New Genetic Variants of RUNX2 in Mexican Families Cause Cleidocranial Dysplasia.

Cleidocranial dysplasia (CCD) is an autosomal dominant skeletal dysplasia characterized by persistent open skull sutures with bulging calvaria, hypoplasia, or aplasia of clavicles permitting abnormal opposition of the shoulders; wide public symphysis; short middle phalanx of the fifth fingers; and vertebral, craniofacial, and dental anomalies. It is a rare disease, with a prevalence of 1-9/1,000,000, high penetrance, and variable expression. The gene responsible for CCD is the Runt-related transcription factor 2 (RUNX2) gene. We characterize the clinical, genetic, and bioinformatic results of four CCD cases: two cases within Mexican families with six affected members, nine asymptomatic individuals, and two sporadic cases with CCD, with one hundred healthy controls. Genomic DNA analyses of the RUNX2 gene were performed for Sanger sequencing. Bioinformatics tools were used to predict the function, stability, and structural changes of the mutated RUNX2 proteins. Three novel heterozygous mutations (c.651_652delTA; c.538_539delinsCA; c.662T>A) and a previously reported mutation (c.674G>A) were detected. In silico analysis showed that all mutations had functional, stability-related, and structural alterations in the RUNX2 protein. Our results show novel mutations that enrich the pool of RUNX2 gene mutations with CCD. Moreover, the proband 1 presented clinical data not previously reported that could represent an expanded phenotype of severe expression.

Recurrent Mutation (p.Arg718Pro) in the COMP Gene with Clinical Heterogeneity of Pseudoachondroplasia.

Introduction: Pseudoachondroplasia (PSACH) and multiple epiphyseal dysplasia (MED) are allelic and caused by mutations in the COMP gene. Other mutations in the genes MMP13, AIFM1, B3GALT6, MATN3, COL9A1, COL9A2, COL9A3, and SLC26A2 have also been associated with evidence of dysplasia in the epiphysis, metaphysis, and spine. Case Presentation: We report on the first Mexican patient diagnosed with PSACH. The diagnosis was confirmed by identifying a recurrent heterozygous mutation c.2153G>C (p.Arg718Pro) in the COMP gene using whole-exome sequencing. Discussion: The anterior spindle-shaped vertebral bodies and severe short stature are not observed in patients carrying p.Arg718Pro, identifying another amino acid site associated with clinical heterogeneity. Reporting new cases with clinical heterogeneity in terms of phenotype plays a crucial role in understanding PSACH and MED pathogenesis. The most important aspect of this presentation is providing a new perspective on a recognized clinical scenario, thus setting the standard for better genetic counseling.

Psychiatric symptoms in an adolescent reveal a novel compound heterozygous mutation of the PANK2 gene in the atypical PKAN syndrome.

The proband in this study was a 16-year-old Mexican girl with psychotic and dyskinetic symptoms, and brain MRI showed at the basal ganglia the 'eye-of-the-tiger' sign. DNA direct sequencing identified a novel compound heterozygous mutation in the PANK2 gene. The diagnosis of pantothenate kinase-associated neurodegeneration (PKAN) disorder was made. This novel change increases the pool of PANK2 mutations. It supports the published data suggesting that PANK2 plays a significant role in patients expressing psychiatric phenotypes in the PKAN syndrome. When a patient presents with dyskinesia and psychiatric symptoms, PANK2 should be investigated as a possible diagnosis, and genetic consultation should be recommended.

Submicroscopic 11p13 deletion including the elongator acetyltransferase complex subunit 4 gene in a girl with language failure, intellectual disability and congenital malformations: A case report.

