroectodermal dysplasia diagnosed by a medical expedition party in Khankin district of the Khorezm region. Unique combination of clinical signs (total alopecia, microcephalia, oligophrenia, hyperhydrosis and hypogenitalism) helped differentiating the syndrome from other well-known hereditary neuroectodermal dysplasias. The nature of the syndrome segregation in the families suggested its autosomal-recessive mode of inheritance.

A variant of Fukuyama congenital muscular dystrophy in a non-Japanese child.

We report a case of Fukuyama congenital muscular dystrophy with inflammatory infiltrate on muscle biopsy in an American girl of non-Japanese ancestry. The child was hypotonic, had decreased muscle strength in all extremities, and poor head control. Her mental and motor development were delayed. She developed generalized seizures at 19 months of age. Her muscle enzymes were abnormal; cranial computed tomography demonstrated hypoplasia of the cerebellum. Electromyogram was normal. Deltoid muscle biopsy documented scattered basophilic regenerating myofibers and focal atrophic fibers with focal increases of endomysial connective tissue, small endomysial foci of inflammatory cells, and occasional perimysial, perivenular lymphocytic infiltrates. Prednisone therapy produced some decrease in serum muscle enzyme levels.