Genetic analysis of osteogenesis imperfecta in a large Brazilian cohort

INTRODUCTION

Osteogenesis imperfecta (OI) is a genetically and clinically heterogeneous disorder caused by disruption of type I collagen synthesis. Previous Brazilian molecular OI studies have been restricted to case reports or small cohorts. The Brazilian OI Network (BOIN) is a multicenter study collecting clinical OI treatment data from five reference centers in three regions of Brazil.

OBJECTIVE

To describe the molecular analysis of a large cohort of OI registered at BOIN.

METHODS

Targeted next-generation sequencing (NGS) was performed at a centralized laboratory with the Ion Torrent platform, covering 99.6 % of the coding regions of 18 OI-associated genes. Clinical information was obtained from a clinical database.

RESULTS

We included 156 subjects in the molecular analyses. Variants were detected in 121 subjects: 65 (53.7 %) in COL1A1, 42 (34.7 %) in COL1A2, 2 (1.7 %) in IFITM5, one (0.8 %) in CRTAP, three (2.5 %) in P3H1, two (1.7 %) in PPIB, four (3.3 %) FKBP10, one (0.8 %) in SERPINH1, and one (0.8 %) in TMEM38B. Ninety-one distinct variants were identified, of which 26 were novel. Of the 107 variants identified in COL1A1 and COL1A2, 24.5 % cause mild OI, while the remaining 75.5 % cause moderate, severe, or lethal OI, of which 49.3 % are glycine to serine substitutions. A single variant in FKBP10 (c.179A>C; p.Gln60Pro) was found in three unrelated and non-consanguineous participants living in the same geographic area in Northeast Brazil, suggesting a possible founder effect.

CONCLUSION

Consistent with the literature, 88.4 % of the subjects had a variant in the COL1A1 and COL1A2 genes, with 10 % inherited in an autosomal recessive manner. Notably, one variant in FKBP10 with a potential founder effect requires further investigation. Data from this large cohort improves our understanding of genotype-phenotype correlations for OI in Brazil.

Burden of phenylketonuria in Latin American patients: a systematic review and meta-analysis of observational studies

Background

Phenylketonuria (PKU) is an inborn error of metabolism caused by a deficiency of the enzyme phenylalanine hydroxylase. If untreated, the complications of PKU lead to significant neucognitive and neuropsychiatric impairments, placing a burden on both the individual’s quality of life and on the healthcare system. We conducted a systematic literature review to characterize the impact of PKU on affected individuals and on healthcare resources in Latin American (LATAM) countries.

Methods

Searches of the global medical literature as well as regional and local medical literature up to September 2021. Observational studies on patients with PKU from any LATAM country. Pairs of reviewers independently screened eligible articles, extracted data from included studies, and assessed their risk of bias.

Results

79 unique studies (47 cross-sectional studies, 18 case series, 12 case reports, and two cohort studies) with a total of 4090 patients were eligible. Of these studies, 20 had data available evaluating early-diagnosed PKU patients for meta-analysis of burden outcomes. Intellectual disability in the pooled studies was 18% [95% Confidence Interval (CI) 0.04–0.38; I² = 83.7%, p = 0.0133; two studies; n = 114]. Motor delay was 15% [95% CI 0.04–0.30; I² = 74.5%, p = 0.0083; four studies; n = 132]. Speech deficit was 35% [95% CI 0.08–0.68; I² = 93.9%, p < 0.0001; five studies; n = 162].

Conclusions

There is currently evidence of high clinical burden in PKU patients in LATAM countries. Recognition that there are many unmet neuropsychological needs and socioeconomic challenges faced in the LATAM countries is the first step in planning cost-effective interventions.

Supplementary Information

The online version contains supplementary material available at 10.1186/s13023-022-02450-2.

