Clinical and Genetic Analysis of Multiple Osteochondromas in A Cohort of Argentine Patients.

Multiple Osteochondromatosis (MO, MIM 133700 & 133701), an autosomal dominant O-glycosylation disorder (EXT1/EXT2-CDG), can be associated with a reduction in skeletal growth, bony deformity, restricted joint motion, shortened stature and pathogenic variants in two tumor suppressor genes, EXT1 and EXT2. In this work, we report a cross-sectional study including 35 index patients and 20 affected family members. Clinical phenotyping of all 55 affected cases was obtained, but genetic studies were performed only in 35 indexes. Of these, a total of 40% (n = 14) had a family history of MO. Clinical severity scores were class I in 34% (n:18), class II in 24.5% (n:13) and class III in 41.5% (n:22). Pathogenic variants were identified in 83% (29/35) probands. We detected 18 (62%) in EXT1 and 11 (38%) in EXT2. Patients with EXT1 variants showed a height z-score of 1.03 SD lower than those with EXT2 variants and greater clinical severity (II-III vs. I). Interestingly, three patients showed intellectual impairment, two patients showed a dual diagnosis, one Turner Syndrome and one hypochondroplasia. This study improves knowledge of MO, reporting new pathogenic variants and forwarding the worldwide collaboration necessary to promote the inclusion of patients into future biologically based therapeutics.

Challenges in genetic diagnosis, co-occurrence of 22q11.2 deletion syndrome and Noonan syndrome.

Noonan syndrome (NS) is caused by pathogenic variants in genes involved in the RAS/MAPK pathway. On the other hand, 22q11.2 Deletion Syndrome (22q11.2DS) is caused by heterozygous microdeletion on chromosome 22q11.2. The clinical characteristics of both syndromes are expected to be relatively distinct, and, in fact, there is only one report of these syndromes occurring together, but on daily clinical practice and especially in early childhood phenotypes may overlap. In this study, we describe a patient with NS and 22q11.2DS features harboring a heterozygous 2.54 Mb deletion of chromosome 22q11.2 and a variant in LZTR1, c.1531G > A p.(Val511Met). In 1993, Wilson et al reported a patient with both 22q11.2DS and NS, proposing that probably more than one gene is deleted in the proband and that one of the deleted genes is responsible for Noonan's phenotype. In our patient, one of the deleted genes within the 22q11.2 region was the LZTR1 gene which was associated with NS in 2015. This case also highlights the importance of the long-term patients' follow-up to detect evolutionary changes that may appear in the phenotype and alerts clinicians of the co-occurrence of two syndromes that may manifest over time.

Clinical and molecular characterization of mitochondrial DNA disorders in a group of Argentinian pediatric patients.

OBJECTIVE: To describe the clinical and molecular features of a group of Argentinian pediatric patients with mitochondrial DNA (mtDNA) disorders, and to evaluate the results of the implementation of a classical approach for the molecular diagnosis of mitochondrial diseases. METHODS: Clinical data from 27 patients with confirmed mtDNA pathogenic variants were obtained from a database of 89 patients with suspected mitochondrial disease, registered from 2014 to 2020. Clinical data, biochemical analysis, neuroimaging findings, muscle biopsy and molecular studies were analyzed. RESULTS: Patients were 18 females and 9 males, with ages at onset ranging from 1 week to 14 years (median = 4 years). The clinical phenotypes were: mitochondrial myopathy, encephalopathy, lactic acidosis, and stroke-like episodes (MELAS) syndrome (n = 11), Leigh syndrome (n = 5), Kearns-Sayre syndrome (n = 3), Chronic Progressive External Ophthalmoplegia (n = 2), Leber hereditary optic neuropathy (n = 2), myoclonic epilepsy associated with ragged-red fibers (n = 1) and reversible infantile myopathy with cytochrome-C oxidase deficiency (n = 3). Most of the patients harbored pathogenic single nucleotide variants, mainly involving mt-tRNA genes, such as MT-TL1, MT-TE and MT-TK. Other point variants were found in complex I subunits, like MT-ND6, MT-ND4, MT-ND5; or in MT-ATP6. The m.13513G > A variant in MT-ND5 and the m.9185 T > C variant in MT-ATP6 were apparently de novo. The rest of the patients presented large scale-rearrangements, either the "common" deletion or a larger deletion. CONCLUSIONS: This study highlights the clinical and genetic heterogeneity of pediatric mtDNA disorders. All the cases presented with classical phenotypes, being MELAS the most frequent. Applying classical molecular methods, it was possible to achieve a genetic diagnosis in 30% of the cases, suggesting that this is an effective first approach, especially for those centers from low-middle income countries, leaving NGS studies for those patients with inconclusive results.

