Mandibuloacral dysplasia type A-associated progeria caused by homozygous LMNA mutation in a family from Southern China.

BACKGROUND: Mandibuloacral dysplasia type A (MADA) is a rare autosomal recessive disorder, characterized by growth retardation, skeletal abnormality with progressive osteolysis of the distal phalanges and clavicles, craniofacial anomalies with mandibular hypoplasia, lipodystrophy and mottled cutaneous pigmentation. Some patients may show progeroid features. MADA with partial lipodystrophy, more marked acral, can be caused by homozygous or compound heterozygous mutation in the gene encoding lamin A and lamin C (LMNA). MADA and Hutchinson-Gilford progeria syndrome are caused by the same gene and may represent a single disorder with varying degrees of severity. MAD patients characterized by generalized lipodystrophy (type B) affecting the face as well as extremities and severe progressive glomerulopathy present heterozygous compound mutations in the ZMPSTE24 gene. CASES PRESENTATIONS: We described a rare pedigree from Southern China, among them all three children presented with phenotypes of MADA associated progeria. The two elder sisters had developed severe mandibular hypoplasia associated progeria since the age of 1 year. The eldest sister showed a progressive osteolysis. The youngest son of 10 months showed severer lesions than those of his sisters at the same age, and presented possible muscle damage, and his symptoms progressed gradually. Three genes mutations including LMNA, ZMPSTE24 and BANF1 were tested in the family. LMNA gene sequencing revealed a homozygous missense mutation, c.1579C > T, p.R527C for all three siblings, and heterozygous mutations for their parents, whereas no mutations of ZMPSTE24 and BANF1 genes was detected among them. CONCLUSIONS: The same homozygous mutation of c.1579C > T of LMNA gene led to MADA associated progeria for the present family. The course of osteolysis for MADA is progressive.

The intracellular controlled release from bioresponsive mesoporous silica with folate as both targeting and capping agent.

A smart mesoporous silica nanocarrier with intracellular controlled release is fabricated, with folic acid as dual-functional targeting and capping agent. The folate not only improves the efficiency of the nanocarrier internalized by the cancer cells, but also blocks the pores of the mesoporous silica to eliminate premature leakage of the drug. With disulfide bonds as linkers to attach the dual-functional folate within the surface of mesoporous silica, the controlled release can be triggered in the presence of reductant dithiothreitol (DTT) or glutathione (GSH). The cellular internalization via folate-receptor-mediated endocytosis and the intracellular controlled release of highly toxic anticancer drug DOX were demonstrated with an in vitro HeLa cell culture, indicating an efficient cancer-targeted drug delivery.

[Genotype, phenotype analysis and follow-up study on patients with Duchenne/Becker muscular dystrophy].

OBJECTIVE: To improve the diagnosis and management of Duchenne/Becker muscular dystrophy(DMD/BMD). METHODS: Clinical features of 90 cases of DMD/BMD were collected. Genomic DNA was extracted using standard procedures from the peripheral blood leukocytes, and multiplex ligation-dependent probe amplification (MLPA) was applied to detect DMD gene to identify genetic mutation. For those patients whose deletion/duplication mutation was not identified, FKRP gene mutation analysis was performed using PCR-DNA direct sequence. All the cases were followed up. RESULTS: Among the 90 cases of clinically diagnosed DMD/BMD, exons deletion of DMD was detected in 58 cases (64.44%), and exons duplication in 9 (10.00%). Among the 34 mothers with an affected boy but without previous genetic conformation, 17 were confirmed to be carriers with gene deletion/duplication. None of the 23 cases, without detected DMD gene deletion/duplication, carried FKRP gene mutation. Fourteen children were given short-term intermittent prednisone therapy (0.75 mg/kg daily during the first 10 days of each month). The course was not long enough and the sample size was too small to conclude any benefits or side effects. Prenatal diagnosis was provided for one mother in her next pregnancy detecting a female carrier fetus. CONCLUSION: DMD gene deletions mainly occurs between exons 45 and 54, while duplications mostly at 5'-terminus. Identification of the characteristics and types of gene mutation may facilitate the recognition and prognosis prediction of DMD/BMD. MLPA is a non-complex and quick diagnostic tool for DMD/BMD and its carriers, and also helpful in genetic counseling.

