Alport syndrome and pregnancy: a case series and literature review

Reassuring pregnancy outcomes in women with mild COL4A3-5-related disease (Alport syndrome) and genetic type of disease can aid personalized counseling

Individualized pre-pregnancy counseling and antenatal care for women with chronic kidney disease (CKD) require disease-specific data. Here, we investigated pregnancy outcomes and long-term kidney function in women with COL4A3-5 related disease (Alport Syndrome, (AS)) in a large multicenter cohort. The ALPART-network (mAternaL and fetal PregnAncy outcomes of women with AlpoRT syndrome), an international collaboration of 17 centers, retrospectively investigated COL4A3-5 related disease pregnancies after the 20th week. Outcomes were stratified per inheritance pattern (X-Linked AS (XLAS)), Autosomal Dominant AS (ADAS), or Autosomal Recessive AS (ARAS)). The influence of pregnancy on estimated glomerular filtration rate (eGFR)-slope was assessed in 192 pregnancies encompassing 116 women (121 with XLAS, 47 with ADAS, and 12 with ARAS). Median eGFR pre-pregnancy was over 90ml/min/1.73m2. Neonatal outcomes were favorable: 100% live births, median gestational age 39.0 weeks and mean birth weight 3135 grams. Gestational hypertension occurred during 23% of pregnancies (reference: 'general' CKD G1-G2 pregnancies incidence is 4-20%) and preeclampsia in 20%. The mean eGFR declined after pregnancy but remained within normal range (over 90ml/min/1.73m2). Pregnancy did not significantly affect eGFR-slope (pre-pregnancy β=-1.030, post-pregnancy β=-1.349). ARAS-pregnancies demonstrated less favorable outcomes (early preterm birth incidence 3/11 (27%)). ARAS was a significant independent predictor for lower birth weight and shorter duration of pregnancy, next to the classic predictors (pre-pregnancy kidney function, proteinuria, and chronic hypertension) though missing proteinuria values and the small ARAS-sample hindered analysis. This is the largest study to date on AS and pregnancy with reassuring results for mild AS, though inheritance patterns could be considered in counseling next to classic risk factors. Thus, our findings support personalized reproductive care and highlight the importance of investigating kidney disease-specific pregnancy outcomes.

Genetic Diagnosis of Adult Hemodialysis Patients With Unknown Etiology

Introduction

Kidney disease of unknown etiology accounts for 1 in 10 adult end-stage renal disease (ESRD) cases worldwide. The aim of this study is to clarify the genetic background of patients with chronic kidney disease (CKD) of unknown etiology who initiated renal replacement therapy (RRT) in adulthood.

Methods

This is a multicenter cross-sectional cohort study. Of the 1164 patients who attended 4 dialysis clinics in Japan, we first selected patients who started RRT between the ages of 20 and 49 years. After excluding patients with apparent causes of CKD (e.g., diabetic nephropathy, polycystic kidney disease (PKD) with family history, patients who underwent renal biopsy), 90 patients with CKD of unknown cause were included. The 298 genes associated with CKD were analyzed using capture-based targeted next-generation sequencing.

Results

Of the 90 patients, 10 (11.1%) had pathogenic variants in CKD-causing genes and 17 (18.9%) had variant of unknown significance (VUS). Three patients had PKD1 pathogenic variants, and 1 patient had PKD1 and COL4A4 pathogenic variants. In addition, 2 patients were diagnosed with atypical hemolytic uremic syndrome (aHUS) due to C3 or CFHR5. One patient each was diagnosed with Alport syndrome due to COL4A4 and COL4A3 variants, nephronophthisis due to NPHP1 variants, Fabry disease due to GLA variants, and autosomal-dominant tubulointerstitial kidney disease due to UMOD variants. Genetic diagnoses were not concordant with clinical diagnoses, except for patients with PKD1 variant.

Conclusion

This largest study on genetic analysis in hemodialysis-dependent adults revealed the presence of undiagnosed inherited kidney diseases.

Reproductive Carrier Screening Results With Maternal Health Implications During Pregnancy

OBJECTIVE

To identify conditions on a reproductive carrier screening panel with the potential for carrier manifestations during pregnancy and review the implications for obstetric care.

METHODS

This was a retrospective cross-sectional study of consecutive samples from female patients aged 18-55 years submitted to a commercial laboratory for a 274-gene carrier screening panel (January 2020 to September 2022). A literature review was performed to identify genes on the panel with potential for pregnancy complications in carriers. Carrier expression and published recommendations for clinical management were reviewed.

