Carrier screening in the Mexican Jewish community using a pan-ethnic expanded carrier screening NGS panel

PURPOSE

The Mexican Jewish community (MJC) is a previously uncharacterized, genetically isolated group composed of Ashkenazi and Sephardi-Mizrahi Jews who migrated in the early 1900s. We aimed to determine the heterozygote frequency of disease-causing variants in 302 genes in this population.

METHODS

We conducted a cross-sectional study of the MJC involving individuals representing Ashkenazi Jews, Sephardi-Mizrahi Jews, or mixed-ancestry Jews. We offered saliva-based preconception pan-ethnic expanded carrier screening, which examined 302 genes. We analyzed heterozygote frequencies of pathogenic/likely pathogenic variants and compared them with those in the Genome Aggregation Database (gnomAD).

RESULTS

We recruited 208 participants. The carrier screening results showed that 72.1% were heterozygous for at least 1 severe disease-causing variant in 1 of the genes analyzed. The most common genes with severe disease-causing variants were CFTR (16.8% of participants), MEFV (11.5%), WNT10A (6.7%), and GBA (6.7%). The allele frequencies were compared with those in the gnomAD; 85% of variant frequencies were statistically different from those found in gnomAD (P <.05). Finally, 6% of couples were at risk of having a child with a severe disorder.

CONCLUSION

The heterozygote frequency of at least 1 severe disease-causing variant in the MJC was 72.1%. The use of carrier screening in the MJC and other understudied populations could help parents make more informed decisions.

Causal analysis of fetal death in high-risk pregnancies

OBJECTIVES

To determine the causes of fetal death among the stillbirths using two classification systems from 22 weeks of gestation in a period of three years in high-risk pregnancies. This is a retrospective observational study.

METHODS

The National Institute of Perinatal Health in Mexico City is a Level 3 care referral center attending high-risk pregnancies from throughout the country. The population consisted of patients with fetal death during a three-year period. Between January 2016 and December 2018, all stillbirths were examined in the Pathology Department by a pathologist and a medical geneticist. Stillbirth was defined as a fetal death occurring after 22 weeks of gestation.

RESULTS

Main outcome measures: Causal analysis of fetal death using the International Statistical Classification of Disease and Related Health Problems-Perinatal Mortality (ICD-PM) and initial causes of fetal death (INCODE) classification systems. A total of 297 stillborn neonates were studied. The distribution of gestational age in antepartum stillbirths (55.2%) showed a bimodal curve, 36% occurred between 24 and 27 weeks and 32% between 32 and 36 weeks. In comparison, the majority (86%) of intrapartum deaths (44.8%) were less than 28 weeks of gestation. Of the 273 women enrolled, 93 (34%) consented to a complete fetal autopsy. The INCODE system showed a present cause in 42%, a possible cause in 54% and a probable cause in 93% of patients.

CONCLUSIONS

The principal causes of antepartum death were fetal abnormalities and pathologic placental conditions and the principal causes of intrapartum death were complications of pregnancy which caused a premature labor and infections.

Heterogeneous Diagnoses Underlying Radial Ray Anomalies

OBJECTIVE

To review perinatal Radial Ray Anomaly (RRA) cases born at the National Institute of Perinatology, Mexico, and to reveal the heterogeneous diagnoses of these patients.

METHODS

All patients with RRA over a 18 mo period were included; 4/15 were detected prenatally and 11/15 postnatally. Karyotype was performed for all patients with bilateral RRA; and chromosomal breakage analysis, when the karyotype was normal.

RESULTS

Fifteen RRA patients were identified: one with trisomy 18, three with an isolated defect, six with monogenic disease, four with a genetic association and one with diabetic embryopathy. Five were stillborn and two died during the early neonatal period; all of whom presented with multiple defects. Three of the live born patients and one stillborn with multiple defects had Fanconi anemia. RRAs carry a high perinatal mortality rate (47%) when they occur in association with other defects.

CONCLUSIONS

The assessment of these patients needs to involve the combined use of ultrasound, clinical, genetic, cytogenetic and molecular testing. The present results indicate that the chromosome breakage test should always be performed to rule out Fanconi anemia in this group.

