Development, validation and application of single molecule molecular inversion probe based novel integrated genetic screening method for 29 common lysosomal storage disorders in India.

BACKGROUND: Current clinical diagnosis pathway for lysosomal storage disorders (LSDs) involves sequential biochemical enzymatic tests followed by DNA sequencing, which is iterative, has low diagnostic yield and is costly due to overlapping clinical presentations. Here, we describe a novel low-cost and high-throughput sequencing assay using single-molecule molecular inversion probes (smMIPs) to screen for causative single nucleotide variants (SNVs) and copy number variants (CNVs) in genes associated with 29 common LSDs in India. RESULTS: 903 smMIPs were designed to target exon and exon-intron boundaries of targeted genes (n = 23; 53.7 kb of the human genome) and were equimolarly pooled to create a sequencing library. After extensive validation in a cohort of 50 patients, we screened 300 patients with either biochemical diagnosis (n = 187) or clinical suspicion (n = 113) of LSDs. A diagnostic yield of 83.4% was observed in patients with prior biochemical diagnosis of LSD. Furthermore, diagnostic yield of 73.9% (n = 54/73) was observed in patients with high clinical suspicion of LSD in contrast with 2.4% (n = 1/40) in patients with low clinical suspicion of LSD. In addition to detecting SNVs, the assay could detect single and multi-exon copy number variants with high confidence. Critically, Niemann-Pick disease type C and neuronal ceroid lipofuscinosis-6 diseases for which biochemical testing is unavailable, could be diagnosed using our assay. Lastly, we observed a non-inferior performance of the assay in DNA extracted from dried blood spots in comparison with whole blood. CONCLUSION: We developed a flexible and scalable assay to reliably detect genetic causes of 29 common LSDs in India. The assay consolidates the detection of multiple variant types in multiple sample types while having improved diagnostic yield at same or lower cost compared to current clinical paradigm.

Fetal Pontine Tegmental Cap Dysplasia- A Case Report.

Pontine tegmental cap dysplasia (PTCD) is a very rare hindbrain malformation recently described and the affected children show a bad prognosis. We present this case to increase the awareness of this rare condition and to highlight the importance of early prenatal diagnosis. A 25 years old female with 22 weeks gestation was referred after sonography for fetal magnetic resonance imaging (MRI) in the evaluation of cerebellar hypoplasia. Prenatal MRI confirmed cerebellar hypoplasia. Follow up postnatal MRI showed flattening of the ventral pons, beak-like tissue in the posterosuperior pons suggesting the diagnosis of PTCD. In retrospect the fetal MR images revealed features consistent with PTCD. To the best of our knowledge, this is the fifth prenatal case and with the earliest gestational age of 22 weeks.

Imaging spectrum of posterior fossa anomalies on foetal magnetic resonance imaging with an algorithmic approach to diagnosis.

Posterior fossa abnormalities are one of the most common indications for performing foetal magnetic resonance imaging (FMRI). Ultrasonography is the initial imaging modality for assessment of foetal posterior fossa. Abnormal findings on ultrasonography warrant further evaluation with FMRI because it offers excellent soft-tissue contrast resolution and multiplanar capabilities. The neurological prognosis of different posterior fossa anomalies varies widely. FMRI plays a crucial role in confirming the diagnosis, assessing the prognosis, and counselling patients regarding continuation of pregnancy and possible post-natal developmental outcome. In this review we present the imaging spectrum of posterior fossa anomalies that readers can encounter in practice, highlight salient points in favour of each diagnosis, and provide a simplified algorithmic approach to reach the final diagnosis.

Magnetic Resonance Imaging Findings in Fetal Corpus Callosal Developmental Abnormalities: A Pictorial Essay.