RESULTS

We identified 12 genes with potential for carrier manifestations during pregnancy based on reports in the literature: nine with manifestations irrespective of the fetal genetic status ( ABCB11 , COL4A3 , COL4A4 , COL4A5 , DMD , F9 , F11 , GLA , and OTC ) and three ( CPT1A , CYP19A1 , and HADHA ) with manifestations only if the fetus is affected by the condition. Manifestations included cardiomyopathy, hemorrhage, gestational hypertensive disorders, cholestasis of pregnancy, acute fatty liver, hyperammonemic crisis, and maternal virilization. Published recommendations for carrier management were identified for 11 of the 12 genes. Of 91,637 tests performed during the study period, a pathogenic or likely pathogenic variant was identified in 2,139 (2.3%), giving a carrier frequency for any of the 12 genes of 1 in 43 (95% CI 1/41-45) 1,826 (2.0%) of the study population were identified as carriers for one of the nine genes with the potential for carrier manifestations irrespective of an affected or unaffected fetus.

CONCLUSION

Approximately 1 in 40 female patients were identified as carriers for a condition with potential for maternal manifestations in pregnancy, including some serious or even life-threatening complications. Obstetric care professionals should be aware of the possibility of pregnancy complications among carriers and the available recommendations for management.

FUNDING SOURCE

This study was funded by Natera, Inc.

Maternal health and pregnancy outcomes in autosomal dominant tubulointerstitial kidney disease

Introduction

Autosomal dominant tubulointerstitial kidney disease (ADTKD) is an increasingly recognized cause of chronic kidney disease. ADTKD pregnancy outcomes have not previously been described.

Methods

A cross-sectional survey was sent to women from ADTKD families.

Results

Information was obtained from 85 afffected women (164 term pregnancies) and 23 controls (50 pregnancies). Only 16.5% of genetically affected women knew they had ADTKD during pregnancy. Eighteen percent of ADTKD mothers had hypertension during pregnancy versus 12% in controls (p  =  0.54) and >40% in comparative studies of chronic kidney disease in pregnancy. Eleven percent of births of ADTKD mothers were <37 weeks versus 0 in controls (p < 0.0001). Cesarean section occurred in 19% of pregnancies in affected women versus 38% of unaffected individuals (p  =  0.06). Only 12% of babies required a neonatal intensive care unit stay.

Conclusions

ADTKD pregnancies had lower rates of hypertension during pregnancy versus other forms of chronic kidney disease, which may have contributed to good maternal and fetal outcomes.

Good maternal and fetal outcomes of three consecutive pregnancies in a Mediterranean woman with Alport syndrome: a case report

BACKGROUND

Alport syndrome is a rare inherited disorder affecting the glomerular basement membrane, manifested by hematuria and proteinuria that is commonly associated with ocular and hearing defects. There is limited information about the maternal and fetal outcomes of Alport syndrome in pregnancy.

CASE PRESENTATION

We describe a smooth course of pregnancy, a good maternal outcome, and a good fetal outcome in three consecutive pregnancies for a 35-year-old Mediterranean woman with Alport syndrome over a 10-year duration. Although there was a nephrotic range of progressive proteinuria in all her pregnancies, there was a prompt drop in proteinuria within 2 weeks of her deliveries. She has constantly shown a normal serum creatinine level and a normal serum protein level in all her pregnancies. Apart from a single episode of asymptomatic hypertension in her second pregnancy at 34 weeks of gestation that returned to a normal range immediately after delivery, she was normotensive antenatally and postnatally. She gave birth by cesarean section to three healthy newborns.

CONCLUSIONS

A normal prepregnancy creatinine level and a mild range of proteinuria in a patient with normotension, who is not on any medication, are associated with good maternal and fetal outcomes. Furthermore, successful pregnancy that is followed by a normal renal function test might suggest a favorable outcome for any future pregnancy.

What the Adult Nephrologist Should Know About Alport Syndrome

Recent trends in the diagnosis, treatment, and classification of collagen IV-associated kidney disease are likely to result in increasing numbers of people in adult nephrology practices who have a confirmed diagnosis of Alport syndrome. These trends include the increasing use of genetic testing in the diagnostic evaluation of people with hematuria, focal segmental glomerulosclerosis, and chronic kidney disease of unknown etiology; early treatment with inhibitors of the renin-angiotensin-aldosterone system to delay kidney failure; and application of an expanded definition of Alport syndrome based on genotype rather than phenotype. This commentary discusses these trends and their implications for the adult nephrologist.

