Variant-specific pathophysiological mechanisms of AFF3 differently influence transcriptome profiles.

BACKGROUND: We previously described the KINSSHIP syndrome, an autosomal dominant disorder associated with intellectual disability (ID), mesomelic dysplasia and horseshoe kidney, caused by de novo variants in the degron of AFF3. Mouse knock-ins and overexpression in zebrafish provided evidence for a dominant-negative mode of action, wherein an increased level of AFF3 resulted in pathological effects. METHODS: Evolutionary constraints suggest that other modes-of-inheritance could be at play. We challenged this hypothesis by screening ID cohorts for individuals with predicted-to-be damaging variants in AFF3. We used both animal and cellular models to assess the deleteriousness of the identified variants. RESULTS: We identified an individual with a KINSSHIP-like phenotype carrying a de novo partial duplication of AFF3 further strengthening the hypothesis that an increased level of AFF3 is pathological. We also detected seventeen individuals displaying a milder syndrome with either heterozygous Loss-of-Function (LoF) or biallelic missense variants in AFF3. Consistent with semi-dominance, we discovered three patients with homozygous LoF and one compound heterozygote for a LoF and a missense variant, who presented more severe phenotypes than their heterozygous parents. Matching zebrafish knockdowns exhibit neurological defects that could be rescued by expressing human AFF3 mRNA, confirming their association with the ablation of aff3. Conversely, some of the human AFF3 mRNAs carrying missense variants identified in affected individuals did not rescue these phenotypes. Overexpression of mutated AFF3 mRNAs in zebrafish embryos produced a significant increase of abnormal larvae compared to wild-type overexpression further demonstrating deleteriousness. To further assess the effect of AFF3 variation, we profiled the transcriptome of fibroblasts from affected individuals and engineered isogenic cells harboring + / + , KINSSHIP/KINSSHIP, LoF/ + , LoF/LoF or KINSSHIP/LoF AFF3 genotypes. The expression of more than a third of the AFF3 bound loci is modified in either the KINSSHIP/KINSSHIP or the LoF/LoF lines. While the same pathways are affected, only about one third of the differentially expressed genes are common to the homozygote datasets, indicating that AFF3 LoF and KINSSHIP variants largely modulate transcriptomes differently, e.g. the DNA repair pathway displayed opposite modulation. CONCLUSIONS: Our results and the high pleiotropy shown by variation at this locus suggest that minute changes in AFF3 function are deleterious.

Variant-specific pathophysiological mechanisms of AFF3 differently influence transcriptome profiles.

Background: We previously described the KINSSHIP syndrome, an autosomal dominant disorder associated with intellectual disability (ID), mesomelic dysplasia and horseshoe kidney,caused by de novo variants in the degron of AFF3. Mouse knock-ins and overexpression in zebrafish provided evidence for a dominant-negative (DN) mode-of-action, wherein an increased level of AFF3 resulted in pathological effects. Methods: Evolutionary constraints suggest that other mode-of-inheritance could be at play. We challenged this hypothesis by screening ID cohorts for individuals with predicted-to-be deleterious variants in AFF3. We used both animal and cellular models to assess the deleteriousness of the identified variants. Results: We identified an individual with a KINSSHIP-like phenotype carrying a de novo partial duplication of AFF3 further strengthening the hypothesis that an increased level of AFF3 is pathological. We also detected seventeen individuals displaying a milder syndrome with either heterozygous LoF or biallelic missense variants in AFF3. Consistent with semi-dominance, we discovered three patients with homozygous LoF and one compound heterozygote for a LoF and a missense variant, who presented more severe phenotypes than their heterozygous parents. Matching zebrafish knockdowns exhibit neurological defects that could be rescued by expressing human AFF3 mRNA, confirming their association with the ablation of aff3. Conversely, some of the human AFF3 mRNAs carrying missense variants identified in affected individuals did not complement. Overexpression of mutated AFF3 mRNAs in zebrafish embryos produced a significant increase of abnormal larvae compared to wild-type overexpression further demonstrating deleteriousness. To further assess the effect of AFF3 variation, we profiled the transcriptome of fibroblasts from affected individuals and engineered isogenic cells harboring +/+, DN/DN, LoF/+, LoF/LoF or DN/LoF AFF3 genotypes. The expression of more than a third of the AFF3 bound loci is modified in either the DN/DN or the LoF/LoF lines. While the same pathways are affected, only about one-third of the differentially expressed genes are common to these homozygote datasets, indicating that AFF3 LoF and DN variants largely modulate transcriptomes differently, e.g. the DNA repair pathway displayed opposite modulation. Conclusions: Our results and the high pleiotropy shown by variation at this locus suggest that minute changes in AFF3 function are deleterious.