Contribution of Mitochondrial DNA Heteroplasmy to the Congenital Cardiac and Palatal Phenotypic Variability in Maternally Transmitted 22q11.2 Deletion Syndrome.

Congenital heart disease (CHD) and palatal anomalies (PA), are among the most common characteristics of 22q11.2 deletion syndrome (22q11.2DS), but they show incomplete penetrance, suggesting the presence of additional factors. The 22q11.2 deleted region contains nuclear encoded mitochondrial genes, and since mitochondrial function is critical during development, we hypothesized that changes in the mitochondrial DNA (mtDNA) could be involved in the intrafamilial variability of CHD and PA in cases of maternally inherited 22q11.2DS. To investigate this, we studied the transmission of heteroplasmic mtDNA alleles in seventeen phenotypically concordant and discordant mother-offspring 22q11.2DS pairs. We sequenced their mtDNA and identified 26 heteroplasmic variants at >1% frequency, representing 18 transmissions. The median allele frequency change between a mother and her child was twice as much, with a wider distribution range, in PA discordant pairs, p-value = 0.039 (permutation test, 11 concordant vs. 7 discordant variants), but not in CHD discordant pairs, p-value = 0.441 (9 vs. 9). Only the variant m.9507T>C was considered to be pathogenic, but it was unrelated to the structural phenotypes. Our study is novel, yet our results are not consistent with mtDNA variation contributing to PA or CHD in 22q11.2DS. Larger cohorts and additional factors should be considered moving forward.

Noonan syndrome with loose anagen hair with variants in the PPP1CB gene: First familial case reported.

Rasopathies are a group of phenotypically overlapping conditions that include Noonan, Noonan with multiple lentigines, Noonan with loose anagen hair, Costello, Cardio-facio-cutaneous, and Neurofibromatosis-Noonan syndromes. Noonan syndrome with loose anagen hair (NS-LAH) is clinically characterized by prominent forehead, macrocephaly, growth hormone deficiency, sparse, loose and slow-growing anagen hair, hyperpigmented skin with eczema or ichthyosis, mild psychomotor delays, hypernasal voices, and attention deficit hyperactivity disorder. Variants in SHOC2 are responsible for the majority of the cases. Gripp et al. identified four unrelated individuals with similar phenotype to NS-LAH with pathogenic variants in PPP1CB. In this study, we present one family and one patient with NS-LAH and variants in PPP1CB. The first patient belongs to a family with a likely pathogenic variant, c.545T>A (p.Met182Lys), the first family published so far with a variant in this gene. The second patient harbors a de novo pathogenic variant, c.146C>G (p.Pro49Arg). This study presents two additional patients with this rare syndrome in order to increase the clinical characterization of the syndrome and provide more evidence of the pathogenicity of the c.545T>A (p.Met182Lys) variant in PPP1CB, a gene recently associated with NS-LAH.

Ehlers-Danlos Syndrome: Molecular and Clinical Characterization of TNXA/TNXB Chimeras in Congenital Adrenal Hyperplasia.