The corpus callosum is the principal supratentorial cerebral commissure, which connects the two cerebral hemispheres in the midline. It is divided into rostrum, genu, body, and splenium. Affected patients may develop mental retardation, dysmorphic features, spasticity, ataxia, or epilepsy. Corpus callosal abnormalities may be isolated or be associated with other anomalies such as sulcal abnormality, ventriculomegaly, cerebellar hypoplasia or cerebellar vermian hypoplasia. Magnetic resonance imaging (MRI) plays a major role in the diagnosis of fetal corpus callosal developmental abnormalities when they are suspected on sonography. This pictorial essay shows the MRI findings in fetal corpus callosal developmental abnormalities in a very systematic manner.

Utility of Various Ultrafast Magnetic Resonance Sequences in the Detection of Fetal Intracranial Hemorrhage.

OBJECTIVE: The aim of this study is to compare the images obtained from standard ultrafast magnetic resonance (MR) imaging sequences with gradient (GRE) sequence images in identifying fetal intracranial hemorrhage (ICH). MATERIALS AND METHODS: MR images of fetal brains with ICH done between October 2012 and September 2015 were reviewed. The images obtained from four ultrafast MR sequences- Turbo Fast Low Angle Shot (Turbo FLASH) T1-weighted images, Half Fourier Acquisition single-shot turbo spin echo (HASTE) T2-weighted images, b0 images of diffusion-weighted imaging (DWI) and b800 images of DWI were compared with images obtained from GRE sequence in depicting fetal ICH. RESULTS: Out of the 212 fetuses during the study period, 15 fetuses had ICH. In the 15 fetuses with ICH as detected on GRE, Grade1 germinal matrix hemorrhage was seen in 5 fetuses, Grade 2 in 4 fetuses, Grade 3 in 3 fetuses, and Grade 4 in two fetuses. Subdural hemorrhage was seen in 1 fetus. In comparison to GRE sequence, b0 of DWI sequence was almost equal in the depiction of ICH. T2 HASTE sequence also delineated hemorrhage, although not as effectively as GRE and b0 images of images DWI. T1 Turbo FLASH and b800 images of DWI were less reliable in the depiction of fetal ICH but were useful in predicting the stage of hemorrhage. CONCLUSION: As compared to GRE sequence, b0 images of DWI followed by HASTE are the two preferred ultrafast sequences in the diagnosis of fetal ICH.

Normative Data of Thyroid Gland Volume in South Indian Neonates and Infants.

OBJECTIVE: To establish normative ultrasound data for thyroid gland volume in South Indian neonates and infants and compare with abnormal sonological features of thyroid in congenital hypothyroidism (CH) to explore thyroid ultrasound utility as a supportive screening tool to newborn screening programs for early detection of CH. METHODS: In view of impact of geo ethnic factors, varying growth velocities and body mass indices of human population worldwide, specific regional, age and gender related reference data for thyroid gland size and volume are vital. This study was an offshoot of ICMR pilot New Born Screening (NBS) project for CH. Formula used for thyroid volume estimation was ellipsoidal formula D1 x D2 x D3 × 0.523. It was a prospective observational study. The neonates who screened negative for Thyroid Stimulating Hormone (TSH) with repeat normal serum TSH and free thyroxine were selected. One hundred fifty seven infants were enrolled which included 99 boys and 58 girls. The study population included children in age groups from 3 d to 1 y six months. RESULTS: Data analysis was done by descriptive method and unpaired t test. Mean thyroid volume was 0.26 ml with 0.27 ml in boys and 0.24 ml in girls. Statistically significant "p value" was noted in single lobe measurements among boys and girls. CONCLUSIONS: Thyroid gland volume normative data play a key role in evaluation of thyroid sonological abnormalities in CH and there is effective utility of ultrasound as a supportive diagnostic and prognostic screening tool for early detection of CH.

Apparent normal arrangement pattern of three-vessel view in a fetus with transposition of great arteries and L-malposed aorta.