Prenatal diagnosis of trisomy 21 without the Down syndrome phenotype

OBJECTIVE

To report a patient with the prenatal diagnosis of trisomy 21 without the clinical Down syndrome (DS) phenotype secondary to the absence of the Down syndrome chromosomal region (DSCR) in a derivative chromosome 21.

CASE REPORT AND METHODS

A newborn patient with prenatal diagnosis of duodenal atresia. Cytogenetic studies revealed a regular trisomy 21. At birth, she did not present the clinical features of DS. FISH analysis was performed in the patient with the LSI spectrum probe for the DSCR and in the mother with FISH multicolor analysis using painting probes for chromosomes 20 and 21.

RESULTS

FISH analysis in the patient showed two hybridization signals suggesting that the third chromosome 21 did not have the DSCR region explaining the absence of the DS phenotype. FISH multicolor analysis in the mother showed three hybridization signals for chromosomes 20 and 21, concluding a maternal karyotype, 46,XX,t(20;21)(p11.2;q22.1).

CONCLUSIONS

The patient was found to have a derivative chromosome 21 secondary to a nondisjunction error in meiosis II without the DS critical region and the phenotype was mostly secondary to the combination of the two partial trisomies.

Use of plasma exchange and heparin during cardiopulmonary bypass for a patient with heparin induced thrombocytopenia: a case report

Patients with documented history of heparin-induced thrombocytopenia (HIT) pose a difficult problem during surgery using cardiopulmonary bypass (CPB). Several alternatives to heparin exist, but these products either are not approved for use in the United States or have more side effects than heparin. We report on a patient with documented heparin-induced antibody and left main coronary artery disease who underwent uneventful coronary artery bypass surgery and recovery by using preoperative plasmaphresis and limited use of porcine intestinal heparin during CPB.

PCR-PRINS-FISH analysis of structurally abnormal sex chromosomes in eight patients with Turner phenotype

According to cytogenetic analysis, about 50% of Turner individuals are 45,X. The remaining cases have a structurally abnormal X chromosome or are mosaics with a second cell line containing a normal or abnormal sex chromosome. In these mosaics, approximately 20% have a sex marker chromosome whose identity cannot usually be determined by classical cytogenetic methods, requiring the use of molecular techniques. Polymerase chain reaction (PCR), primed in situ labeling (PRINS), and fluorescence in situ hybridization (FISH) analyses were performed in 8 patients with Turner syndrome and 45,X mosaic karyotypes to determine the origin and structure of the marker chromosome in the second cell line. Our data showed that markers were Y-derived in 2 patients and X-derived in the remaining 6 patients. We were also able to determine the breakpoints in the two Y chromosomes. The use of cytogenetic and molecular techniques allowed us to establish unequivocally the origin, X or Y, of the marker chromosomes in the 8 patients with Turner phenotype. This study illustrates the power of resolution and utility of combined cytogenetic and molecular approaches in some clinical cases.

Severe hemorrhagic complication due to acquired factor V inhibitor after single exposure to bovine thrombin product

Hemorrhagic complications have been reported after repeated exposures to bovine thrombin products due to development of factor V inhibitors. Our patient underwent emergency repair of acute aortic dissection and coronary artery bypass grafting. The patient developed leg wound infection at the saphenous vein harvest site, which was debrided and left open. Attempt to reclose the leg wound 1 month later was complicated by a life-threatening hemorrhage with markedly elevated activated partial thromboplastin time. There was no evidence of infection or disseminated intravascular coagulation, and further study identified low factor V level with positive factor V inhibitor. Treatment with plasmapheresis and steroid successfully reversed the coagulopathy. Detailed case review failed to reveal exposure to any thrombin products other than the one used for the aortic dissection repair. This case was unusual because only a single exposure to this product resulted in severe hemorrhagic complication 1 month after surgery.

[Eating disorders]

At the present time, research into Eating Disorders is being carried out in very different areas: clinical and diagnostic, epidemiological, comorbidity, aetiopathogeny, treatment and forms of care. This paper reviews this type of pathology, and aims to update the most important data in the different fields. The epidemiological studies of recent decades would indicate a considerable increase in the rates of incidence and prevalence of both Nervous Anorexia and Nervous Bulimia. On the other hand, there is increasing confirmation of an early appearance of these disorders. Similarly, the discovery of certain physiopathological appetite markers and/or regulators opens a new path for understanding this phenomenon. Research into these problems has reached a certain consensus in aspects such as: a multidimensional consideration of the ethiopathogeny, increasingly purified diagnostic criteria, care and therapeutic procedures and resources to be used in treatment.

