Pontocerebellar hypoplasia type 1 for the neuropediatrician: Genotype-phenotype correlations and diagnostic guidelines based on new cases and overview of the literature

Pontocerebellar hypoplasia type 1 (PCH1) is a major cause of non-5q spinal muscular atrophy (SMA). We screened 128 SMN1-negative SMA patients from Bulgaria for a frequent mutation -p.G31A in EXOSC3, and performed a literature review of all genetically verified PCH1 cases. Homozygous p.G31A/EXOSC3 mutation was identified in 14 Roma patients, representing three fourths of all our SMN1-negative Roma SMA cases. The phenotype of the p.G31A/EXOSC3 homozygotes was compared to the clinical presentation of all reported to date genetically verified PCH1 cases. Signs of antenatal onset of disease present at birth were common in all PCH1 sub-types except in the homozygous p.D132A/EXOSC3 patients. The PCH1sub-types with early death (between ages 1 day and 17 months), seen in patients with p.G31A/EXOSC3 or SLC25A46 mutations have a SMA type 1-like clinical presentation but with global developmental delay, visual and hearing impairment, with or without microcephaly, nystagmus and optic atrophy. Mutations with milder presentation (homozygous p.D132A/EXOSC3 or VRK1) may display additionally signs of upper motor neuron impairment, dystonia or ataxia and die at age between 5 and 18 years. Other EXOSC3 mutations and EXOSC8 cases are intermediate - SMA type 1-like presentation, spasticity (mostly in EXOSC8) and death between 3 months and 5 years. There is no correlation between neurological onset and duration of life. We add marble-like skin and congenital laryngeal stridor as features of PCH1. We show that imaging signs of cerebellar and pontine hypoplasia may be missing early in infancy. EMG signs of anterior horn neuronopathy may be missing in PCH1 patients with SLC25A46 mutations. Thus, there is considerable phenotypic variability in PCH1, with some cases being more SMA-like, than PCH-like. Detailed clinical evaluation and ethnicity background may guide genetic testing and subsequent genetic counseling.

Chlamydia psittaci genotype B in a pigeon (Columba livia) inhabiting a public place in San José, Costa Rica

Human chlamydiosis is a zoonotic disease of avian origin caused by Chlamydia psittaci. The highest infection rates have been detected in parrots (Psittacidae) and pigeons (Columbiformes), the latter most frequently carry the genotypes B and E. These genotypes have been shown to also infect humans. Because pigeons (Columba livia) cohabit with humans in urban areas, C. psittaci present in the dust from dry feces of infected pigeons may be transmitted by inhalation and represent a significant public health problem. Between 2012 and 2013 a total of 120 fecal samples were collected from pigeons at four public places (Plaza de la Cultura, Parque Morazán, Parque Central de Guadalupe, Plaza de las Garantías Sociales) in San José, Costa Rica. A nested polymerase chain reaction (PCR) was used to amplify a region of the outer membrane protein A gene of C. psittaci. Only one sample was positive in PCR and the positive sample was further subjected to sequencing and genotyping. Sequencing identified this sample as C. psittaci genotype B. This study is the first report to show the presence of this organism in pigeons of Costa Rica, and shows that the infected pigeons may represent a significant risk for humans who visit public places that are inhabited by pigeons.

Chlamydia psittaci genotype B in a pigeon (Columba livia) inhabiting a public place in San José, Costa Rica

Human chlamydiosis is a zoonotic disease of avian origin caused by Chlamydia psittaci. The highest infection rates have been detected in parrots (Psittacidae) and pigeons (Columbiformes), the latter most frequently carry the genotypes B and E. These genotypes have been shown to also infect humans. Because pigeons (Columba livia) cohabit with humans in urban areas, C. psittaci present in the dust from dry feces of infected pigeons may be transmitted by inhalation and represent a significant public health problem. Between 2012 and 2013 a total of 120 fecal samples were collected from pigeons at four public places (Plaza de la Cultura, Parque Morazán, Parque Central de Guadalupe, Plaza de las Garantías Sociales) in San José, Costa Rica. A nested polymerase chain reaction (PCR) was used to amplify a region of the outer membrane protein A gene of C. psittaci. Only one sample was positive in PCR and the positive sample was further subjected to sequencing and genotyping. Sequencing identified this sample as C. psittaci genotype B. This study is the first report to show the presence of this organism in pigeons of Costa Rica, and shows that the infected pigeons may represent a significant risk for humans who visit public places that are inhabited by pigeons.

