Deletion of CPEB1 Gene: A Rare but Recurrent Cause of Premature Ovarian Insufficiency

CONTEXT

Premature ovarian insufficiency (POI) may be secondary to chemotherapy, radiotherapy, or environmental factors. Genetic causes are identified in 20-25% of cases, but most POI cases remain idiopathic.

OBJECTIVE

This study aimed to identify new genes involved in POI and to characterize the implication of CPEB1 gene in POI.

DESIGN AND SETTING

This was a case report and cohort study replicate conducted in academic medical centers.

PATIENTS AND METHODS

A deletion including CPEB1 gene was first identified in a patient with primary amenorrhea. Secondly, 191 sporadic POI cases and 68 familial POI cases were included. For each patient, karyotype was normal and FMR1 premutation was excluded. Search for CPEB1 deletions was performed by quantitative multiplex PCR of short fluorescent fragments or DNA microarray analysis. Gene sequencing of CPEB1 was performed for 95 patients.

RESULTS

We identified three patients carrying a microdeletion in band 15q25.2. The proximal breakpoint, for the three patients, falls within a low-copy repeat region disrupting the CPEB1 gene, which represents a strong candidate gene for POI as it is known to be implicated in oocyte meiosis. No mutation was identified by sequencing CPEB1 gene. Therefore, heterozygous deletion of CPEB1 gene leading to haploinsufficiency could be responsible for POI in humans.

CONCLUSION

Microdeletions of CPEB1 were identified in 1.3% of patients with POI, whereas no mutation was identified. This microdeletion is rare but recurrent as it is mediated by nonallelic homologous recombination due to the existence of low-copy repeats in the region. This result demonstrates the importance of DNA microarray analysis in etiological evaluation and counseling of patients with POI.

Non-invasive prenatal testing for trisomy 21 based on analysis of cell-free fetal DNA circulating in the maternal plasma

OBJECTIVE

By-the-book implementation of non-invasive prenatal test and clinical validation for trisomy 21.

STUDY DESIGN

Publicly funded prospective study of 225 cases. Women at risk for trisomy 21 > 1/250 based on combined ultrasound and serum markers during first or second trimester were eligible following an informed consent. The technique was established from the available literature and performed on 10 mL of venous blood collected prior to chorionic villus sampling or amniocentesis. Investigators were blinded to the fetal karyotype. Results were expressed in Z-scores of the percentage of each chromosome.

RESULTS

Among 976 eligible cases, 225 were processed: 8 were used for pretesting phase and 23 to build a reference set. One hundred thirty six euploid cases and 47 with trisomy 21 were then run randomly. Eleven cases yielded no result (4.8%). Z-scores were above 3 (7.58+/-2.41) for chromosome 21 in all 47 trisomies and in none of the euploid cases (0.11+/-1.0). Z-scores were within normal range for the other chromosomes in both groups. Using a cut-off of 3, sensitivity and specificity were of 100% 95% CI [94.1, 100] and 100% 95% CI [98, 100], respectively.

CONCLUSION

Non-invasive prenatal test for trisomy 21 is a robust strategy that can be translated from seminal publications. Publicly funded studies should refine its indications and cost-effectiveness in prenatal screening and diagnosis. © 2015 John Wiley & Sons, Ltd.

Expanding the clinical and neuroradiologic phenotype of primary microcephaly due to ASPM mutations

OBJECTIVE

To determine the spectrum of clinical, neuropsychological, and neuroradiologic features in patients with autosomal recessive primary microcephaly (MCPH) due to ASPM gene mutations.

METHODS

ASPM was sequenced in 52 unrelated MCPH probands. In patients with ASPM mutations, we evaluated the clinical phenotype, cognition, behavior, brain MRI, and family.

RESULTS

We found homozygous or compound heterozygous ASPM loss-of-function mutations in 11 (22%) probands and 5 siblings. The probands harbored 18 different mutations, of which 16 were new. Microcephaly was severe after 1 year of age in all 16 patients, although in 4 patients the occipital-frontal circumference (OFC) at birth was decreased by only 2 SD. The OFC Z score consistently decreased after birth. Late-onset seizures occurred in 3 patients and significant pyramidal tract involvement in 1 patient. Intellectual quotients ranged from borderline-normal to severe mental retardation. Mild motor delay was noted in 7/16 patients. Language development was delayed in all patients older than 3 years. Brain MRI (n = 12) showed a simplified gyral pattern in 9 patients and several malformations including ventricle enlargement (n = 7), partial corpus callosum agenesis (n = 3), mild cerebellar hypoplasia (n = 1), focal cortical dysplasia (n = 1), and unilateral polymicrogyria (n = 1). Non-neurologic abnormalities consisted of short stature (n = 1), idiopathic premature puberty (n = 1), and renal dysplasia (n = 1).

CONCLUSIONS

We provide a detailed description of features associated with ASPM mutations. Borderline microcephaly at birth, borderline-normal intellectual efficiency, and brain malformations can occur in ASPM-related primary hereditary microcephaly.