Transposition of great arteries (TGA) is more commonly associated with D-malposition of great arteries where anterior aorta produces characteristic "I" sign in the three-vessel view (3VV) in fetal heart imaging. We describe two cases with TGA and L-malposition of aorta where 3VV imaging showed an apparently normal arrangement of vessels while outflow tract imaging proved vital in diagnosing transposition anatomy. Apparently, normal 3VV in the presence of disproportionate vessel caliber and inability to produce normal outflow images should raise the suspicion. Attempts should be made to produce views to show great arteries originating from respective ventricles to rule out ventriculoarterial discordance and to complete segmental analysis.

Persistent Left Superior Vena Cava in Fetuses: An Autopsy Series.

OBJECTIVE: To review fetal autopsy reports with persistent left superior vena cava (PLSVC) and identify its associations. MATERIALS AND METHODS: Autopsy reports of all fetuses diagnosed with PLSVC in our center from January 2011 to December 2015 were reviewed. Fetuses less than 15 weeks gestational age along with autolyzed and damaged hearts were excluded from the study. The study group was compared with controls during this period. RESULTS: Prenatal ultrasound detection rate of PLSVC was 13.06%. All the cases had associated anomalies of which 96% had extra cardiac anomalies and 67% had intrinsic cardiac defects among which septal defects were most common (39.6%). Anomalies of cardiovascular, respiratory, genitourinary and musculoskeletal, hypoplastic thymus and single umbilical artery were significantly higher in the study group. CONCLUSION: This study emphasizes on the importance of improving the technical skill for imaging the three-vessel view as PLSVC seems to have significant associations.

Congenital pseudoaneurysm of mitral-aortic intervalvular fibrosa masquerading as left atrial mass in fetal life.

A 28-week-old fetus was detected to have a single left atrial mass in prenatal ultrasound. Postnatal echocardiography showed an aneurysm between the anterior mitral leaflet and aortic valve, to the left of atrioventricular junction and communicating with the left ventricle through a narrow mouth. It probably originated from the mitral-aortic intervalvular fibrous tissue and an inherent weakness at this site might be the cause. Reported cases of pseudoaneurysm of mitral-aortic intervalvular fibrosa and subvalvular ventricular aneurysms seen following infective endocarditis, surgery, or trauma seem to have a similar anatomical background. This case explains the possibility of congenital aneurysm in this location which needs to be considered a differential diagnosis in similar cases.

Usefulness of fetal autopsy in the diagnosis of blomstrand chondrodysplasia: a report of three cases.

Blomstrand osteochondrodysplasia (BOCD) is a rare autosomal recessive sclerosing skeletal dysplasia characterized by accelerated chondrocyte differentiation. In this article, we discuss three cases where lethal skeletal dysplasia was suspected and Blomstrand dysplasia was diagnosed by autopsy. Antenatal ultrasound findings include increased nuchal translucency, tetramicromelia and polyhydramnios. Radiological hallmark is advanced skeletal maturation and bone sclerosis. Histology of long bones revealed narrow cartilagenous cap and changes in the physeal growth zone which showed severe hypoplasia and disorganization of proliferative phase and hypertrophic phase. Homozygous and compound heterozygous mutations in PTHR1 gene have been implicated in the pathogenesis of this chondrodysplasia.

Spontaneous resolution of Blake's pouch cyst.

Blake's pouch cyst is a rare posterior fossa cystic lesion characterized by posterior ballooning of the superior medullary velum into the cisterna magna. It must be differentiated from severe malformations like inferior vermian hypoplasia and Dandy Walker malformation. We describe a case in which a diagnosis of Blake's pouch cyst was made on prenatal ultrasound and later confirmed by MRI. The cyst showed complete regression on postnatal MRI.

Prenatal diagnosis of restrictive dermopathy.

We report three cases of Restrictive dermopathy from unrelated families. All were small for gestational age with small eyes and open mouth. Taut, stretched skin caused restriction of movements. Clavicular hypoplasia was a consistent radiological feature. Molecular diagnosis in the parents facilitated prenatal diagnosis from chorionic villous sample (CVS) in the subsequent pregnancy.