Short stature and dysmorphic features in Asian Indian siblings with DAAM2-associated steroid-resistant nephrotic syndrome: Expansion of the phenotypic spectrum or a blended phenotype?

Variants in more than 60 different genes, most of which code for podocyte-related proteins, have been found to be associated with monogenic forms of nephrotic syndrome (NS). Biallelic variants in DAAM2, a member of the formin family, were recently identified to cause autosomal recessive (AR) NS type 24 in four unrelated families with steroid-resistant nephrotic syndrome (SRNS). This case report represents only the fifth reported family of DAAM2-associated NS and the first from India, with two sibs who presented with a complex phenotype characterized by steroid-resistant nephrotic syndrome, short stature, dysmorphic facial features, deep-set toenails, myopia, increased thickness of the calvarium of the skull, and sloping ribs. Both sibs were found to have a homozygous likely pathogenic nonsense variant c.196C>T (p.Arg66Ter; NM_001201427.2) in exon 3 of the DAAM2 gene through whole exome sequencing. The dysmorphic features could possibly be part of the DAAM2-related phenotype which has hitherto not been reported or could represent a blended phenotype, with the extrarenal manifestations resulting from a yet to be identified coexisting genetic condition.

Monogenic conditions and central nervous system anomalies: A prospective study, systematic review and meta-analysis.

OBJECTIVES: Determine the incremental diagnostic yield of prenatal exome sequencing (pES) over chromosome microarray (CMA) or G-banding karyotype in fetuses with central nervous system (CNS) abnormalities. METHODS: Data were collected via electronic searches from January 2010 to April 2022 in MEDLINE, Cochrane, Web of Science and EMBASE. The NHS England prenatal exome cohort was also included. Incremental yield was calculated as a pooled value using a random-effects model. RESULTS: Thirty studies were included (n = 1583 cases). The incremental yield with pES for any CNS anomaly was 32% [95%CI 27%-36%; I2 = 72%]. Subgroup analysis revealed apparent incremental yields in; (a) isolated CNS anomalies; 27% [95%CI 19%-34%; I2 = 74%]; (b) single CNS anomaly; 16% [95% CI 10%-23%; I2 = 41%]; (c) more than one CNS anomaly; 31% [95% Cl 21%-40%; I2 = 56%]; and (d) the anatomical subtype with the most optimal yield was Type 1 malformation of cortical development, related to abnormal cell proliferation or apoptosis, incorporating microcephalies, megalencephalies and dysplasia; 40% (22%-57%; I2 = 68%). The commonest syndromes in isolated cases were Lissencephaly 3 and X-linked hydrocephalus. CONCLUSIONS: Prenatal exome sequencing provides a high incremental diagnostic yield in fetuses with CNS abnormalities with optimal yields in cases with multiple CNS anomalies, particularly those affecting the midline, posterior fossa and cortex.

Muscle spasms as presenting feature of Nivelon-Nivelon-Mabile syndrome.

Hedgehog acyltransferase gene (HHAT)-associated Nivelon-Nivelon-Mabile syndrome (NNMS) is a rare genetic disorder of multiple system involvement with microcephaly, central nervous system malformations, skeletal dysplasia, and 46,XY sex reversal. Other variable and inconsistent features reported in this disorder are muscle spasms, facial dysmorphism, prenatal onset growth restriction, microphthalmia, and holoprosencephaly. This is the sixth postnatal reported patient with biallelic variants in HHAT gene, who presented with microcephaly, short stature, muscle hypertrophy, muscle spasms, and facial dysmorphism. The most prominent and presenting finding in this patient were muscle hypertrophy and muscle spasms which had a clinical response to phenytoin and acetazolamide treatment. Our report emphasizes the phenotypic variability of NNMS and further reiterates muscle spasms as an important clinical manifestation of this extremely rare condition.

Prenatal phenotype of FBXL4-associated encephalomyopathic mitochondrial DNA depletion syndrome-13.

FBXL4 -associated encephalomyopathic mitochondrial DNA depletion syndrome-13 (MTDPS13) is a rare genetic disorder characterized by early neonatal onset of encephalopathy, seizures, lactic acidosis, hypotonia, dysmorphism, and severe global developmental delay. Prenatal phenotype of molecularly confirmed MTDPS13 has not been well studied. This is the case report of a non-consanguineously conceived fetus ascertained first at 20 weeks of gestation with multiple soft markers. Follow-up fetal ultrasonogram at 26 weeks revealed periventricular cysts, periventricular echogenicity, ventriculomegaly, thin corpus callosum, mega cisterna magna, and large cavum. Fetal MRI confirmed these findings. Postnatally, the baby had clinical and biochemical findings indicative of a mitochondriopathy and died on neonatal day 3. Whole exome sequencing on stored amniotic fluid DNA confirmed the diagnosis of encephalomyopathic mitochondrial DNA depletion syndrome-13 (MTDPS13). This report presents the prenatal phenotype of this rare mitochondriopathy, which has been recognized primarily in postnatal patients. The brain imaging findings in the reported fetus indicate that MTDPS13 is associated with progressive neurological involvement and brain tissue destructive changes starting as early as the second trimester of pregnancy. The case also raises concerns regarding the association of so-called soft markers, which were the only initial finding in this case, with severe monogenic diseases.