XAF1 as a modifier of p53 function and cancer susceptibility

Cancer risk is highly variable in carriers of the common TP53-R337H founder allele, possibly due to the influence of modifier genes. Whole-genome sequencing identified a variant in the tumor suppressor XAF1 (E134*/Glu134Ter/rs146752602) in a subset of R337H carriers. Haplotype-defining variants were verified in 203 patients with cancer, 582 relatives, and 42,438 newborns. The compound mutant haplotype was enriched in patients with cancer, conferring risk for sarcoma (P = 0.003) and subsequent malignancies (P = 0.006). Functional analyses demonstrated that wild-type XAF1 enhances transactivation of wild-type and hypomorphic TP53 variants, whereas XAF1-E134* is markedly attenuated in this activity. We propose that cosegregation of XAF1-E134* and TP53-R337H mutations leads to a more aggressive cancer phenotype than TP53-R337H alone, with implications for genetic counseling and clinical management of hypomorphic TP53 mutant carriers.

Comprehensive germline mutation analysis and clinical profile in a large cohort of Brazilian xeroderma pigmentosum patients

BACKGROUND

Xeroderma pigmentosum (XP) patients present a high risk of developing skin cancer and other complications at an early age. This disease is characterized by mutations in the genes related to the DNA repair system.

OBJECTIVES

To describe the clinical and molecular findings in a cohort of 32 Brazilian individuals who received a clinical diagnosis of XP.

METHODS

Twenty-seven families were screened for germline variants in eight XP-related genes.

RESULTS

All patients (N = 32) were diagnosed with bi-allelic germline pathogenic or potentially pathogenic variants, including nine variants previously undescribed. The c.2251-1G>C XPC pathogenic variant, reported as the founder mutation in Comorian and Pakistani patients, was observed in 15 cases in homozygous or compound heterozygous. Seven homozygous patients for POLH/XPV variants developed their symptoms by an average age of 7.7 years. ERCC2/XPD, DDB2/XPE and ERCC5/XPG variants were found in a few patients. Aside from melanoma and non-melanoma skin tumours, a set of patients developed skin sebaceous carcinoma, leiomyosarcoma, angiosarcoma, mucoepidermoid carcinoma, gastric adenocarcinoma and serous ovarian carcinoma.

CONCLUSIONS

We reported a high frequency of XPC variants in 32 XP Brazilian patients. Nine new variants in XP-related genes, unexpected non-skin cancer lesions and an anticipation of the clinical manifestation in POLH/XPV cases were also described.

Clonal chromosomal alterations in fibroadenomas of the breast

A cytogenetic study on short-term cell cultures from 10 fibroadenomas of the breast is reported. Clonal chromosomal alterations were observed in all cases analyzed, involving preferentially chromosomes X, 12, 14, 20, and 22. Normal karyotypes were found in 34.9% of the cells. The present findings are discussed together with the reports on fibroadenomas and other benign lesions of the breast described in the literature. Although no specific chromosome abnormality to date can be attributed to a particular type of benign breast pathology, some recurrent alterations are starting to emerge and may characterize these benign breast lesions, differentiating them from their malignant counterparts.

Noval mutation (Y184C) in exon 4 of the beta-sarcoglycan gene identified in a Portuguese patient. Mutations in brief no. 177. Online

We report a novel beta-sarcoglycan gene mutation identified in a 21-year-old Portuguese male with a progressive myopathy of intermediate severity, who had been misdiagnosed as Becker Muscular Dystrophy (BMD) based on clinical observations and muscle immunocytochemical anaylsis with dystrophin antibodies only. Since no detectable deletions or duplications were found in the dystrophin gene, we screened for mutations in the sarcoglycan genes by PCR-SSCP. The patient's sample showed a band of increased mobility in exon 4 of the beta-sarcoglycan gene which, upon sequencing, was found to represent a homozygous A-->G transversion at nucleotide 551, resulting in a tyrosine to cysteine substitution at position 184 (Y184C). Carrier status was ascertained in both parents and a sister. These aberrant conformers were not detected in 85 unrelated control individuals screened by PCR-SSCP analysis. All seven beta-sarcoglycan mutations reported to date are associated with a severe phenotype and occur in exons 3 and 4, which correspond to the immediate extracellular domain of the protein. This region contains five conserved cysteine residues. In our patient, the presence of an extra cysteine residue could interefere with intra- and/or inter-molecular disulphide bond formation. The intermediate phenotype could perhaps result from the assembly of both normal and abnormal complexes, depending on the formation of the disulphide bonds.

