Jaime Toral-López

Familial Pycnodysostosis: Identification of a Novel Mutation in the CTSK Gene (Cathepsin K)

Background Pycnodysostosis, an autosomal recessive skeletal dysplasia, is characterized by short stature, osteosclerosis, delayed cranial suture closure, hypoplastic mandible, acro-osteolysis, hypoplastic clavicle, and dental anomalies. The disorder is caused by CTSK gene defects, a gene localized on 1q21. Purpose To describe the clinical, radiological, and molecular findings in a family with pycnodysostosis. Methods The CTSK gene was analyzed from genomic DNA in a nonconsanguinity Mexican family with 3 affected members with pycnodysostosis and 100 healthy controls. Results and Interpretation We identified the novel homozygous mutation c.908G>A within exon 8 of the CTSK gene. This missense mutation leads to the substitution of the amino acid glycine at position 303 by glutamic acid (G303E) in cathepsin K protease. No genotype/phenotype correlation was present in affected members of the family with pycnodysostosis.

ADRB1 and ADBR2 gene polymorphisms and the ocular hypotensive response to topical betaxolol in healthy Mexican subjects.

Abstract Background: The β adrenergic receptors (ADRB) are expressed in the ciliary body and trabecular meshwork, structures involved in aqueous humor production and outflow, respectively. ADRB are members of the adrenergic family of G-protein-coupled receptors. Topic β blockers have a good local and systemic tolerance; they reduce the aqueous humor production and eye strain blocking the ADRB of the ciliary body and interfering with adenylate cyclase. However, the ocular hypotensive response is not the same in all patients and could be mediated by the polymorphisms of the ADRB genes. Materials and methods: Seventy-two healthy subjects were studied after treatment with topical betaxolol in both eyes. We analyzed ADRB1 and ADRB2 gene polymorphisms by PCR and automated DNA sequencing. Results: There was statistically significant difference between baseline intraocular pressure (IOP) and final IOP of both eyes (baseline IOP 16.2 ± 1.2 – follow-up IOP 13.6 ± 2.0 (mean difference–2.5 ± 1.3, p < 0.001). Gly389 had a higher baseline IOP than Arg389 (17.0 ± 1.2 mmHg versus 16.0 ± 1.2 mmHg; p = 0.02), and conversely Arg389 had a greater magnitude of response than Gly389 to betaxolol therapy (−2.9 ± 1.1 mmHg versus −0.7 ± 0.4 mmHg; p < 0.001). Gln27 had a higher response than Glu27 (−2.7 ± 1.3 mmHg versus −1.9 ± 1.0; p = 0.02). Conclusion: Arg389 polymorphism of the ADRB1 gene and Gln27 polymorphism of the ADRB2 gene were associated with the hypotensive response to topic betaxolol in healthy Mexican volunteers.

Complete monosomy mosaic of chromosome 21: Case report and review of literature

Complete monosomy mosaic of chromosome 21 is a rare disorder. The syndromic features are highly variable. This study describes a girl of Mexican origin with complete monosomy 21 in mosaicism with novel findings, including cortical atrophy, macrostomia, pectum excavatum and immune deficiencies. Parental karyotypes were normal. FISH analysis with probes from 21q22.1-q22.2 region and centromere of X DNA probe was performed on peripheral blood lymphocytes whereas 21q22.1-q22.2 and 21q, 4p, 4q subtelomeric DNA probes were tested in fibroblasts. We propose that the monosomy 21 mosaicism is the cause of the survival of children with more than 4 months of age.

An intellectually disabled patient with the 5q14.3q15 microdeletion syndrome associated with an apparently de novo t(2;5)(q13;q14)

An Intellectually Disabled PatientWith the 5q14.3q15 Microdeletion Syndrome Associated With an Apparently De Novo t(2;5)(q13;q14) Jaime Toral-L opez, Beatriz Buentello-Volante, Marta M. Balderas-Minor, Carmen Amezcua-Herrera, Juan M. Valdes-Miranda, Luz Ma. Gonz alez-Huerta, Marco Gudi~no, Sergio A. Cuevas-Covarrubias, and Juan Carlos Zenteno* Department of Genetics, Centro M edico Ecatepec, ISSEMYM, Mexico, Mexico Department of Genetics-Research Unit, Institute of Ophthalmology ‘‘Conde de Valenciana’’ Mexico City, Mexico Department of Neuropediatrics, Centro M edico Ecatepec, ISSEMYM, Mexico, Mexico Nuclear Magnetic Resonance service, Hospital General de M exico, Mexico City, Mexico Department of Genetics, Hospital General de M exico, Faculty of Medicine, UNAM, Mexico City, Mexico Department of Experimental Medicine, UNAM, Mexico City, Mexico Department of Biochemistry, Faculty of Medicine, National Autonomous University of Mexico (UNAM), Mexico City, Mexico

A Novel 23.1 Mb Interstitial Deletion Involving 7q22.3q32.1 in a Girl with Short Stature, Motor Delay, and Craniofacial Dysmorphism

Interstitial deletions of 7q show a wide phenotypic spectrum that varies with respect to the location and size of the deleted region. They lead to craniofacial dysmorphism with intellectual disability, growth retardation, and various congenital defects. Here, a Mexican girl with microcephaly, facial dysmorphism, short stature, hand anomalies, and intellectual disability was analyzed by CytoScan HD array. Her phenotype was associated with a de novo 7q22.3q32.1 deletion involving 109 loci, 57 of them listed in the OMIM database. This novel deletion increases the knowledge of the variability in the rupture sites of the region and expands the spectrum of molecular and clinical defects of the 7q deletion syndrome.

