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Biomedical subjects

C A Kim

Publications and source records attributed to C A Kim.

At least 19 recordsLinked to original sources
PubMed2006

Whole-genome array-CGH screening in undiagnosed syndromic patients: old syndromes revisited and new alterations.

We report array-CGH screening of 95 syndromic patients with normal G-banded karyotypes and at least one of the following features: mental retardation, heart defects, deafness, obesity, craniofacial dysmorphisms or urogenital tract malformations. Chromosome imbalances not previously detected in normal controls were found in 30 patients (31%) and at least 16 of them (17%) seem to be causally related to the abnormal phenotypes. Eight of the causative imbalances had not been described previously and pointed to new chromosome regions and candidate genes for specific phenotypes, including a connective tissue disease locus on 2p16.3, another for obesity on 7q22.1-->q22.3, and a candidate gene for the 3q29 deletion syndrome manifestations. The other causative alterations had already been associated with well-defined phenotypes including Sotos syndrome, and the 1p36 and 22q11.21 microdeletion syndromes. However, the clinical features of these latter patients were either not typical or specific enough to allow diagnosis before detection of chromosome imbalances. For instance, three patients with overlapping deletions in 22q11.21 were ascertained through entirely different clinical features, i.e., heart defect, utero-vaginal aplasia, and mental retardation associated with psychotic disease. Our results demonstrate that ascertainment through whole-genome screening of syndromic patients by array-CGH leads not only to the description of new syndromes, but also to the recognition of a broader spectrum of features for already described syndromes. Furthermore, on the technical side, we have significantly reduced the amount of reagents used and costs involved in the array-CGH protocol, without evident reduction in efficiency, bringing the method more within reach of centers with limited budgets.

Adolescent↗
PubMed2005

Mucopolysaccharidosis type VI: Identification of novel mutations on the arylsulphatase B gene in South American patients.

Mucopolysaccharidosis type VI (Maroteaux-Lamy syndrome, MPS VI) is an autosomal recessive disorder caused by deficiency of N-acetylgalactosamine-4-sulphatase (ARSB),which leads to the lysosomal accumulation and excretion of dermatan sulphate (DS). In this study, 13 unrelated MPS VI patients (12 Brazilian and 1 Chilean) were investigated regarding the identification of the ARSB gene mutations using PCR, SSCP and sequencing. The exons with altered mobility on SSCP were sequenced, as well as all the exons of patients with no SSCP alteration. Seven novel mutations were identified: D59N, L72R, Q88H, P93S, R197X, 1279delA and c.1143-8T > G. The previously reported mutations 1533del23, R315Q and 427delG were found in six, three and two alleles respectively. The other mutations already reported, S384N and G144R, were found in only one allele. In addition, three polymorphisms previously described (V358M, V376M and P397P) were detected in the patients analysed. Our findings are in agreement with the literature confirming the great genetic heterogeneity associated with MPS VI.

Adolescent↗
PubMed2005

Impact of molecular mechanisms, including deletion size, on Prader-Willi syndrome phenotype: study of 75 patients.

Prader-Willi syndrome (PWS) can result from a 15q11-q13 paternal deletion, maternal uniparental disomy (UPD), or imprinting mutations. We describe here the phenotypic variability detected in 51 patients with different types of deletions and 24 patients with UPD. Although no statistically significant differences could be demonstrated between the two main types of PWS deletion patients, it was observed that type I (BP1-BP3) patients acquired speech later than type II (BP2-BP3) patients. Comparing the clinical pictures of our patients with UPD with those with deletions, we found that UPD children presented with lower birth length and started walking earlier and deletion patients presented with a much higher incidence of seizures than UPD patients. In addition, the mean maternal age in the UPD group was higher than in the deletion group. No statistically significant differences could be demonstrated between the deletion and the UPD group with respect to any of the major features of PWS. In conclusion, our study did not detect significant phenotypic differences among type I and type II PWS deletion patients, but it did demonstrate that seizures were six times more common in patients with a deletion than in those with UPD.

Adolescent↗
PubMed2005

CHILD syndrome caused by a deletion of exons 6-8 of the NSDHL gene.

The X-linked dominant CHILD syndrome (congenital hemidysplasia with ichthyosiform nevus and limb defects) is a rare developmental defect characterized by a strictly lateralized inflammatory nevus. In the majority of cases, the right side of the body is affected. Ipsilateral hypoplastic lesions may involve the brain, skeletal structures, lungs, heart or kidneys. We describe a case of CHILD syndrome involving the left side of the body. Absence of metacarpal, metatarsal and phalangeal bones of the left hand and foot resulted in oligodactyly, with only 3 fingers and 1 toe. An ipsilateral inflammatory epidermal nevus with hyperkeratosis, parakeratosis, acanthosis and perivascular lymphohistiocytic infiltrate was strictly confined to the left half of the patient's body. The phenotype was shown to be associated with a deletion of exons 6-8 of the X-linked NSDHL gene, confirming that CHILD syndrome is due to loss of function of an enzyme involved in cholesterol biosynthesis.