Fetal phenotypes of Mendelian disorders: A descriptive study from India.

OBJECTIVE: Exome sequencing (ES)-based diagnosis of Mendelian diseases in the fetus is limited by paucity of phenotypic information. This study reports the comprehensive phenotypes of some fetuses with Mendelian disorders. METHODS: Next generation technology-based sequencing of all coding regions of the genome (Exome sequencing) or targeted gene sequencing using Sanger or next generation platforms was performed in a cohort of deeply phenotyped, cytogenetically normal fetuses with morphological defects. Prenatal ultrasonographic phenotypes and postmortem details including dysmorphology, histopathology, and radiography were ascertained. Novel candidate genes, novel/unusual findings, and unusual genotypes in cases with confirmed Mendelian disorders are described. RESULTS: Of the 102 fetuses sequenced, 45 (44%) achieved definitive diagnosis of a Mendelian disorder with 50 pathogenic/likely pathogenic variants. The majority (87%) were autosomal recessive, 69% families were consanguineous, and 54% variants were novel. Dysmorphic syndromes, skeletal dysplasias, and metabolic disorders were the commonest disease categories, ciliopathies and dystroglycanopathies, commonest molecular categories. We describe the first fetal description of six monogenic diseases, and nine cases with novel histological findings. Nineteen cases had novel/unusual findings. CONCLUSION: This cohort demonstrates how deep fetal phenotypes of some Mendelian disorders can show novel/unusual findings, which have important implications for prenatal diagnosis of these conditions.

Recurrent Vein of Galen Aneurysmal Malformation as a Presentation of Hereditary Hemorrhagic Telangiectasia.

Introduction: Vein of Galen malformation (VGM) results from an aneurysmal aberration with an arteriovenous shunting of blood and is the most frequent arteriovenous malformation in infants and fetuses. The congenital malformation develops during weeks 6-11 of fetal development. Infants often die from high-output congestive heart failure. VGM is mostly considered as a sporadic condition with minimal recurrence risk in subsequent pregnancies. Mendelian forms of VGM have rarely been described as infrequent phenotypic presentations of 2 disorders: capillary malformation-arteriovenous malformation syndrome (RASA1, EPHB4) and hereditary hemorrhagic telangiectasia (ENG, ACVRL1, and SMAD4), both showing autosomal dominant inheritance. Case Presentation: Here, we report on a consanguineous couple with recurrent VGM in 2 pregnancies. Both partners were found to be affected by hereditary hemorrhagic telangiectasia due to a known pathogenic heterozygous c.790G>A (p.Asp264Asn) variant in ENG. Fetal DNA was unavailable, however in view of the mild phenotype in the couple, along with the severe prenatal presentation in 2 pregnancies, the fetus was presumed to be homozygous for the ENG variant. A subsequent pregnancy revealed a fetus heterozygous for the variant, which had an uneventful perinatal course. Conclusion: This report highlights a severe perinatal lethal phenotype due to biallelic variants in a gene hitherto known to cause an autosomal dominant disorder.

Clinical and Surgical Insights on Bilateral Total Knee Arthroplasty in Ochronotic Arthropathy: A Case-based Review.

Introduction: Ochronotic arthropathy (OcA) is a consequence of alkaptonuria, a rare systemic-inherited metabolic disorder leading to accumulation of homogentisic acid in articular cartilage and subsequent early degeneration of the joints. Only few cases of OcA managed with bilateral total knee arthroplasty (TKA) has been described in the literature so far. We aim to discuss surgical pearls, pitfalls, and clinical outcome of OcA of knees managed with simultaneous bilateral TKA. Case Presentation: The patient was a 52-year-old female presented to outpatient facility with severe bilateral knee pain and difficult ambulation. After clinical and radiological diagnosis of osteoarthritis, she was posted for bilateral TKA. During arthrotomy, blackening of articular cartilage, quadriceps and patellar tendon, and synovium was noted. Subchondral bone was free of pigmentation though, seemed osteopenic while taking bone cuts. Right knee was implanted with cruciate retaining components with ultracongruent insert; while on the left side, posterior stabilized components were used. Diagnosis of ochronosis was made retrospectively with characteristic subtle pigmentation of nails, palms, pinnae, and urine homogentisic levels. Two years follow-up of the patient remained satisfactory without any major complications. Conclusion: OcA may present with intra-operative surprise to the surgeon if not anticipated preoperatively. Simultaneous bilateral TKA is safe and effective treatment for end-stage arthritis. However, it is difficult to diagnose it preoperatively; a high clinical suspicion leads to meticulous assessment and counseling regarding potential anesthetic concerns, choice of implant, and possible intra-operative and post-operative complications reported sporadically though.