[Maternal biochemical screening -- an approach for genetic prevention. part 1. first and second trimester screening]

The aim is to perform our eight-year experience on prenatal (matemal) screening for Down syndrome (DS).

METHODS

Pregnant women underwent screening in second trimester (ST2) - 14(+4)-19(+3) gestational week using serum AFP and free beta-hCG biochemical markers. A more sensitive first trimester test has been implemented in 11(+0)-13(+6) gestational weeks since the end of 2009. This combined screening test (CST1) was based on US measurements of NT (nuchal translucency) and NB (nasal bones) supplemented by biochemical markers of serum free beta-hCG and PAPP-A. Uniform methodology, web-based software and system for laboratory quality control had been used. False positive ratios for DS were estimated at cut-offs 1/250 for Down syndrome and 1/100 for Edwards syndrome.

RESULTS

The test was performed on 17 468 pregnant women: 13 016 by biochemical screening 2 test (BHS2) and 4452 by first trimester test CST1. High risk for a chromosome disorder by BHS2 test was found in 1097 (8,4%) cases (5,96% < 35 years and 21,13% > 35 years). 7 fetuses were diagnosed with chromosome disease (5 fetuses with trisomy 21,1 - trisomy 18 and 1 - triploid); false positive were 1090 (8,4%). High risk for a chromosome disorder by CST1 test was found in 102 (2,3%) cases. 4 affected fetuses were diagnosed (3 with trisomy 21 and 1 with trisomy 13). Verified diagnosis for DS by first and second trimester tests were 43% (3 out of 7 cases) with 57% false negative results and 45,5% (6 out of 11 cases) with 54,5% false negative results respectively. Description of biochemical values/MoMs and US measurements are applied.

CONCLUSIONS

We comment on the importance of US measurements in CST1 test and correct analysis of biochemical and US markers in counseling of every individual patient, beyond final risk number.

[Maternal biochemical screening -- an approach for genetic prevention. part 2. sequential approach with integrated risk assessment]

Performance of 2,5 year experience onprenatal (maternal) screening by integrated risk for Down syndrome and Edwards syndrome is presented in pregnant women underwent first (11(+0)-13(+6) g.w) and second trimester screening (14(+4)-19(+3) g.w), assessed by an integrated risk. Since the end of 2010 the most common strategy has been combination of both risks after contingent screening approach (serummarkers and US measurments from first test with indication to second trimester screening if the risk is intermediate or high and CVS diagnosis has been refused). Serummarkers were measured by fluorimetric immunoassay (Delfia) and risks were calculated using LifeCycle 3.2 software.

RESULTS

The test was performed on 491 women, less than 4452 and 13 016 women first and second trimester respectively. We found highrisk for a chromosome disorder in 32 (6,5%) cases: 19 (6,35%) women < 35 and 13 (6,7%) women > 35). Diagnosis of a chromosome diseases was found in 4 fetuses out of 32 (12,5%): 3 fetuses with trisomy 21 and 1 with trisomy 18. False positive results were found in 28 out of 491 (5,7%) women. Verified diagnosis on lyfor DS was found in 3 out of 4 cases (75% sensitivity), and false negative results in 25%. Discussion is focused on the comparison of the screening approaches - the sensitivity, limitation sand the step wise sequential testing way with integrated risk of achieving a high performance of screening.

[The experience in genetic laboratory Varna in amniocentesis and genetic analysis for the period 2006-2010]

The aim of this report is to present and discuss the results from diagnostic amniocenteses, performed in Varna. The test started as a part of a prophylaxis program for pregnant women with calculated high risk for chromosomal disorders after a screening test. Amniocentesis was performed in total of 283 pregnant women. Of all patients who underwent the screening test, amniocentesis was performed in 1.55% of women under 36 years of age and 5.0% of women over 36 years. In the selected group with calculated high risk for chromosomal disorder these percentages were 28.5% and 26% respectively. Fetal chromosomal disorder was found in 5% (in 7 out of 141) in women under 36 and 3.82% (in 7 out of 83) in women over 36 years. Genetic tests (DNA and cytogenetic analysis) of amniocytes revealed chromosomal disorders in 16 (5.65%) fetuses (8 with trisomy 21, 3 with trisomy 18, 1 with trisomy 13, 1 case with triploidy, 3 cases with structural chromosomal rearrangement). Three additional amniocenteses were performed, indicated by family history of monogenic disorder (thalassaemia, spinal muscular atrophy). The effect of the introduced method for prenatal diagnosis, its interaction with the screening tests and their future as genetic prophylaxis program are discussed.