3-Hydroxysteroid Dehydrogenases↗
PubMed2004

Clinical and biochemical study of 28 patients with mucopolysaccharidosis type VI.

This paper presents data collected by a Brazilian center in a multinational multicenter observational study of patients with mucopolysaccharidosis type VI (MPS VI), aiming at determining the epidemiological, clinical, and biochemical profile of these patients. Twenty-eight south-American patients with MPS VI were evaluated through medical interview, physical exam, echocardiogram, electrocardiogram, ophthalmologic evaluation, quantification of glycosaminoglycans (GAGs) in urine, and measurement of the activity of N-acetylgalactosamine-4-sulfatase (ARSB) in leukocytes. 92.9% of patients were Brazilian. Mean age at diagnosis and at evaluation was 48.4 months and 97.1 months, respectively. 88% of patients had onset of symptomatology before the age of 36 months. Consanguinity was reported by 27% of the families. Mean weight and height at birth were 3.481 kg and 51.3 cm, respectively. The most frequently reported clinical manifestations were short stature, corneal clouding, coarse facial features, joint contractures, and claw hands. All patients presented with echocardiogram changes as well as corneal clouding. Mean ARSB activity in leukocytes was 5.4 nmoles/h/mg protein (reference values: 72-174), and urinary excretion of GAGs was on average 7.9 times higher than normal. The number of clinical manifestations did not show a significant correlation with the levels of urinary GAGs nor with the ARSB activity. Also, no significant correlation was found between the levels of urinary GAGs and the ARSB activity. It was concluded that MPS VI has high morbidity and that, when compared with data published in the literature, patients in our study were diagnosed later and presented with a higher frequency of cardiological findings.

Brazil↗
PubMed2003

High specificity PCR screening for 22q11.2 microdeletion in three different ethnic groups.

Congenital heart defects are the most common of all human birth defects. Numerous studies have shown that a deletion within chromosome 22q11 is associated with DiGeorge syndrome and certain forms of sporadic congenital cardiovascular disease. We have determined the value of a PCR assay using markers D22S941, D22S944 and D22S264 designed for the screening of 22q11.2 deletion through consecutive homozygosity in an ethnically admixed urban population. The study population comprised 149 unrelated men and women from three different ethnic groups (white, mulatto and black). Test specificity for the overall population was estimated at 98.3%. We found no significant difference when comparing heterozygosity indices and ethnicity (P value = 0.43 (D22S944), 0.22 (D22S264), and 0.58 (D22S941)). There was no significant difference regarding assay specificity between the three different ethnic groups studied. This assay could constitute a cost-effective way to screen a large number of patients at increased risk, since PCR techniques are easily available, are fast, can be automatized, and are significantly less expensive than fluorescence in situ hybridization.

Chromosome Deletion↗
PubMed2001

LDL receptor-related protein 5 (LRP5) affects bone accrual and eye development.

In humans, low peak bone mass is a significant risk factor for osteoporosis. We report that LRP5, encoding the low-density lipoprotein receptor-related protein 5, affects bone mass accrual during growth. Mutations in LRP5 cause the autosomal recessive disorder osteoporosis-pseudoglioma syndrome (OPPG). We find that OPPG carriers have reduced bone mass when compared to age- and gender-matched controls. We demonstrate LRP5 expression by osteoblasts in situ and show that LRP5 can transduce Wnt signaling in vitro via the canonical pathway. We further show that a mutant-secreted form of LRP5 can reduce bone thickness in mouse calvarial explant cultures. These data indicate that Wnt-mediated signaling via LRP5 affects bone accrual during growth and is important for the establishment of peak bone mass.

Adaptor Proteins, Signal Transducing↗
PubMed2001

Polymerization of the SAM domain of TEL in leukemogenesis and transcriptional repression.

TEL is a transcriptional repressor that is a frequent target of chromosomal translocations in a large number of hematalogical malignancies. These rearrangements fuse a potent oligomerization module, the SAM domain of TEL, to a variety of tyrosine kinases or transcriptional regulatory proteins. The self-associating property of TEL-SAM is essential for cell transformation in many, if not all of these diseases. Here we show that the TEL-SAM domain forms a helical, head-to-tail polymeric structure held together by strong intermolecular contacts, providing the first clear demonstration that SAM domains can polymerize. Our results also suggest a mechanism by which SAM domains could mediate the spreading of transcriptional repression complexes along the chromosome.

Amino Acid Sequence↗
PubMed2001

Are Noonan syndrome and Noonan-like/multiple giant cell lesion syndrome distinct entities?

We report on a family with typical clinical findings of Noonan syndrome associated with giant cell lesions in maxilla and mandible. We discuss the obvious clinical overlap between Noonan syndrome and Noonan-like/multiple giant cell lesion syndrome, and we give further clinical and molecular support that these two entities could be allelic conditions.