Clonal karyotypic abnormalities in gynecomastia

Gynecomastia is a benign condition that frequently occurs in the male breast gland; however, the cytogenetic data on this entity are very limited. To our knowledge, three cases have been reported in the literature, and the only one with an abnormal karyotype had a concomitant breast carcinoma. In this study we report clonal chromosomal alterations in a gynecomastia sample without any signs of adjacent malignant tissue. The nonrandom abnormalities observed were a deletion of 12p, monosomies of chromosomes 9, 17, 19, and 20, and the presence of a marker chromosome. Most of these alterations have been previously described in the literature in other breast lesions, including benign and malignant (male and female) tumors, indicating their recurrence and nonrandomness in abnormal processes of the mammary gland.

Say syndrome: report of a familial case

We describe a new case of Say syndrome. This syndrome is an autosomal dominant condition characterized by cleft palate, short stature of prenatal onset, large protruding ears and microcephaly, delayed bone age, and renal anomalies. The first report was in 1975 by Say et al. in three generations of a family. Three additional reports of isolated cases were published. Our propositus is a 12-month-old boy with the cardinal signs of the syndrome whose mother has only microcephaly. To our knowledge this is the second familial report with evidence of highly variable expressivity. The occurrence of renal anomalies in a son of a normal sister of his mother suggests incomplete penetrance.

Cytogenetic analysis in human bone marrow transplantation

Bone marrow transplantation (BMT) is a therapeutic process used to treat a variety of hematologic diseases. After BMT, the documentation of engrafting with the use of genetic markers is obligatory. C-band polymorphism is an excellent genetic marker because it occurs with high frequency in all populations studied and shows a high stability in vitro and in vivo. We studied a total of 36 patients: 15 with myeloid leukemia and 21 with severe aplastic anemia (SAA), submitted to BMT. The majority of the patients with chronic granulocyte leukemia (CGL; 10/15, 67%) and with SAA (17/21, 81%) showed a frequency of host cells around 15% (CGL) and 8% (SAA) in the first period analyzed (day +30 post-BMT); with a decrease in the others (+90, +180 to CGL and SAA and +365 only to CGL). In our study, the persistence of host cells in these proportions did not imply an unfavorable prognosis. On the contrary, some patients with myeloid leukemia (5/15 33%) and SAA (4/21, 19%) showed high proportions of host cells in one or more periods analyzed. If compared to the first group, these patients had, in general, a poor clinical evolution, with rejections, relapses, and deaths in greater numbers. These results show the important contribution of cytogenetic analysis in the follow-up of patients submitted to BMT.

Trisomy 4 in acute nonlymphocytic leukemia: the first Brazilian case

We report the first South American case of acute nonlymphocytic leukemia, French-American-British (FAB) subtype M1, [1] with trisomy 4 as the sole chromosome abnormality. The patient denied exposure to toxic or carcinogenic substances.

High effectiveness of aerosolized chick embryo fibroblast measles vaccine in seven-month-old and older infants

Neither the presence of hypertonic sugar nor the absence of 1% human albumin in the aerosolized chick embryo fibroblast (CEF) measles vaccine was previously found to be responsible for its inadequacy in infants with titers of maternal plaque-neutralizing (PN) antibody at which human diploid cell measles vaccine was immunogenic. Eight weeks after administration of CEF measles vaccine containing 1% human albumin, antibody had developed in all 10 infants 7-10 months old and all 11 children 12-35 months old but in only 26% of 23 infants 3-5 months old and 67% of 9 infants 6 months of age. Failure of antibody development was associated with prevaccination PN antibody titers of greater than or equal to 1:50 (with one exception at a titer of 1:25). The PN antibody response to CEF vaccine (diluted 1:10, approximately 10(5) pfu/ml) in infants under seven months of age (geometric mean titer [GMT], 1:421) was significantly lower (P less than .005) than in older infants (GMT, 1:1,564). At a 1:1,000 dilution of vaccine, only 50% of 10 infants 13-25 months old, 20% of 15 infants 7-10 months old, and none of 8 infants 6 months old developed antibody.