Prenatal Diagnosis and Genetic Analysis of a Fetus with Joubert Syndrome. Biomed Res Int. 2018;2018:7202168. [PMID: 29955609 PMCID: PMC6000882 DOI: 10.1155/2018/7202168]

High Incidence of CPLANE1-Related Joubert Syndrome in the Products of Conceptions from Early Pregnancy Losses

Background

The fetal monogenic causes of early pregnancy losses (EPLs) are mainly unknown, with only a few articles on the subject published. In our previous study of EPLs using whole-exome sequencing analysis, we confirmed a genetic diagnosis of CPLANE1-related Joubert syndrome (JS) in three EPLs from two couples and identified a relatively common CPLANE1 allele among our population (NM_001384732.1:c.1819delT;c.7817T>A, further after referred as “complex allele”). Pathogenic variants in the CPLANE1 (C5orf42) gene are reported to cause JS type 17, a primary ciliopathy with various system defects.

Aims

To examine the hypothesis that the CPLANE1 “complex allele,” whether homozygous or compound heterozygous, is a common cause of EPLs in our population.

Study Design

Cohort study/case-control study.ontrol study.

Methods

In this study, we used polymerase chain reaction-based methods to screen for CPLANE1 “complex allele” presence among 246 euploid EPLs (< 12 gestational weeks) from families in North Macedonia. We also investigated the impact of this allele in 650 women with EPLs versus 646 women with no history of pregnancy loss and at least one livebirth, matched by ethnic origin.

Results

We found a high incidence of JS in the total study group of EPLs (2.03%), with a considerably higher incidence among Albanian families (6.25%). Although not statistically significant, women with EPLs had a higher allele frequency of the CPLANE1 “complex allele” (AF = 1.38%) than the controls (AF = 0.85%; p = 0.2). Albanian women had significantly higher frequency of the “complex allele” than the Macedonians (AF = 1.65% and 0.39%, respectively; p = 0.003).

Conclusion

To the best of our knowledge, this is the highest reported incidence of fetal monogenic disease that might cause EPLs. Targeted screening for the CPLANE1 “complex allele” would be warranted in Albanian ethnic couples because it would detect one JS in every 16 euploid EPLs. Our findings have a larger impact on the pathogenesis of pregnancy loss and contribute to a better understanding of the pathogenicity of the variants in the CPLANE1 gene.

Novel variant CPLANE 1: c.5051C>A (p.Ser1684Ter) in an Indian neonate with Joubert syndrome

Joubert syndrome (JS) is a rare ciliopathy that presents with the triad of hypotonia, developmental delay and molar tooth sign (MTS) in brain MRI. Next-generation sequencing has identified about 35 genes which are known to cause JS of which CPLANE 1 mutation is found in 8%-10% of cases. We report a case of JS in an Indian neonate who presented with hypotonia, dysmorphic facies, polydactyly, syndactyly and occipital encephalocele. MRI of the brain revealed MTS, and compound heterozygous mutations in CPLANE 1 gene were detected by clinical exome sequencing, one of them a novel variant CPLANE 1: c.5051C>A (p.Ser1684Ter) in exon 26, which was inherited from the parents.

Novel compound heterozygous CPLANE1 variants identified in a Chinese family with Joubert syndrome

Joubert syndrome (JS) and JS-related disorders (JSRD) are a group of neurodevelopmental diseases that share the "molar tooth sign" on axial brain magnetic resonance imaging (MRI), accompanied by cerebellar vermis hypoplasia, ataxia, hypotonia, and developmental delay. To identify variants responsible for the clinical symptoms of a Chinese family with JS and to explore the genotype-phenotype associations, we conducted a series of clinical examinations, including blood tests, brain MRI scans, ultrasound imaging, and ophthalmologic examination. Genomic DNA was extracted from the peripheral blood of the six-person family, and the pathogenic variants were detected by whole-exome sequencing (WES) and verified by Sanger sequencing. WES revealed two novel compound heterozygous variants in CPLANE1: c.1270C>T (p.Arg424*) in exon 10 and c.8901C>A (p.Tyr2967*) in exon 48 of one child, inherited from each parent. Both variants were absent in ethnically matched Chinese control individuals and were either absent or present at very low frequencies in public databases, suggesting that these variants could be the pathogenic triggers of the JS phenotype. Notably, these CPLANE1 sequence variants were related to the pathogenesis of autosomal recessive JS in this study. The newly discovered variants expand the mutation spectrum of CPLANE1, which assists in understanding the molecular mechanism underlying JS and improving the recognition of genetic counseling, particularly for families with a history of autosomal recessive JS.