CONTEXT: The syndrome CAH-X is due to a contiguous gene deletion of CYP21A2 and TNXB resulting in TNXA/TNXB chimeras. OBJECTIVE: To analyze TNXB gene status and to clinically evaluate the Ehlers-Danlos syndrome phenotype in a large cohort of Argentine congenital adrenal hyperplasia (CAH) patients to assess the prevalence of this condition in our population. METHODS: TNXB gene analysis was performed in 66 nonrelated CAH patients that were carriers of the CYP21A2 gene deletion. A molecular strategy based on multiplex ligation-dependent probe amplification and Sanger sequencing analysis was developed allowing for the detection of different, previously described TNXA/TNXB chimeras, named CH1, CH2, and CH3. The main outcome measures were TNXB status of CAH patients that were carriers of the CYP21A2 deletion in the homozygous or heterozygous state. RESULTS: TNXA/TNXB CH1 was found in 41%, CH2 in 29%, and CH3 in 1% of nonrelated alleles carrying the CYP21A2 deletion. Thus, overall 71% of alleles were found to carry a contiguous gene deletion. Sixty-seven percent of patients analyzed had a monoallelic form and 6% a biallelic form. All patients with the biallelic form had severe skin hyperextensibility and generalized joint hypermobility. CONCLUSION: Based on the high frequency of TNXB alterations found in CYP21A2 deletion carrier alleles, we recommend evaluating TNXB status in these patients, and assessing connective tissue dysplasia, including cardiologic alterations in positive cases. The number of patients undergoing cardiological evaluation should be expanded to determine the incidence of structural and functional abnormalities in this cohort.

Clinical and Radiologic Evaluation of an Individual with Hypochondroplasia and a Novel FGFR3 Mutation.

Hypochondroplasia (HCH), a skeletal dysplasia caused by mutations in the fibroblast growth factor receptor 3 ( FGFR3 ) gene, is characterized by disproportionate short stature. The p.Asn540Lys (p.N540K) mutation accounts for ∼50 to 70% of cases of HCH, but novel FGFR3 mutations are described. We present a family with disproportionately short stature and mild radiologic findings seen in a major public pediatric hospital in Argentina. A previously undescribed heterozygous missense variant in FGFR3, NM_000142.4:667C > T; p.(Arg223Cys) was identified. The predicted phenotype correlates well with the mild auxologic and radiologic characteristics observed. In this case, disproportionately short stature raised the suspicion of skeletal dysplasia.

Providing more evidence on LZTR1 variants in Noonan syndrome patients.

Noonan syndrome (NS, OMIM 163950) is a common autosomal dominant RASopathy caused mainly by gain-of-function germline pathogenic variants in genes involved in the RAS/MAPK signaling pathway. LZTR1 gene has been associated with both dominant and recessive NS. Here, we present seven patients with NS and variants in the LZTR1 gene from seven unrelated families, 14 individuals in total. The detection rAte of LZTR1 variants in our NS cohort was 4% similar to RAF1 and KRAS genes, indicating that variants in this gene might be frequent among our population. Three different variants were detected, c.742G>A (p.Gly248Arg), c.360C>A (p.His120Gln), and c.2245T>C (p.Tyr749His). The pathogenic variant c.742G>A (p.Gly248Arg) was found in five/seven patients. In our cohort 50% of patients presented heart defects and neurodevelopment delay or learning disabilities, short stature was present in 21% of them and one patient had acute lymphoblastic leukemia. This study broadens the spectrum of variants in the LZTR1 gene and provides increased knowledge of the clinical phenotypes observed in Argentinean NS patients.

SHOX Deficiency in Argentinean Cohort: Long-Term Auxological Follow-Up and a Family's New Mutation.

A cohort study on the growth of 19 Argentinean children, aged 0 to 18 years, and 11 of their first-degree relatives with alterations in the SHOX gene or its regulatory regions is reported. Children are born shorter and experience a growth delay during childhood with a stunted pubertal growth spurt. Body disproportion, with a sitting height/height ratio above +2 standard deviation score (SDS), was already present as early as 2 years old. Hand length was normal. Shortening of the radius, with a length below -1.9 SDS, was the earliest and most frequent radiological sign detected as early as 45 days old. We found a previously unreported mutation in a family with a highly variable phenotype, the boy had a severe phenotype with a milder presentation in other affected members of the family. We conclude that body disproportion and a shorter radius length on X-ray are useful tools for selecting children to undergo SHOX molecular studies.