Adolescent↗
PubMed2001

Haploinsufficiency of the human homeobox gene ALX4 causes skull ossification defects.

Inherited defects of skull ossification often manifest as symmetric parietal foramina (PFM; MIM 168500). We previously identified mutations of MSX2 in non-syndromic PFM and demonstrated genetic heterogeneity. Deletions of 11p11-p12 (proximal 11p deletion syndrome, P11pDS; MIM 601224) are characterized by multiple exostoses, attributable to haploinsufficiency of EXT2 and PFM. Here we identify ALX4, which encodes a paired-related homeodomain transcription factor, as the PFM disease gene in P11pDS.

Animals↗
PubMed2000

Mutations of the gene encoding the transmembrane transporter protein ABC-C6 cause pseudoxanthoma elasticum.

We recently published the precise chromosomal localization on chromosome 16p13.1 of the genetic defect underlying pseudoxanthoma elasticum (PXE), an inherited disorder characterized by progressive calcification of elastic fibers in skin, eye, and the cardiovascular system. Here we report the identification of mutations in the gene encoding the transmembrane transporter protein, ABC-C6 (also known as MRP-6), one of the four genes located in the region of linkage, as cause of the disease. Sequence analysis in four independent consanguineous families from Switzerland, Mexico, and South Africa and in one non-consanguineous family from the United States demonstrated several different mis-sense mutations to cosegregate with the disease phenotype. These findings are consistent with the conclusion that PXE is a recessive disorder that displays allelic heterogeneity, which may explain the considerable phenotypic variance characteristic of the disorder.

ATP-Binding Cassette Transporters↗
PubMed2000

Cardiac findings in 31 patients with Noonan's syndrome.

OBJECTIVE: To evaluate cardiac findings in 31 Noonan syndrome patients. METHODS: Thirty-one (18 males and 13 females)patients from 26 families affected with Noonan's syndrome were evaluated from the cardiac point of view with electrocardiography and Doppler echocardiography. RESULTS: Twenty patients had some type of cardiac abnormality. The most frequent was pulmonary valve stenosis followed by hypertrophic myocardiopathy, commonly associated with valve defects. Upper deviation of the QRS axis was observed in 80% of these patients. CONCLUSION: In view of the high frequency and diversity of cardiac abnormalities present in Noonan syndrome, cardiac evaluation with electrocardiography and echocardiography should be performed in all patients diagnostically suspected of having this disease.

Adolescent↗
PubMed1999

CACP, encoding a secreted proteoglycan, is mutated in camptodactyly-arthropathy-coxa vara-pericarditis syndrome.

Altered growth and function of synoviocytes, the intimal cells which line joint cavities and tendon sheaths, occur in a number of skeletal diseases. Hyperplasia of synoviocytes is found in both rheumatoid arthritis and osteoarthritis, despite differences in the underlying aetiologies of the two disorders. We have studied the autosomal recessive disorder camptodactyly-arthropathy-coxa vara-pericarditis syndrome (CACP; MIM 208250) to identify biological pathways that lead to synoviocyte hyperplasia, the principal pathological feature of this syndrome. Using a positional-candidate approach, we identified mutations in a gene (CACP) encoding a secreted proteoglycan as the cause of CACP. The CACP protein, which has previously been identified as both 'megakaryocyte stimulating factor precursor' and 'superficial zone protein', contains domains that have homology to somatomedin B, heparin-binding proteins, mucins and haemopexins. In addition to expression in joint synovium and cartilage, CACP is expressed in non-skeletal tissues including liver and pericardium. The similarity of CACP sequence to that of other protein families and the expression of CACP in non-skeletal tissues suggest it may have diverse biological activities.

Amino Acid Sequence↗
PubMed1999

Effects of experimentally generated bull antisperm antibodies on in vitro fertilization.

To test the hypothesis that bull antisperm antibodies have the capacity to interfere with fertilization, antisperm antibodies were generated in three 13-mo-old Holstein bulls by auto-immunizing each bull with sperm three times. All bulls produced serum antisperm IgG1 and IgG2 antibodies. No serum antisperm IgA nor seminal plasma antisperm antibodies of any isotype could be detected by ELISA. Western blots were performed with immunopurified IgG1 and IgG2 from pre- and post-immunization sera from one test bull. Both post-immunization IgG1 and IgG2 recognized a 45-kDa sperm antigen. Serum samples from a normal bull stud population tested by ELISA had significantly higher levels of antisperm antibodies than did heifers. The bull stud serum samples giving the highest ELISA values differed from those of the immunized bulls in that their antisperm antibodies were of the IgM isotype only. Bull sperm were incubated with serum from the immunized and control bulls, then added to bovine oocytes in vitro. Incubation of sperm with post-immunization serum reduced in vitro fertilization rates (p < 0.01). This study demonstrated that antisperm IgG1 and IgG2 generated by sperm auto-immunizations reduced fertility in vitro, and therefore naturally occurring antisperm antibodies may affect fertility in bulls.

Animals↗