Dhanya Yesodharan

Eight years experience from a skeletal dysplasia referral center in a tertiary hospital in Southern India: A model for the diagnosis and treatment of rare diseases in a developing country

We report on a series of 514 consecutive diagnoses of skeletal dysplasia made over an 8‐year period at a tertiary hospital in Kerala, India. The most common diagnostic groups were dysostosis multiplex group (n = 73) followed by FGFR3 (n = 49) and osteogenesis imperfecta and decreased bone density group (n = 41). Molecular confirmation was obtained in 109 cases. Clinical and radiographic evaluation was obtained in close diagnostic collaboration with expert groups abroad through Internet communication for difficult cases. This has allowed for targeted biochemical and molecular studies leading to the correct identification of rare or novel conditions, which has not only helped affected families by allowing for improved genetic counseling and prenatal diagnosis but also resulted in several scientific contributions. We conclude that (1) the spectrum of genetic bone disease in Kerala, India, is similar to that of other parts of the world, but recessive entities may be more frequent because of widespread consanguinity; (2) prenatal detection of skeletal dysplasias remains relatively rare because of limited access to expert prenatal ultrasound facilities; (3) because of the low accessibility to molecular tests, precise clinical‐radiographic phenotyping remains the mainstay of diagnosis and counseling and of gatekeeping to efficient laboratory testing; (4) good phenotyping allows, a significant contribution to the recognition and characterization of novel entities. We suggest that the tight collaboration between a local reference center with dedicated personnel and expert diagnostic networks may be a proficient model to bring current diagnostics to developing countries.

Sirenomelia: Case Reports and Current Concepts of Pathogenesis

We present 2 cases of sirenomelia and highlight the recent theories about its pathogenesis. Both cases had a large aberrant abdominal umbilical artery (AAUA) arising from the aorta, suggesting vascular steal as the pathophysiology. However, the bilateral upper limb defects noted in 1 case, the reported 10% association of holoprosencephaly and anencephaly, and the reports of sirenomelia with normal umbilical arteries point to the alternative caudal dysgenesis (CD) theory. This proposes that an insult at the early blastogenic stage interferes with the formation of the notochord, resulting in abnormal development of caudal structures, an AAUA, and occasional neural tube defects. We have also analyzed the implications of the similarities between sirenomelia/CD and the VATER association; the increased risk of CD but not sirenomelia in infants of diabetic mothers; the fact that sirenomelia, holoprosencephaly, and the VATER association are all more common in monozygotic twins; the experimental production of sirenomelia in mice; and the possible genetic implications of the co-occurrence of sirenomelia and CD.

Recurrence of Angelman Syndrome in Siblings: Challenges in Genetic Counseling

The authors report a rare occurrence of two siblings with Angelman syndrome. Their karyotype revealed monosomy of chromosome 15 and a derivative chromosome 1 leading to Angelman syndrome. Their mother was a balanced translocation carrier involving chromosomes 1p and 15p. In her subsequent pregnancy, prenatal karyotype analysis was offered and the fetus was unaffected.

Reciprocal Microduplication of the Williams-Beuren Syndrome Chromosome Region in a 9-Year-Old Omani Boy

BACKGROUND Microdeletions of the 7q11.23 Williams-Beuren syndrome chromosome region (WBSCR) are reported with a frequency of 1 in 10,000, whereas microduplications of the region, although expected to occur at the same frequency, are not widely reported. METHOD We evaluated a 9-year old Omani boy for idiopathic intellectual disability using genetic methods, including multiplex ligation-dependent probe amplification (MLPA), for detection of microdeletions (P064-B3). RESULTS MLPA analysis revealed that the boy has a rare microduplication of the WBSCR. Prominent clinical features include global developmental delay with pronounced speech delay, dysmorphic facies, and autistic features. CONCLUSION Microduplications, in general, are reported at a lesser frequency, perhaps owing to their milder phenotype. Complete genetic assessment in children with idiopathic intellectual disability would help in identifying rare conditions such as duplication of the WBSCR.

Heterozygous Complete NIPBL Gene Deletion in Cornelia de Lange Syndrome: First Case Report from India

Abstract Cornelia de Lange Syndrome-1 (CdLS; OMIM # 122470) is a multisystem, congenital, developmental disorder caused by heterozygous mutation in NIPBL gene on chromosome 5p13. CdLS is characterized by growth and developmental delay, facial dysmorphism, limb abnormality and other organ defects. The condition is mainly caused due to mutation in one of the cohesin ring forming genes. Among NIPBL, SMC1A and SMC3; NIPBL is mainly responsible for causing CdLS. To date molecular data for Indian CdLS patients is not available. Entire NIPBL gene has been screened in 12 children showing CdLS using MLPA in this study. The study reports entire gene deletion in one proband and partial gene deletion in the second proband. The observed deletion was in heterozygous condition in both the cases. The finding was validated by real time PCR.