[The correlation of CAGs repeat size with age of onset in patients with Kennedy's disease].

OBJECTIVE: To investigate the correlation of CAGs repeat size and age of onset in patients with Kennedy's Disease (KD). METHODS: We detected the number of CAG repeats in the androgen receptor genes in 30 patients with KD. The correlation of CAGs repeat size with age of onset was analyzed. At the same time, the Appel scale that could represent the degree of motor functional impairment was scored in every patient. The correlation of Appel scale with CAGs repeat size and the course of disease were analyzed. RESULTS: Significant correlation was found between the number of CAGs with age of onset (r = -0.671, P < 0.01). There was also correlation between the Appel score and the course of disease (r = 0.855, P < 0.01), but no correlation between the Appel score and the number of CAGs (r = 0.100, P = 0.601). CONCLUSIONS: It is found that in Kennedy' disease, as well as in other CAG repeat diseases, the length of polyglutamine tract determines the age of onset, but has no correlation with the severity of the disease.

[Multiplex ligation-dependent probe amplification analysis of subtelomeric chromosome rearrangements in children with idiopathic mental retardation].

OBJECTIVE: To study the rate of subtelomeric rearrangements in patients with idiopathic mental retardation (MR) and to search the cause of MR. METHODS: DNA was extracted and purified from peripheral blood leukocytes of 180 patients with idiopathic MR. DNA was tested using specific subtelomeric multiplex ligation-dependent probe amplification (MLPA) kits P036B/C and P070 according to manufacturer's instructions. The amplification products were separated by capillary electrophoresis using an ABI 3100 automated sequencer and size standard. MLPA data were extracted by GeneScan Analysis software. Data normalization and analysis were performed with the built-in MLPA application in GeneMarker. RESULTS: Among 180 patients with idiopathic MR, 12 had pathological subtelomeric deletions including 3 cases with a 4p deletion, 2 cases with a deletion at 9q and 22q respectively, 1 case with a deletion at 1p, 7p, 8p, 9q and 12q respectively. Subtelomeric rearrangements were responsible for 7% cases of idiopathic mental retardation. CONCLUSION: Subtelomeric rearrangement is a common cause of idiopathic mental retardation.

[Methylation-specific multiplex ligation-dependent probe amplification in diagnosis of Prader-Willi syndrome and Angelman syndrome].

OBJECTIVE: To verify the sensitivity and reliability of methylation-specific multiplex ligation-dependent probe amplification (MS-MLPA) and to develop a simple, accurate, reliability method of genetic diagnosis for AS and PWS. METHODS: Peripheral blood samples were collected from 4 suspected AS patients, 2 suspected PWS patients, 2 normal persons, and 2 molecular biologically proven positive controls (1 AS patient and 1 PWS patient). DNA was extracted and purified. MS-MLPA was used to detect the methylation of the CpG dinucleotide and the copy number in the 15q-q13 region. The results of MS-MLPA were confirmed by MSP. RESULTS: Three cases with maternal deletion on 15q11-q13 region and one case with paternal uniparental disomy (UPD) or imprinting center defect in 15q11-q13 region were found in the 4 suspected AS patients. One PWS case was found to be with paternal deletion in 15q11-q13 region and the other with paternal deletion in 15q11-q13 region or UPD or imprinting center defect in 15q11-q13 region. CONCLUSION: MS-MLPA is a simple, rapid, accurate, and reliable method of genetic test.

[The same mutation Glu208Lys in the GJB1 gene was detected in 2 families with X-linked Charcot-Marie-Tooth disease].

Mutation of GJB1 gene was investigated in two families with X-linked Charcot-Marie-Tooth disease. Genomic DNA from venous blood samples was prepared. The coding sequence of the GJB1 gene was amplified from genomic DNA. PCR products were analyzed by single strand conformational polymorphism (SSCP) method. The PCR product having an abnormal pattern was sequenced to detect the mutation. It was found that the samples of all patients and one little girl with normal phenotype showed an abnormal SSCP band, but not detected in the other unaffected members in the first large family. In the second small family, an abnormal SSCP band was found in all the patients, but not detected in the unaffected member. The result of DNA sequencing demonstrated that both families had a same mutation of 622G-->A, which resulted in a substitution of Glu208Lys. This mutation has not been reported previously in China.