X-Linked Kidney Disorders in Women

A number of genes that cause inherited kidney disorders reside on the X chromosome. Given that males have only a single active X chromosome, these disorders clinically manifest primarily in men and boys. However, phenotypes in female carriers of X-linked kidney conditions are becoming more and more recognized. This article reviews the biology of X inactivation as well as the kidney phenotype in women and girls with a number of X-linked kidney disorders including Alport syndrome, Fabry disease, nephrogenic diabetes insipidus, X-linked hypophosphatemic rickets, Dent disease, and Lowe syndrome.

A Novel Homozygous Mutation in the COL4A4 Gene (Gly1436del) Causing Alport Syndrome Exposed by Pregnancy: A Case Report and Review of the Literature

Background

Alport syndrome results from a hereditary defect of collagen IV synthesis. This causes progressive glomerular disease, ocular abnormalities, and inner ear impairment. Case Presentation. Herein, we present a case of Alport syndrome in a 28-year-old woman caused by a novel mutation (Gly1436del) in the COL4A4 gene that was not unveiled until her first pregnancy. Within the 29^th pregnancy week, our patient presented with massive proteinuria and nephrotic syndrome. Light microscopic examination of a kidney biopsy showed typical histological features of segmental sclerosis, and electron microscopy revealed extensive podocyte alterations as well as thickness of glomerular basement membranes with splitting of the lamina densa. One and a half years after childbirth, renal function deteriorated to a preterminal stage, whereas nephrotic syndrome subsided quickly after delivery.

Conclusion

This case report highlights the awareness of atypical AS courses and emphasizes the importance of genetic testing in such cases.

Preimplantation Genetic Testing Prevented Intergenerational Transmission of X-Linked Alport Syndrome

BACKGROUND

Alport syndrome (AS) is a hereditary renal basement membrane disease that can lead to end-stage renal disease in young adults. It can be diagnosed by genetic analysis, being mostly caused by mutations in COL4A3, COL-4A4, and COL4A5. To date, there is no radical cure for this disease.

OBJECTIVES

The aim of this study was to avoid the transmission of AS within an affected family by selecting healthy embryos for uterine transfer. The embryos were identified by preimplantation genetic testing for monogenic disorders (PGT-M).

METHODS

We used next-generation sequencing (NGS) to identify mutations in the proband and his parents. The results of NGS were confirmed by Sanger sequencing. Targeted NGS combined with targeted single-nucleotide polymorphism haplotyping was used for the in vitro identification of COL4A5 mutations in human embryos to prevent their intergenerational transmission.

RESULTS

The c.349_359delGGACCTCAAGG and c.360_361insTGC mutations in COL4A5 were identified in a family affected by X-linked AS. Whole-genome sequencing by NGS with targeted haplotyping was performed on biopsied trophectoderm cells. A healthy baby was born after transfer of a single freeze-thawed blastocyst.

CONCLUSIONS

The use of targeted NGS for identifying diagnostic markers combined with targeted haplotyping is an easy and efficient PGT-M method for preventing intergenerational transmission of AS.

Multidisciplinary Management of Alport Syndrome: Current Perspectives

Alport syndrome is a multisystem disorder that universally affects the kidney and frequently involves the inner ear and the eye. Over the course of a lifetime, addressing the health care needs of a person with Alport syndrome and their family entails the services of primary providers, nephrologists, genetic counselors, audiologists, ophthalmologists, transplant physicians, kidney dieticians, and social workers as well as other healthcare professionals. This article attempts to provide context and guidance regarding the multidisciplinary care of Alport syndrome based on the natural history of the condition.

Case Report: Preimplantation Genetic Testing and Pregnancy Outcomes in Women With Alport Syndrome

Background

Alport syndrome, a monogenic kidney disease, is characterized by progressive hemorrhagic nephritis, sensorineural hearing loss, and ocular abnormalities. Mutations in COL4A5 at Xq22 accounts for 80–85% of X-linked Alport syndrome patients. Three couples were referred to our reproductive genetics clinic for prenatal or preconception counseling.

Methods

Prenatal diagnoses were performed by amplifying targeted regions of COL4A5. Targeted next-generation sequencing (NGS)-based haplotype analysis or karyomapping was performed in two patients. Pregnancy outcomes in the three patients were collected and analyzed. Published Alport syndrome cases were searched in Pubmed and Embase.

Results

Prenatal diagnoses in two cases showed one fetus harbored the same pathogenic mutation as the proband and the other was healthy. The couple with an affected fetus and the patient with a family history of Alport syndrome chose to take the preimplantation genetic testing (PGT) procedure. One unaffected embryo was transferred to the uterus, and a singleton pregnancy was achieved, respectively. Two patients presented non-nephrotic range proteinuria (<3 g/24 h) during pregnancy and the three cases all delivered at full-term. However, published Alport cases with chronic kidney disease or proteinuria during pregnancy were came with a high rate (75%) of adverse maternal and fetal outcomes.