Novel IFT122 mutations in three Argentinian patients with cranioectodermal dysplasia: Expanding the mutational spectrum.

Cranioectodermal dysplasia (CED), also known as Sensenbrenner syndrome, is an autosomal recessive ciliary chondrodysplasia characterized by a recognizable craniofacial gestalt, skeletal abnormalities, and ectodermal features. To date, four genes have been shown to underlie the syndrome, namely, IFT122 (WDR10), WDR35 (IFT121), IFT43 (C14orf179), and WDR19 (IFT144). Clinical characterization of a larger cohort of patients with CED has been undertaken previously. Nevertheless, there are too few molecularly confirmed patients reported in the literature to determine precise genotype-phenotype correlations. To date, biallelic IFT122 mutations have been described in only five families. We therefore studied three unrelated Argentinian patients with typical features of CED using a 4813 next-generation sequencing (NGS) gene panel, which we call the "Mendeliome." The three patients had different, novel, compound heterozygous mutations in IFT122. Consequently, we compared these three patients to those previously described with IFT122 mutations. Thus, our report serves to add 6 novel mutations to the IFT122 mutation spectrum and to contribute to the IFT122-related clinical characterization.

[Partial duplication of chromosome 4 in a patient with bilateral ocular coloboma]. / Duplicación parcial del cromosoma 4 asociada con coloboma ocular bilateral.

Partial trisomy 4q is a rare chromosomal disease. It involves duplication of a portion (particularly the distal one) of the long arm of chromosome 4. In most cases results from a balanced translocation on one single progenitor. The "de novo" appearance is less common. Depending on the size and location of duplicated genetic material, patients may have different clinical manifestations. Associated eye pathology has been scarcely informed. We report on a novel case of a male infant with a proximal "de novo" 4q12-q22 duplication and bilateral iris, retinal and optic nerve coloboma.

Duplicación parcial del cromosoma 4 asociada con coloboma ocular bilateral / Partial duplication of chromosome 4 in a patient with bilateral ocular coloboma

La trisomía parcial 4q es una enfermedad cromosómica rara causada por la duplicación de una porción (comúnmente la distal) del brazo largo del cromosoma 4. En la mayoría de los casos resulta de una translocación balanceada de uno de los progenitores, siendo menos frecuente la aparición de novo. Los pacientes presentan diversas características clínicas según el tamaño y sitio específico de la región comprometida. Su asociación con patologías oculares ha sido escasamente comunicada. Presentamos el primer caso de un paciente pediátrico de sexo masculino con una duplicación parcial de novo del segmento proximal del brazo largo del cromosoma 4 (4q12-q22) y coloboma bilateral de iris, retina y nervio óptico.

Partial trisomy 4q is a rare chromosomal disease. It involves duplication of a portion (particularly the distal one) of the long arm of chromosome 4. In most cases results from a balanced translocation on one single progenitor. The "de novo" appearance is less common. Depending on the size and location of duplicated genetic material, patients may have different clinical manifestations. Associated eye pathology has been scarcely informed. We report on a novel case of a male infant with a proximal "de novo" 4q12-q22 duplication and bilateral iris, retinal and optic nerve coloboma.

Duplicación parcial del cromosoma 4 asociada con coloboma ocular bilateral / Partial duplication of chromosome 4 in a patient with bilateral ocular coloboma

La trisomía parcial 4q es una enfermedad cromosómica rara causada por la duplicación de una porción (comúnmente la distal) del brazo largo del cromosoma 4. En la mayoría de los casos resulta de una translocación balanceada de uno de los progenitores, siendo menos frecuente la aparición de novo. Los pacientes presentan diversas características clínicas según el tamaño y sitio específico de la región comprometida. Su asociación con patologías oculares ha sido escasamente comunicada. Presentamos el primer caso de un paciente pediátrico de sexo masculino con una duplicación parcial de novo del segmento proximal del brazo largo del cromosoma 4 (4q12-q22) y coloboma bilateral de iris, retina y nervio óptico.(AU)

