Dhanya Yesodharan

Fat Mass and Obesity‐Associated ( FTO ) gene encodes a versatile RNA‐modifying enzyme that regulates gene expression, RNA processing, and protein synthesis by demethylating different RNA substrates. FTO has a wide range of effects on mammalian physiological functions in regulating fat mass, adipogenesis, and energy homeostasis. Bi‐allelic variants in FTO cause growth failure, developmental delay, and facial dysmorphism. Earlier reported individuals carried variants at critical catalytic sites and had severe developmental phenotypes with early childhood lethality. We report 13 additional individuals from nine families with variable prenatal and postnatal phenotypes with variants in FTO (NM_001080432.3). We add a presumably founder variant c.608 T>C in seven individuals from four Indian families with milder clinical and neuroimaging findings compared to earlier reports. We reviewed genotype‐phenotypes of the current series and previous individuals with FTO‐related developmental disorders. We also document the prenatal phenotypes of FTO variants, thereby expanding the spectrum of FTO‐related developmental anomalies.

Purpose Genotyping of classic congenital adrenal hyperplasia (CAH) due to 21-hydroxylase deficiency (21-OHD) is becoming increasingly significant beyond prenatal counseling in the current era of emerging gene therapy/editing technologies. While the knowledge of common variants helps in designing cost-effective genotyping strategies, limited data are currently available from the Indian subcontinent, especially South India, mainly due to financial constraints. The aim of this study is to assess the genotype of individuals with classic CAH from a South Indian cohort in a cost-effective manner. Methods The genotypes of 46 unrelated subjects with classic CAH were studied through initial multiplex ligation-dependent probe amplification (MLPA) using the SALSA MLPA Probe-mix P050 CAH (MRC Holland). Next-generation sequencing (NGS) was done in 10 subjects, as their MLPA was either negative or showed heterozygous variants. Results The common variants observed in our study population of 46 subjects were large deletions (35.8%), intron 2 variant [c.293-13A/C > G] (35.8%), 8 bp del [c.332_339del p.(Gly111Valfs*21)] (7.7%), and R356W [c.1069 C > T p.(Arg357Trp)] (6.6%). MLPA alone detected pathogenic variants in 78.2% of the initial study samples (36/46). Sequential NGS resulted in a 100% detection rate in our study population. Conclusion MLPA appears to be an effective first genotyping modality for this South Indian cohort due to the high prevalence of large deletions and common variants. MLPA as a first initial screening genotyping test with sequential NGS when required may be a cost-effective and highly sensitive approach to CYP21A2 genotyping in our part of the world and in resource-poor settings.

Objectives To analyse the clinical and molecular spectrum of Lipoprotein Lipase (LPL) deficiency and to highlight the effect of a cost-effective indigenous diet for management of this disorder. Methods This is a single-centre retrospective study. Fifteen patients from 14 kindreds with severe hypertriglyceridemia (more than 1000 mg/dl) were evaluated for a period of 12.5 y at Amrita Institute of Medical Sciences, Kerala, India. Results Thirteen of 15 patients were referred after incidental detection of lipemic plasma, 1/15 had chylothorax in the neonatal period and 1/15 had pancreatitis. The mean age of presentation was 7 mo (ranging from 2 d to 4 y), and 20% of the patients had a positive history of consanguinity. Hepatomegaly (15/15), splenomegaly (9/15) and lipemia retinalis (14/15) were common findings. Lipemia retinalis was a useful non-invasive diagnostic tool. All the patients were subjected to diet modification and followed up at regular intervals. Fourteen of 15 complied with the diet, resulting in a dramatic improvement in the fasting lipid profile; only 1/15 developed pancreatitis. Genetic screening analysis was offered to 14/15 patients (1/15 was lost to follow-up); six different variants were identified, of which two were novel variants. Conclusions Lipemic serum, chylothorax and recurrent pancreatitis in children should raise the suspicion of Lipoprotein Lipase deficiency. Early diagnosis and prompt initiation of a stringent fat-restricted diet are the keys to success for the management of LPL deficiency and prevention of pancreatitis.

Introduction Alkaptonuria (AKU) is a rare metabolic disease. The global incidence is 1:100,000 to 1:250,000. However, identification of a founder mutation in a gypsy population from India prompted us to study the prevalence of AKU in this population and to do molecular typing in referred cases of AKU from the rest of India. Objective To determine the prevalence of AKU in the gypsy population predominantly residing in the seven districts of Tamil Nadu. To determine the molecular characteristic of AKU cases referred to our clinic from various parts of India. Method Urine spot test to detect homogentisic acid followed by quantitative estimation using high-performance liquid chromatography in 499 participants from the gypsy population and confirming the founder mutation in those with high levels by sequencing. Sequence the homogentisate 1,2-dioxygenase (HGD) gene to identify mutations and variants in 29 AKU non-gypsy cases. Results The founder mutation was detected in homozygous state in 41/499 AKU-affected individuals of the gypsy community giving a high prevalence of 8.4%. Low back pain, knee pain, and eye and ear pigmentation were the most common symptoms and signs respectively. The commonest mutation identified in the non-gypsy AKU cases was p.Ala122Val. Conclusion High prevalence of AKU in the inbred gypsy population at 8.4% was detected confirming the founder effect. Urine screening provided a cost-effective method to detect the disease early. Mutation spectrum is varied in the rest of the Indian population. This study identified maximum number of mutations in exon 6 of the HGD gene. Key Points • High prevalence (8.4%) of alkaptonuria (AKU) in the gypsy population due to founder mutation in the HGD gene. • Inbreeding exemplifies the founder effects of this rare genetic disorder. • Urinary screening is a cost-effective method in this community for early detection of AKU and intervention. • The mutation spectrum causing AKU is diverse in the rest of the Indian population.