Frequency of Y chromosomal material in Mexican patients with Ullrich-Turner syndrome

Cytogenetic studies have shown that 40-60% of patients with Ullrich-Turner syndrome (UTS) are 45,X, whereas the rest have structural aberrations of the X chromosome or mosaicism with a second cell line containing a structurally normal or abnormal X or Y chromosome. However, molecular analysis has demonstrated a higher proportion of mosaicism, and studies in different populations have shown an extremely variable frequency of Y mosaicism of 0-61%. We used Southern blot analysis and polymerase chain reaction (PCR) to detect the presence of Ycen, ZFY, SRY, and Yqh in 50 Mexican patients with UTS and different karyotypes to determine the origin of marker chromosomes and the presence of Y sequences. Our results indicated the origin of the marker chromosome in 1 patient and detected the presence of Y sequences in 4 45,X patients. Taken together, we found a 12% incidence of Y sequences in individuals with UTS. The amount of Y-derived material was variable, making the correlation between phenotype and molecular data difficult. Only 1 patient had a gonadoblastoma. We discuss the presence of Y chromosomes or Y sequences in patients with UTS and compare our frequency with that previously reported.

Triphalangeal thumb and brachyectrodactyly syndrome: an uncommon entity with evidence of geographic distribution

A new Mexican family with the triphalangeal thumb-brachyectrodactyly syndrome is described. The proposita, a 17-year-old female, showed the classic malformation pattern: triphalangeal thumb, brachysyndactyly in the hands and ectrodactyly in the feet. Several members of the family had similar malformations, and others presented minor manifestations of the disease (brachydactyly and nail dysplasia). This is the fourth familial case reported in the literature with the triphalangeal thumb and brachyectrodactyly complex and the third of Mexican origin, reflecting a geographical predominance in the occurrence of this uncommon pathology.

Heparin bonding of bypass circuits reduces cytokine release during cardiopulmonary bypass

BACKGROUND

Heparin bonding of the cardiopulmonary bypass (CPB) pump circuit decreases complement activation and fibrinolysis. It is not known whether inflammatory cytokines produced during CPB can also be modulated by the more biocompatible heparin-coated circuit.

METHODS

This initial study evaluated the impact of heparin-bonded CPB circuits on production of the cytokines interleukin-1 (IL-1), tumor necrosis factor-alpha (TNF-a), IL-6, and IL-8 in adults undergoing complex cardiac operations with prolonged CPB. Twenty patients had blood samples drawn immediately before and at hourly intervals after the start of CPB using either a conventional oxygenator and circuit (n = 14) or a covalently bonded heparin oxygenator and circuit (n = 6). Levels of IL-1, TNF-a, IL-6, and IL-8 were measured in all serum samples using a "sandwich" enzyme-linked immunosorbent assay.

RESULTS

The levels of IL-6 and IL-8 increased in a time-dependent fashion in both groups, but the response was significantly less over time in the heparin-bonded group (p < 0.05) for both IL-6 and IL-8. Levels of IL-1 and TNF-a were not significantly elevated with lengthening bypass interval in either group.

CONCLUSIONS

These data indicate that the use of heparin-coated bypass pump circuits results in lower serum levels of the inflammatory cytokines IL-6 and IL-8 than standard circuits. Biocompatible materials that decrease the inflammatory response to CPB may ultimately reduce the morbidity associated with cardiac operations.

Chromosomal mapping and nucleotide sequence of a human DNA autonomously replicating sequence

A 1.1-kb human DNA fragment (ARSH1) capable of functioning as a putative origin of replication in yeast cells has been characterized both by in situ hybridization to human metaphase chromosomes and by DNA sequencing. Our hybridization studies show a preferential localization of ARSH1 in chromosome regions 1p34-36 and 2q34-37. DNA sequence analysis indicates that in addition to the consensus sequence required for ARS function in yeast cells, nuclear matrix-associated DNA motifs are also present in the 1.1-kb fragment. These results suggest that ARSH1 sequences may serve as points of anchorage to the nuclear matrix for chromosomes 1 and 2.