Tumores cardiacos fetales: importancia del diagnóstico prenatal y repercusiones perinatales / Fetal cardiac tumors. Case series: Importance of prenatal diagnosis and perinatal impact

Resumen ANTECEDENTES Los tumores cardiacos fetales son hallazgos esporádicos en el ultrasonido fetal con una incidencia de 1 caso por cada 10,000 nacidos vivos. Los rabdomiomas son los tumores cardiacos más comunes en la vida intrauterina (60-86%) seguidos por los fibromas y teratomas. Casi siempre tienen regresión espontánea, pueden ocasionar alteraciones hemodinámicas e incrementar la morbilidad y mortalidad perinatal; además de su importante asociación con el complejo de la esclerosis tuberosa, enfermedad genésica que cursa con epilepsia y déficit cognitivo. OBJETIVO Reportar la primera serie mexicana de casos de detección prenatal de rabdomiomas. MATERIALES Y MÉTODOS Estudio retrospectivo consistente en la revisión de los expedientes de todos los fetos con diagnóstico prenatal de tumores cardiacos registrados de enero de 2007 a diciembre de 2017 en el Hospital Ángeles Lomas. A todas las pacientes se les realizó ultrasonido de segundo nivel y ecocardiografía avanzada prenatal y postnatal. RESULTADOS Se estudiaron siete casos, la mayoría con tumoraciones únicas. En un caso hubo alteraciones hemodinámicas durante el periodo fetal que le ocasionaron la muerte. En dos casos se confirmó esclerosis tuberosa. CONCLUSIONES Se trata de la primera serie de casos mexicanos de tumores cardiacos fetales. Los hallazgos fueron similares a los reportados en la bibliografía mundial, excepto que se encontraron más casos de tumores únicos que de múltiples. El tamaño del tumor, el número y la localización pueden predecir el pronóstico perinatal y, en especial, la posibilidad de esclerosis tuberosa.

Abstract BACKGROUND Fetal cardiac tumors are sporadic findings in fetal ultrasound with an incidence of 1 case per 10,000 live births. Rhabdomyomas are the most common cardiac tumors in intrauterine life (60-86%) followed by fibroids and teratomas. They almost always have spontaneous regression, can cause hemodynamic alterations and increase perinatal morbidity and mortality; in addition to its important association with the tuberous sclerosis complex, a genetic disease that presents with epilepsy and cognitive deficit. OBJECTIVE To report the first Mexican series of cases of prenatal detection of rhabdomyomas. MATERIALS AND METHODS Retrospective study consisting of the review of the records of all fetuses with prenatal diagnosis of cardiac tumors registered from January 2007 to December 2017 at the Ángeles Lomas Hospital. All patients underwent second-level ultrasound and advanced prenatal and postnatal echocardiography. RESULTS Seven cases were studied, most of them with single tumors. In one case there were hemodynamic alterations during the fetal period that caused his death. In two cases, tuberous sclerosis was confirmed. CONCLUSIONS This is the first series of Mexican cases of fetal cardiac tumors. The findings were similar to those reported in the world literature, except that more cases of single tumors were found than multiple tumors. The size of the tumor, the number and the location can predict the perinatal prognosis and, especially, the possibility of tuberous sclerosis.

Partial trisomy 9: prenatal diagnosis and recurrence within same family.

Trisomy 9 can be suspected and confirmed in the prenatal period since the 11-13.6 weeks of screening. In cases of partial trisomy 9, the diagnosis is important especially to counseling the couple due to the increased likelihood of recurrence in subsequent pregnancies.