A novel microdeletion involving the 13q31.3–q32.1 region in a patient with normal intelligence

Microdeletions of the long arm of chromosome 13 lead to a characteristic facial appearance with systemic affection; 13q deletion shows a wide phenotypic spectrum that varies with respect to the location and size of the deletion region. The main clinical features are mental retardation, growth retardation, craniofacial dysmorphy and various congenital defects. In the present study we describe the case of an adult female of Mexican origin with microcephaly, facial dysmorphism, short stature, hand anomalies and normal intelligence associated with a de novo 13q31.3-q32.1 microdeletion that involved several genes including the MIR17HG and the GPC5 genes.

A CRYGC gene mutation associated with autosomal dominant pulverulent cataract.

PURPOSE To describe at molecular level a family with pulverulent congenital cataract associated with a CRYGC gene mutation. METHODS One family with several affected members with pulverulent congenital cataract and 230 healthy controls were examined. Genomic DNA from leukocytes was isolated to analyze the CRYGA-D cluster, CX46, CX50 and MIP genes through high-resolution melting curve and DNA sequencing. RESULTS DNA sequencing in the affected members revealed the c.143G>A mutation (p.R48H) in exon 2 of the CRYGC gene; 230 healthy controls and ten healthy relatives were also analyzed and none of them showed the c.143G>A mutation. No other polymorphisms or mutations were found to be present. CONCLUSION In the present study, we described a family with pulverulent congenital cataract that segregated the c.143G>A mutation (p.R48H) in the CRYGC gene. A few mutations have been described in the CRYGC gene in autosomal dominant cataract, none of them with pulverulent cataract making clear the clinical heterogeneity of congenital cataract. This mutation has been associated with the phenotype of congenital cataract but also is considered an SNP in the NCBI data base. Our data and previous report suggest that p.R48H could be a disease-causing mutation and not an SNP.

Whole Exome Sequencing Reveals a Mutation in CRYBB2 in a Large Mexican Family with Autosomal Dominant Pulverulent Cataract

Congenital cataract, an important cause of reversible blindness, is due to several causes including Mendelian inheritance. Thirty percent of cataracts are hereditary with participation of the gamma crystallin genes. Clinical and genetic heterogeneity is observed in patients with gene mutations and congenital cataract; about 40 genetic loci have been associated with hereditary cataract. In this study, we identified the underlying genetic cause of an autosomal dominant pulverulent cataract (ADPC) in a large Mexican family. Twenty-one affected patients and 20 healthy members of a family with ADPC were included. Genomic DNA was analyzed by whole exome sequencing in the proband, a normal daughter, and in an affected son, whereas DNA Sanger sequencing was performed in all members of the family. After the bioinformatics analysis, all samples were genotyped using Sanger sequencing to eliminate variants that do not cosegregate with the cataract. We observed a perfect cosegregation of a nonsense mutation c.475C>T (p.Q155*) in exon 6 of the CRYBB2 gene with ADPC. We calculated a logarithm of the odds score of 5.5. This mutation was not detected in healthy members of the family and in 100 normal controls. This is the first Mexican family with ADPC associated with a p.Q155* mutation. Interestingly, this specific mutation in the CRYBB2 gene seems to be exclusively associated with pulverulent/cerulean cataract (with some clinical variability) independent of the populations genetic background.

Familial Blau syndrome without uveitis caused by a novel mutation in the nucleotide-binding oligomerization domain-containing protein 2 gene with good response to infliximab

The proband in this study was a 4‐year‐old Mexican girl with Blau syndrome. She and her affected family members had skin rash and arthritis but no uveitis. Exome sequencing and DNA direct sequencing from blood samples revealed a novel nucleotide‐binding oligomerization domain‐containing protein 2 gene mutation in the affected family members. This study is the first report of a Mexican family with Blau syndrome showing good infliximab treatment response. The novel mutation in the nucleotide‐binding oligomerization domain‐containing protein 2 gene (c.1808A>G) enriches the mutation spectrum in Blau syndrome. This family represents one of the few cases of autosomal Blau syndrome with no uveitis; because of phenotype variability, it is important to recognize Blau syndromes clinical spectrum and recommend genetic consultation.

A Family with Craniofrontonasal Syndrome and a Mutation (p.G151S) in the EFNB1 Gene: Expanding the Phenotype.

Craniofrontonasal syndrome (CFNS) is a rare genetic entity with X-linked dominant inheritance. CFNS is due to mutations in the Ephrin-B1 (EFNB1) gene. It is characterized by brachycephaly, frontonasal dysplasia, palate/lip defects, dental malocclusion, short neck, split nails, syndactyly, toe and finger defects, and minor skeletal defects. Intelligence is usually unaffected. CFNS exhibits unexpected manifestations between males and females as the latter are more affected. Cellular or metabolic interference due to X inactivation explains the more severe phenotype in heterozygous females. One family with several members affected with CFNS and 100 healthy controls were examined. DNA from leukocytes was isolated to analyze the EFNB1 gene. We did molecular modeling to assess the impact of the mutation on the EFNB1-encoded protein. DNA sequencing analysis of the EFNB1 gene of the affected members showed the heterozygous missense mutation c.451G>A in the EFNB1 gene (GRcH38, chrX: 68,839,708; GERP score in hg38 of 9.961). This transition mutation resulted in the substitution of Gly at position 151 by Ser. Analysis of the healthy members of the family and 100 unrelated controls showed a normal sequence of the EFNB1 gene. Phenotypes of the patients in this family differ from the classical CFNS due to the decreased size of sulci and fissures, subarachnoid space and ventricles, and the absence of a cleft lip/palate.