[Detection of subtelomeric rearrangements in patients with idiopathic mental retardation/developmental delay].

OBJECTIVE: To detect subtelomeric rearrangement in patients with idiopathic mental retardation/developmental delays (MR/DD) and to provide new methods and evidence for the etiologic diagnosis of MR/DD in China. METHODS: 1. INCLUSION CRITERIA: (1) Moderate to severe MR/DD; (2) no definite perinatal brain injury; (3) no toxication, hypoxia, infection of central nervous system and cranial trauma; (4) routine karyotyping is normal; (5) no evidence of typical inherited metabolic disorder or specific neurodegenerative disorders from cranial neuro-imaging and blood/urinary metabolic diseases screening; (6) no mutation of FMR1 gene in male patients plus one of the following criteria: (1) positive family history of MR; (2) positive family history of miscarriages and perinatal deaths; (3) abnormal growth; (4) facial and non-facial dysmorphism. 2. Multiplex ligation-dependent probe amplification (MLPA) and fluorescence in situ hybridization (FISH) were applied to detect subtelomeric rearrangements in patients and their parents. RESULTS: Four cases were identified from 39 selected cases with subtelomeric rearrangements (10%), including der (2) t (2; 4) (pter; pter), 11qter del, 8pter del, and 15p11.2 del. The first two abnormalities of chromosome subtelomeric regions have not been reported yet. All these cases had some small dysmorphologies, such as microcephaly, hypertelorism, low nasal bridge, and three of them had hypotonia. One case had recurrent seizure and abnormal behavior (laughter not associated with happiness), and another case with dysgenesis of corpus callosum and septum pellucidum. Family and perinatal histories were normal for all cases. All chromosome rearrangements were de novo which were not from the parents with normal phenotype. It indicated that all these abnormal rearrangements should be responsible for the mental retardation phenotype of these patients. The phenotype of case 4 was similar to Angelman syndrome, his deletion was actually a kind of interstitial rearrangements. It will be confirmed by DNA methylation test to determine whether the deleted allele was of maternal origin. CONCLUSIONS: The subtelomeric rearrangements were found in 10% patients with idiopathic MR. It indicated that subtelomeric rearrangements should be one of major reasons of MR/DD related to genetic factors. Two novel subtelomeric rearrangements were identified. These de novo rearrangements are probably disease related, because they are not inherited from their parents with normal phenotype. The detection should be carried out for all the patients with idiopathic MR/DD with unknown origin, because one cannot figure out the specific signs for subtelomeric rearrangements. Sequentially use of MLPA and FISH is a more efficient and economic method to detect the subtelomeric rearrangements.

Clinical and genetic features of DYT1 and DYT5.

Dystonia is a syndrome which is characterized by sustained muscle contractions, producing twisting, repetitive, and patterned movements, or abnormal postures. According to genetic basis, dystonia is classified into 13 subtypes. We mainly discussed two subtypes, DYT1 and DYT5, in this review. Early-onset primary dystonia is caused by the mutation of DYT1 gene, which leads to TORSINA abnormal. GTP cyclohydrolase 1 (GTPCH1)-deficient DRD (DYT5) is caused by the mutations of GCH1 gene. By genetic testing, we can confirm clinical diagnosis of each subtype and develop prenatal diagnosis for it.

[Comparison of Rhesus boxes in Hans and Uighurs].