Subtelomeric rearrangements in Indian children with idiopathic intellectual disability/developmental delay: Frequency estimation & clinical correlation using fluorescence in situ hybridization (FISH)

Background & objectives: Subtelomeres are prone to deleterious rearrangements owing to their proximity to unique sequences on the one end and telomeric repetitive sequences, which increase their tendency to recombine, on the other end. These subtelomeric rearrangements resulting in segmental aneusomy are reported to contribute to the aetiology of idiopathic intellectual disability/developmental delay (ID/DD). We undertook this study to estimate the frequency of subtelomeric rearrangements in children with ID/DD. Methods: One hundred and twenty seven children with idiopathic ID/DD were tested for subtelomeric rearrangements using karyotyping and FISH. Blood samples were cultured, harvested, fixed and GTG-banded using the standard protocols. Results: Rearrangements involving the subtelomeres were observed in 7.8 per cent of the tested samples. Detection of rearrangements visible at the resolution of the karyotype constituted 2.3 per cent, while those rearrangements detected only with FISH constituted 5.5 per cent. Five deletions and five unbalanced translocations were detected. Analysis of parental samples wherever possible was informative regarding the inheritance of the rearrangement. Interpretation & conclusions: The frequency of subtelomeric rearrangements observed in this study was within the reported range of 0-35 per cent. All abnormal genotypes were clinically correlated. Further analysis with array technologies presents a future prospect. Our results suggest the need to test individuals with ID/DD for subtelomeric rearrangements using sensitive methods such as FISH.

Goltz-Gorlin Syndrome: Revisiting the Clinical Spectrum

ObjectiveTo describe the varying phenotypic spectrum of Focal Dermal Hypoplasia (FDH) and to emphasize the need for identifying the condition in mildly affected females which is crucial for offering a prenatal diagnosis in subsequent pregnancy owing to the risk of having a severely affected baby.MethodsThe phenotype-genotype correlation of 4 patients with FDH, over a period of 11 y from the genetic clinic in a tertiary care centre from Kerala, India was done.ResultsAll four mutation proven patients were females (2 adults and 2 children). One of the adult female subjects were mildly affected, though she had a history of having a severely affected female child who expired on day six. Among the 2 affected children, one of them had an unaffected mother and the other had an affected mother.ConclusionsFDH has a wide clinical spectrum from very subtle findings to severe manifestations. The lethality of the condition in males and the disfigurement and multisystem involvement in females highlights the importance of confirmation of diagnosis by molecular analysis so that the family can be offered prenatal diagnosis in subsequent pregnancy.

Coinheritance of biallelic SLURP1 and SLC39A4 mutations cause a severe genodermatosis with skin peeling and hair loss all over the body.

Next-generation sequencing (NGS), especially multi-gene panels and whole-exome sequencing (WES), is a tool for identifying the cause of monogenic disorders and has played a role in uncovering the genetic cause of previously uncharacterized genodermatoses.1 By the application of NGS, the concept of apparently novel or atypical clinical presentations has been challenged by the finding of two or more genetic diagnoses in affected individuals. Approximately 5% of cases in which WES was informative had dual or multiple molecular diagnoses.2 This article is protected by copyright. All rights reserved.

Cortical atrophy and hypofibrinogenemia due to FGG and TBCD mutations in a single family: a case report

BackgroundBlended phenotypes or co-occurrence of independent phenotypically distinct conditions are extremely rare and are due to coincidence of multiple pathogenic mutations, especially due to consanguinity. Hereditary fibrinogen deficiencies result from mutations in the genes FGA, FGB, and FGG, encoding the three different polypeptide chains that comprise fibrinogen. Neurodevelopmental abnormalities have not been associated with fibrinogen deficiencies. In this study, we report an unusual patient with a combination of two independently inherited genetic conditions; fibrinogen deficiency and early onset cortical atrophy.Case presentationThe study describes a male child from consanguineous family presented with hypofibrinogenemia, diffuse cortical atrophy, microcephaly, hypertonia and axonal motor neuropathy. Through a combination of homozygosity mapping and exome sequencing, we identified bi-allelic pathogenic mutations in two genes: a homozygous novel truncating mutation in FGG (c.554del; p.Lys185Argfs*14) and a homozygous missense mutation in TBCD (c.1423G > A;p.Ala475Thr). Loss of function mutations in FGG have been associated with fibrinogen deficiency, while the c.1423G > A mutation in TBCD causes a novel syndrome of neurodegeneration and early onset encephalopathy.ConclusionsOur study highlights the importance of homozygosity mapping and exome sequencing in molecular prenatal diagnosis, especially when multiple gene mutations are responsible for the phenotype.

Plexiform Neurofibroma of Clitoris

The most frequent genital presentation of neurofibromatosis in females is clitoromegaly. We report a case of a 5-year-old girl with neurofibromatosis type 1 with clitoral plexiform neurofibromatosis. Clitoroplasty was done, and the histopathology confirmed the diagnosis. Though rare, plexiform neurofibroma of clitoris should always be considered as a differential diagnosis in children with clitoromegaly before embarking on detailed investigations.