[The experience of the genetic laboratory in Varna on maternal serum screening for a six year period]

The aim of the presentation is to report the results of the Genetic laboratory in University hospital "St. Marina" Varna on second (15-19 gw) and first trimester (12-14 gw) maternal serum screening for common chromosome disorders, for the period 2005-2010. The test was performed on 10741 pregnant women from 8 regions of North-Eastern Bulgaria: 9743 women were screened in the second trimester (8251 at the age < 36 and 1492 at the age > 36) and 998 women - in the first trimester (827 at the age < 36 and 171 at the age > 36). The fluorimetric dual method was based on biochemical markers; software calculated risk as function of precise gestational age, maternal weight and age. The most common strategy was to combine the risk as determined from first and second trimester screening test in a sequential manner. High risk for a chromosome disorder (a risk above 1:250) was found by second trimester screening in 784 (8,04%): 488 (5,91%) <36 and 296 (19,83%) >36. The most recent first trimester screen test, which have been involved in the laboratory since April 2010 detected 7 (0,84%) and 23 (13,45%) women respectively to the age groups with increased risk for a chromosome disease. Additional ultrasonographic scan confirmed the biochemical risk for a serious Neural Tube/Abdomainal Wall defects in 5 out of 32 fetuses with increased risk for these defects; other 3 fetuses were detected to be involuntary miscarried as "missed abortion", 1 triploidy included. We comment on the sensitivity, limitations and the stepwise sequential testing way of achieving a high performance of screening for chromosome diseases based on preliminary information to pregnant women on different options for a contemporary approach for genetic prevention.

[Active screening for genetic pathology in newborns. II. Genetic counseling and prenatal diagnosis in high risk families]

Active screening for genetic pathology over a period of 12 years (1990-2001) involved examination of 29629 newborns at the Clinic of Obstetrics and Gynaecology. Congenital anomalies were detected in 1244 cases (live-, stillbirths and terminated pregnancies) which gives an average incidence rate of 42.0 per 1000 among the studied population. Chromosomal abnormalities were diagnosed in 70 cases (5.6%), single gene conditions--in 164 cases (13.2%), multifactorially determined conditions--in 449 cases (36.1%). The total genetic contribution of all recognized cases with genetic conditions was 54.9% (683 cases). Genetic counseling was provided to 560 out of 1244 (45%) couples who given births to affected children. During that period prenatal diagnosis was performed on 110 (44%) pregnancies and most of them (90%) ended successfully (healthy child was born). Our strategy for identifying CD by active screening enabled us to provide more accurate genetic counselling and prenatal diagnosis for genetic diseases. Screening of newborn population is likely to be an effective and necessary service.

[Postnatal screening for congenital anomalies--the possibility of detecting families at high genetic risk]

The aim of the study was to present out experience with the registration of congenital anomalies (CA) and to assess the effect of the preventive genetic-consultative activities in affected families. In the period 1990-1996, 19174 infants born or hospitalized at the Clinic of Obstetrics, Pleven were screened for CA, showing frequency of 26.1%. Structural analysis of the CA is presented. 226 out of 500 (45%) families with and affected child were consulted by a geneticist. Data an prenatal diagnosis (PD) offered to 142 families at high risk and their reproductive decision are submitted. The low rate of families made use of invasive PD is pointed out; the real benefits of ultrasonography as a screening test for detection of fetal anomalies has been recommended.

[The role of chromosome anomalies in the origin of reproductive failures]

The results from chromosomal analysis of 185 couples, studied on the occasion of reproductive failures (RF), such as sterility, spontaneous abortions, stillbirths and malformed children are presented. Twenty nine couples (15.68%) with one of spouses--a carrier of a chromosomal anomaly (CA) are established. CA types include: aneuploidy--2, mosaic--5, Robertson's translocation--3, non-Robertson's translocation--7, and pericentric inversion--12. Recognition of genetic conditions is vital for accurate assessment of recurrence risks and in order in some instances, to provide specific prenatal diagnosis.