OBJECTIVE: To study the difference and similarity between Hans and Uighurs in regard to Rhesus box and its significance. METHODS: The sequence specific primers of upstream, downstream and hybrid Rhesus boxes were designed on the basis of RHD gene sequence. The upstream, downstream and hybrid Rhesus boxes were determined by polymerase chain reaction-sequence specific primer(PCP-SSP) and mismatched PCR. RESULTS: The percentage of RHD-/RHD-, RHD+/RHD- and RHD+/RHD+ genotypes ascertained in the unrelated Hans with RhD(-) were 61.40%, 34.21% and 4.39% respectively, while those in the unrelated Chinese Uighurs with RhD(-) were 94.44%, 2.78% and 2.78% respectively. Furthermore, all 6 cases of some other minorities were RHD-/RHD- types. The percentage of RHD-/RHD- and RHD+/RHD- genotypes ascertained in the unrelated Chinese Uighurs were significantly higher than those in Chinese Hans (P < 0.01), whereas no statistically significant difference in the percentage of RHD+/RDH+ genotype between the two groups was observed (P > 0.05). CONCLUSION: The Rh blood group of Uighurs in Xingjiang possesses both Oriental and Caucasian characteristics, which embodies a special ethnical aspect of the Chinese nation and is in accord with the anthropologic research results.

[Study on detection of samples of Rh-weak D and Del].

To study the detection of weak D and Del from samples initially screened RhD(-), RhD phenotype was initially screened by routine serological test, out of which weak D phenotype was detected by indirect antiglobulin test (IAT) and Del phenotype was detected by chloroform-trichloroethylene absorption-elution test. The results showed that 56 samples were RhD(-) confirmed by routine serology test, which were screened out of 26 200 donors, among them 5 samples were typed as weak D by IAT and 9 cases samples were typed as Del by absorption-elution test. In conclusion, the samples which typed as RhD(-) by routine serological test must be identified by IAT and chloroform-trchloroethylene absorption test is order to detect weak D and Del phenotype. It is important for clinical transfusion safely.

[Determination of human RHD gene rhesus box and its significance].

The aim was to determine RHD zygosity, further to investigate genetic structure of RHD gene, and to predict hemolytic disease of newborn (HDN). The upstream box, downstream box, and hybrid box of RHD gene were determined by PCR-SSP with 4 primers under the same conditions. The results showed that only hybrid box could be determined in RHD(-)/RHD(-) homozygosity. All the upstream box, downstream box, and hybrid box could be determined in RHD(+)/RHD(-) heterozygosity, while upstream box and downstream box except hybrid box could be determined in RHD(+)/RHD(+) homozygosity. Out of 50 cases of RhD(+), 5 cases (10%) were RHD(+)/RHD(-) heterozygosity, and the others (90%) were RHD(+)/RHD(+) homozygosity. 54 cases (55.1%), 36 cases (36.7%) and 8 cases (8.2%) were RHD(-)/RHD(-) homozygosity, RHD(+)/RHD(-) heterozygosity, and RHD(+)/RHD(+) homozygosity respectively in 98 unrelated cases of RhD(-) Chinese Hans. 2 cases of weak D were proved to be RHD(+)/RHD(-) heterozygosity. Out of 16 D(el) types, the upstream box, downstream box, and hybrid box could be determined in 10 cases (37.5%) and the upstream box and downstream box except hybrid box could be determined in 6 cases. Results detecting of RHD 10 exons in above samples proved the correctness of the method. It is concluded that the method is suitable for clinical application with its simplicity and veracity. There are many noneffective RHD genes (44.9%) in Chinese Hans with RhD(-) phenotype.

[Exon polymorphism of human RHD gene].

OBJECTIVE: To study exon polymorphism of human RHD gene and investigate the genetic mechanism of RhD-negative individuals. METHODS: PCR using sequence-specific primers (PCR-SSP) was performed on 40 RhD-positive, 120 RhD-negative and 2 weak D blood samples. RESULTS: All 10 exons could be detected in the 40 RhD-positive and 2 weak D samples. Out of the 120 RhD-negative samples, 28 (23.33%) carried 10 exons, 19 (15.83%) lost most of the 10 exons (with mainly intermediate deletion), and 73 (60.83%) had deletion of all the 10 exons; 19 samples of Del phenotype identified from the 120 RhD-negative samples had all the 10 exons. CONCLUSION: Polymorphism of the exon structure of RHD gene is present in RhD-negative individuals, characterized chiefly by gross deletion, partial deletion and non-deletion.