Conclusion

The PGT procedure performed in this study was proven to be practicable and might be expanded to be applied in other monogenic diseases. Moderate or severe renal impairments in Alport syndrome were strongly associated with adverse maternal and fetal outcomes, and baseline proteinuria was a potential predictor for pregnancy outcomes of Alport syndrome as other kidney diseases.

Renal impairment in Alport syndrome pregnant woman: Case report and review of the literature

Pregnant women affected by Alport syndrome often struggle with worsening of renal function during pregnancy. We focused the attention on the optimal management of the kidney disease in these women in order to avoid maternal-fetal complications.

Autosomal Recessive Alport Syndrome Unveiled by Pregnancy

Alport syndrome is a hereditary disease affecting Type IV collagen characterized by hematuria, progressive renal failure, sensorineural hearing loss, and ocular abnormalities. Most cases are X-linked and involve the COL4A5 gene with a minority of patients having autosomal recessive mutations in the COL4A3 or COL4A4 genes encoding the α3(IV) or α4(IV) chain respectively. Here, we describe the case of a 31-year-old woman who presented during pregnancy with hematuria and proteinuria and was diagnosed with autosomal recessive Alport syndrome (ARAS) post-partum. Her biopsy was notable for findings of segmental glomerulosclerosis with some collapsing features, in addition to thin basement membranes and rare "splitting". Genetic testing identified 2 novel mutations in the COL4A4 gene: a truncating frame shift mutation c.3861delinsCTC and a missense mutation c.4708G>A (p.Glu1570Lys), both of which we assert to be pathogenic. She had normal full-term delivery without complications. This case has several unique features including the relatively mild disease phenotype and the findings of glomerular scarring with collapsing features on renal biopsy. The successful pregnancy outcome and her clinical presentation add to the growing body of evidence that ARAS can have a variable phenotype.

Successful management of twin pregnancy in a woman with advanced chronic kidney disease: A case report

RATIONALE

Twin pregnancy in women with chronic kidney disease (CKD) is very rare but poses a great risk to both mother and children. In developing countries like China, advanced CKD twin pregnancies are often terminated. Here, we report a successful case and reviewed related cases, hope to facilitate further study.

PATIENT CONCERNS

A 29-year-old woman with a twin pregnancy showed serum creatinine (Scr) 100 μmol/L (CKD2) at conception. During her 12th week, Scr reached 263 μmol/L (CKD4) with urine protein 3+ and hypertension.

DIAGNOSES

Due to her pregnancy, renal biopsy was not considered. Lab tests showed deterioration of renal function and ultrasound detections showed small kidney size.

INTERVENTIONS

The patient was given basic drug therapy to control her blood pressure and supplemental nutrition without hemodialysis.

OUTCOMES

The patient delivered 2 healthy babies weighting 0.9 and 0.7 kg by cesarean section at the 28th week, but has been under maintenance hemodialysis since then.

LESSONS

Despite low birth weight and preterm delivery, successful twin pregnancies in some patients with CKD could be realized under early multidisciplinary intervention, but this poses great risks for mothers and twins, especially for patients with advanced CKD and those on hemodialysis.

Twin pregnancy in a patient on chronic haemodialysis who already had three pregnancies

Pregnancy in women with end-stage renal disease is rare. Multiple pregnancies carry a high risk of complications even in healthy individuals. We report the case of a 36-year-old woman who had four pregnancies while she was on dialysis, including one twin pregnancy. The last pregnancy occurred while in the 14th year of hemodialysis. At 8 weeks of gestation (WG), ultrasonography diagnosed a dichorionic diamniotic twin pregnancy. The frequency of dialysis was increased from 3 to 6 times a week and each session lasted 4 h. At 22 WG, polyhydramnios was diagnosed. At 25 WG, the patient presented respiratory distress and was transferred to intensive care where continuous hemodialysis, non-invasive ventilation, antibiotic and tocolysis were initiated. Because of tocolysis failure, a cesarean section was performed and she delivered male twins. The two newborns weighed 790 and 870 g, respectively. To our knowledge, this is the first report of four pregnancies in hemodialysis including one twin pregnancy. The incidence of pregnancy and a better outcome in patients on hemodialysis has increased in recent years but a tight coordination between nephrologists and obstetricians is essential.