Partial trisomy 4q is a rare chromosomal disease. It involves duplication of a portion (particularly the distal one) of the long arm of chromosome 4. In most cases results from a balanced translocation on one single progenitor. The "de novo" appearance is less common. Depending on the size and location of duplicated genetic material, patients may have different clinical manifestations. Associated eye pathology has been scarcely informed. We report on a novel case of a male infant with a proximal "de novo" 4q12-q22 duplication and bilateral iris, retinal and optic nerve coloboma.(AU)

Prevalencia de la patología genética en pacientes pediátricos internados en un hospital de alta complejidad / Prevalence of genetic pathology in pediatric patients admitted to a tertiary-care hospital

Las enfermedades genéticas son aquellas perturbaciones del estado de la salud en las que intervienen en mayor o menor medida alteraciones de la constitución genética. En algunos casos la constitución genética es claramente determinante de una condición clínica, en otros casos en cambio solo será determinada la susceptibilidad que, en concurrencia con otros factores, predisponen al desarrollo de enfermedades. Los objetivos principales de este trabajo se centraron en analizar como la presencia de patología genética influye en la morbimortalidad de los pacientes hospitalizados evaluando los egresos del año 2007 en el Hospital Juan P. Garrahan, determinar qué porcentaje de pacientes pediátricos egresados de un centro de referencia presentan patología total o parcialmente genética, describir sus características y la carga asistencial que representan. Se realizó un estudio retrospectivo, descriptivo, transversal. Se revisaron 2300 historias clínicas (HC) correspondientes a los egresos del año 2007 en cinco salas de internación: Neonatología, CIM 64, 32, 62 y 73. En las salas se comparó: 1-porcentaje de pacientes con y sin patología genética, 2- días requeridos en una internación entre pacientes con y sin patología genética. 3- reinternaciones. 4- tipo de egreso. En las cinco salas analizadas se observó una mayor prevalencia de patologías total o parcialmente genéticas, en relación a la patología no genética. Analizando la morbimortalidad mediante días de internación requeridos en la hospitalización y número de reinternaciones, se observó que en tres de las cinco salas los días de internación requeridos eran mayores en los pacientes con patología total o parcialmente genética.

Genetic diseases are disorders affecting health in which al-terations in the genetic constitution intervene to a greater or lesser extent. In some cases the genetic constitution clearly determines a clinical condition, in others, however, it merely de-termines a susceptibility which, in association with other factors, predisposes to the development of a certain disease. The aims of this study were to analyze the impact of genetic pathology on the morbidity and mortality of hospitalized patients evalu-ating children discharged from the Juan P. Garrahan Hospital in 2007, to the determine the percentage of pediatric patients discharged from a tertiary care center who presented with a total or partial genetic pathology, to describe their features and the burden of care they represented. A retrospective, descrip-tive, cross-sectional study was conducted. We reviewed 2300 clinical charts (CC) of children discharged from different five wards in 2007: Neonatology and wards 64, 32, 62, and 73. We compared: 1- percentage of patients with and without genetic pathology, 2- days of hospital stay of patients with and with-out genetic pathology, 3- readmissions, 4- type of discharge. On all wards a higher prevalence of totally or partially genetic pathologies than of non-genetic pathologies was found. When comparing morbidity and mortality with days of hospital stay and number of readmissions, we found that in three of five wards days of hospital stay were increased in patients with total or partially genetic pathologies.

Oral-facial-digital syndrome gabrielli type: second report.

We describe a second sporadic case, a girl, with the features of Oral-Facial-Digital, type Gabrielli. We comment on several aspects of this condition and confirm this entity as a unique syndrome, different from the other OFDS. To date, the diagnosis is based only on clinical and radiographic findings.

Disostosis acrofacial (Síndrome de Nager) / Acrofacial dysostosis (Nager syndrome)

Se describe una niña que presenta las características del síndrome de Nager, que consisten principalmente en una disostosis mandibulofacial con anomalías radiales. La mayoría de los casos son esporádicos pero hay evindencias que sugieren herencia monogénica. El diagnóstico prenatal ecográfico puede ser útil.