OFD1 mutation induced renal failure and polycystic kidney disease in a pair of childhood male twins in China

BACKGROUND

Oral-facial-digital syndrome type 1 (OFD1) is a rare ciliopathy mainly with an X-linked dominant pattern of inheritance, which is caused by mutations in the OFD1 gene. The OFD1 protein is located within the centrosomes and basal bodies of the primary cilia. It is reported that approximately 15%–50% cases of OFD1 progress to end-stage renal disease (ESRD) following development of polycystic kidney diseases (PKD). Here we report a pair of childhood male twins who presented only renal failure and PKD caused by an OFD1 mutation in China.

CASE SUMMARY

A pair of 14-year male twins were hospitalized with a complaint of abnormal renal function for nine days. They both complained of ankle pain for 3 mo vs 2 wk, respectively. They denied fever, abdominal pain, daytime or nighttime enuresis, urgency, dysuria, or gross hematuria. Laboratory tests at a local hospital showed renal failure (serum creatinine 485 μmol/L vs 442 μmol/L, blood urea nitrogen 14.7 mol/L vs 14.5 mol/L) and anemia (hemoglobin 88 g/L vs 98 g/L). The twins are monozygotic. There was no abnormal birth, past medical, or family history. Clinical data were analyzed and genetic analysis on PKD was carried out in the twins by next-generation sequencing. The results showed that the twins presented low-molecular-weight proteinuria, hyposthenuria, anemia, renal failure, and renal polycystic changes. Genetic tests showed that the twins both carried a hemizygous mutation in exon 19 c.2524G>A (p. G842R) of the OFD1 gene. Their mother heterozygously carried the same mutation as the twins but was without any phenotypes while their father was normal.

CONCLUSION

We have reported a pair of childhood male twins with an OFD1 mutation who presented ESRD and PKD but without any other phenotypes of OFD1 in China.

Diagnostic assessment of foetal brain malformations with intra-uterine MRI versus perinatal post-mortem MRI

PURPOSE

To evaluate differences in diagnostic yield of intra-uterine foetal (iuMR) and post-mortem MRI (PMMR) for complex brain malformations, using autopsy as the reference standard.

METHODS

In this retrospective, multicentre study spanning 2 years, we reviewed 13 terminated singleton pregnancies with a prenatal ultrasound finding of complex foetal cerebral abnormalities, referred for both iuMR and PMMR. The iuMR and PMMR studies of the brain were reported independently by two groups of radiologists, blinded to each other's reports. Descriptive statistics were used to compare differences in intracranial abnormalities with autopsy (and genetic testing, where present) as reference standard.

RESULTS

The median gestational age at termination was 24.6 weeks (IQR 22-29) with median time between delivery and PMMR of 133 h (IQR 101-165). There was full concordance between iuMR and PMMR findings and autopsy in 2/13 (15.3%) cases. Partial concordance between both imaging modalities was present in 6/13 (46.2%) and total discordance in the remainder (5/13, 38.5%). When compared to autopsy, PMMR missed important key findings specifically for neuronal migration and cerebellar anomalies, whereas iuMR appeared to overcall CSF space abnormalities which were less crucial to reaching the final overall diagnosis.

CONCLUSIONS

iuMR should be performed to improve foetal phenotyping where there is a prenatal ultrasound for complex foetal brain abnormalities. Reliance on PMMR alone is likely to result in misdiagnosis in a majority of cases.