Turner syndrome (TS) is a common multiple congenital anomaly syndrome resulting from complete or partial absence of the second X chromosome. In this study, we explore the phenotype of TS in diverse populations using clinical examination and facial analysis technology. Clinical data from 78 individuals and images from 108 individuals with TS from 19 different countries were analyzed. Individuals were grouped into categories of African descent (African), Asian, Latin American, Caucasian (European descent), and Middle Eastern. The most common phenotype features across all population groups were short stature (86%), cubitus valgus (76%), and low posterior hairline 70%. Two facial analysis technology experiments were conducted: TS versus general population and TS versus Noonan syndrome. Across all ethnicities, facial analysis was accurate in diagnosing TS from frontal facial images as measured by the area under the curve (AUC). An AUC of 0.903 (p < .001) was found for TS versus general population controls and 0.925 (p < .001) for TS versus individuals with Noonan syndrome. In summary, we present consistent clinical findings from global populations with TS and additionally demonstrate that facial analysis technology can accurately distinguish TS from the general population and Noonan syndrome.

Craniofrontonasal syndrome (CFNS) (OMIM #304110) is a very rare, X-linked developmental disorder characterized by facial stigmata, including hypertelorism, frontonasal dysplasia, craniosynostosis, bifid nasal tip, and digital abnormalities. CFNS is caused by mutations in the Ephrin 1 gene (EFNB1) located at Xq13.1, which encodes the transmembrane protein Ephrin B1. Interestingly, heterozygous females are more severely affected than hemizygous males. We report on four individuals from four unrelated Indian families with mild-to-severe CFNS. All patients had variable degrees of hypertelorism and nasal bridge depression, which did not correlate with changes in other tissues. Although patients 3 and 4 showed the most severe facial dysmorphism and syndactyly, there were no structural CNS changes or developmental delay. In contrast, patient 1 displayed agenesis of corpus callosum and developmental delay, although facial and finger abnormalities were milder. Patients 1, 2, and 4 showed different degrees of clefting. DNA sequencing revealed four previously undescribed heterozygous mutations in exons 1 and 2 of EFNB1. Patient 1 carried the second single amino acid deletion reported up to date. The other three affected individuals harbored frameshift mutations, leading to premature termination codons. Our findings broaden the spectrum of EFNB1 mutations and illustrate the absence of an obvious correlation between mutation type, severity, and expression of symptoms.

The risk for recurrence of non disjunction trisomy 21 is conventionally consideredto be less than 1%. Within a span of 3years, we observed recurrence of non disjunction trisomies infour families. The objective of the presentstudy was to determine low level mosaicism in either of the couple and to identify the parental origin of additional chromosome 21/18. The four couples who had recurrent trisomic conceptions were investigated for the underlying mosaicism by analysis of 100 cells from peripheral blood of the couple and the parental origin of supernumerary chromosome 21/18 were identified using microsatellite markers. Low level mosaicisms in peripheral lymphocytes of couple were ruled out for all four families. Microsatellite markers have shown maternal origin of chromosomal nondisjunction for all the families and defective first meiotic division as the most common mechanism for nondisjunction. This observation raises the need for discussing the option of invasive testing while counseling the couple with an affected child with non-disjunction trisomy as the risk for recurrence of trisomies in subsequent pregnancy might not be as low as 1%.

Osteogenesis imperfecta (OI) is a heritable connective tissue disorder, mainly characterized by bone fragility and low bone mass. Defects in the type I procollagen‐encoding genes account for the majority of OI, but increasingly more rare autosomal recessive (AR) forms are being identified, which are caused by defects in genes involved in collagen metabolism, bone mineralization, or osteoblast differentiation. Bi‐allelic mutations in WNT1 have been associated with a rare form of AR OI, characterized by severe osteoporosis, vertebral compression, scoliosis, fractures, short stature, and variable neurological problems. Heterozygous WNT1 mutations have been linked to autosomal dominant early‐onset osteoporosis. In this study, we describe the clinical and molecular findings in 10 new patients with AR WNT1‐related OI. Thorough revision of the clinical symptoms of these 10 novel patients and previously published AR WNT1 OI cases highlight ptosis as a unique hallmark in the diagnosis of this OI subtype.

Mucolipidosis-IIIγ (ML-IIIγ) is a recessively inherited slowly progressive skeletal dysplasia caused by mutations in GNPTG. We report the genetic and clinical findings in the largest cohort with ML-IIIγ so far: 18 affected individuals from 12 families including 12 patients from India, five from Turkey, and one from the USA. With consanguinity confirmed in eight of 12 families, molecular characterization showed that all affected patients had homozygous pathogenic GNPTG genotypes, underscoring the rarity of the disorder. Unlike ML-IIIαβ, which present with a broader spectrum of severity, the ML-III γ phenotype is milder, with onset in early school age, but nonetheless thus far considered phenotypically not differentiable from ML-IIIαβ. Evaluation of this cohort has yielded phenotypic findings including hypertrophy of the forearms and restricted supination as clues for ML-IIIγ, facilitating an earlier correct choice of genotype screening. Early identification of this disorder may help in offering a timely intervention for the relief of carpal tunnel syndrome, monitoring and surgery for cardiac valve involvement, and evaluation of the need for joint replacement. As this condition may be confused with rheumatoid arthritis, confirmation of diagnosis will prevent inappropriate use of immunosuppressants and disease-modifying agents.