BACKGROUND: We described the main features of an infant diagnosed with facial dysmorphic, language failure, intellectual disability and congenital malformations to strengthen our understanding of the disease. Currently, treatment is only rehabilitation and surgery for cleft lip and palate. CASE SUMMARY: The proband was a 2-years-8-months-old girl. Familial history was negative for congenital malformations or intellectual disability. The patient had microcephaly, upward-slanting palpebral fissures, depressed nasal bridge, bulbous nose and bilateral cleft lip and palate. Brain magnetic resonance imaging showed cortical atrophy and band heterotopia. Her motor and intellectual development is delayed. A submicroscopic deletion in 11p13 involving the elongator acetyltransferase complex subunit 4 gene (ELP4) and a loss of heterozygosity in Xq25-q26.3 were detected. CONCLUSION: There is no treatment for the ELP4 deletion caused by a submicroscopic 11p3 deletion. We describe a second case of deletion of the ELP4 gene without aniridia, which confirms the association between ELP4 gene with several defects and absence of this ocular defect. Additional clinical data in the deletion of the ELP4 gene as cleft palate, facial dysmorphism, and changes at level brain could be associated to this gene or be part of the effect of the recessives genes involved in the loss of heterozygosity region of Xq25-26.3.

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 syndrome's clinical spectrum and recommend genetic consultation.

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 population's genetic background.

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.

Jacobsen Syndrome: Surgical Complications due to Unsuspected Diagnosis, the Importance of Molecular Studies in Patients with Craniosynostosis.

Jacobsen syndrome (JBS) is an uncommon contiguous gene syndrome. About 85-92% of cases have a de novo origin. Clinical variability and severity probably depend on the size of the affected region. The typical clinical features in JBS include intellectual disability, growth retardation, craniofacial dysmorphism as well as craniosynostosis, congenital heart disease, and platelet abnormalities. The proband was a 1 year/3-month-old Mexican male. Oligonucleotide-SNP array analysis using the GeneChip Human Cytoscan HD was carried out for the patient from genomic DNA. The SNP array showed a 14.2-Mb deletion in chromosome 11q23.3q25 (120,706-134,938 Mb), which involved 163 RefSeq genes in the database of genomic variation. We report a novel deletion in JBS that increases the knowledge of the variability in the mutation sites in this region and expands the spectrum of molecular and clinical defects in this syndrome.

Two novel compound heterozygous families with a trimutation in the GJB2 gene causing sensorineural hearing loss.

BACKGROUND: Sensorineural hearing loss (SNHL) is a genetically heterogeneous disease. GJB2 gene mutations seem to be the most frequent cause of hereditary hearing impairment in several populations. There is variability in the mutations in the GJB2 gene worldwide; this remarks the influence of ethnic background in SNHL. OBJECTIVE: To describe the presence of two trimutations in the GJB2 gene in two Mexican families with hereditary SNHL. MATERIALS AND METHODS: Two unrelated Mexican families with prelingual SNHL were included in the study. Analysis of the GJB2 gene through PCR and DNA direct sequencing analysis was performed in all members of the families and in 100 normal controls. RESULTS: Affected member of the family 1 showed the trimutation p.S19R/p.R32S/p.E47*, whereas affected members of the family 2 showed the trimutation p.F31I/p.W44*/p.V84M. Parents of both families were heterozygous with normal audition. CONCLUSION: We found a novel mutation in the GJB2 gene and two trimutations with SNHL not previously reported. This remarks the complexity in the pattern of mutations in the GJB2 gene in SNHL and enriches the spectrum of the type of molecular defects in the GJB2 gene.

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.

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

BACKGROUND: The ß 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 ß 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.

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.

Cerebral hemihypoplasia and nevus flammeus in a child with oromandibular limb hypogenesis syndrome type III.

Oromandibular limb hypogenesis syndrome (OMLH; OMIM 103300) encompasses a group of uncommon disorders characterized by malformations in the mouth, jaw and limbs. It has been associated with various entities such as gastroschisis, pulmonary hypoplasia, intestinal atresia, renal agenesis, hydrocephalus and other syndromes. We describe a boy of Mexican origin with features of OMLH. In addition, brain magnetic resonance imaging shows cerebral hemiatrophy and hemihypoplasia and an ipsilateral arachnoid cyst, as well as microcephaly and frontal nevus flammeus were observed. This association, to the best of our knowledge, has not been previously reported in the literature and could be part of a same spectrum of vascular defect with OMLH.

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.

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.