Garg, Abhimanyu

Abstract Context Mandibular hypoplasia, deafness, progeroid features, and lipodystrophy (MDPL) syndrome is a rare, autosomal dominant disorder due to pathogenic heterozygous variants in POLD1. Clinical features of MDPL vary between patients; however, there is no previously reported genotype-phenotype association. Objective This work reports 14 new patients with lipodystrophy due to POLD1 variants and compares phenotypic differences between those with p.Ser605del and missense variants. Methods Genetic sequencing was performed on DNA of 14 patients for POLD1 variants, including exome (n = 10), genome (n = 1), and candidate gene (n = 3) sequencing. Comparisons of demographic, clinical features, and metabolic complications between carriers of POLD1 p.Ser605del and missense variants in our cases and those reported in the literature were made using the Fisher exact test for categorical variables and the t test for continuous variables. Results A total of 9 different POLD1 variants were identified in our patients, including 3 novel variants: p.Asp25Glufs*16, p.Arg507His, and p.Trp781Cys. Compared to individuals with missense variants (n = 15), those with the p.Ser605del (n = 26) POLD1 variant had significantly increased prevalence of mandibular hypoplasia (57% vs 100%, respectively; P = .015), small mouth (36% vs 100%, respectively; P = .015), crowded teeth (44% vs 91%, respectively; P = .046), and hypogonadism in male patients (0% vs 92%, respectively; P = .046). There were no differences in the prevalence of metabolic complications, such as diabetes, hypertriglyceridemia, and hepatic steatosis, in the two groups. Conclusion Individuals with the heterozygous POLD1 p.Ser605del variant had typical MDPL with more severe phenotype compared to those with missense variants with atypical MDPL.

AbstractMorbidity and mortality rates in patients with autosomal recessive, congenital generalized lipodystrophy type 4 (CGL4), an ultra‐rare disorder, remain unclear. We report on 30 females and 16 males from 10 countries with biallelic null variants in CAVIN1 gene (mean age, 12 years; range, 2 months to 41 years). Hypertriglyceridemia was seen in 79% (34/43), hepatic steatosis in 82% (27/33) but diabetes mellitus in only 21% (8/44). Myopathy with elevated serum creatine kinase levels (346–3325 IU/L) affected all of them (38/38). 39% had scoliosis (10/26) and 57% had atlantoaxial instability (8/14). Cardiac arrhythmias were detected in 57% (20/35) and 46% had ventricular tachycardia (16/35). Congenital pyloric stenosis was diagnosed in 39% (18/46), 9 had esophageal dysmotility and 19 had intestinal dysmotility. Four patients suffered from intestinal perforations. Seven patients died at mean age of 17 years (range: 2 months to 39 years). The cause of death in four patients was cardiac arrhythmia and sudden death, while others died of prematurity, gastrointestinal perforation, and infected foot ulcers leading to sepsis. Our study highlights high prevalence of myopathy, metabolic abnormalities, cardiac, and gastrointestinal problems in patients with CGL4. CGL4 patients are at high risk of early death mainly caused by cardiac arrhythmias.

AbstractBackgroundDiabetes mellitus (DM) in children and adolescents is typically caused by type 1 DM, followed by type 2 DM and maturity‐onset diabetes of the young (MODY). We report an unusual Asian Indian family in which three members presented with DM at ages 15, 20, and 30, but not fitting the typical clinical picture of type 1 DM, type 2 DM, or MODY. The primary objective was to elucidate the molecular genetic basis of DM in this family.MethodsThe proband, a 22‐year‐old man, had short stature, gray hair, osteoporosis, and markedly reduced subcutaneous fat on the body, especially on the extremities along with acanthosis nigricans, and developed myxoid malignant peripheral nerve sheath tumor. Detailed family history revealed multiple loops of consanguinity. The proband underwent whole‐genome sequencing, and seven relatives underwent whole‐exome sequencing.ResultsThe proband and three additional family members were found to have the homozygous c.561A>G nucleotide variant of WRN RecQ‐like helicase (WRN) gene consistent with the diagnosis of Werner's syndrome. The c.561A>G variant induces a new splicing site on exon 6 resulting in a truncated WRN protein, p.Lys187Trpfs*13.ConclusionOur report brings to attention the onset of DM during childhood or early adulthood in patients with Werner's syndrome who typically develop type 2 DM around the age of 30–40 years. Presence of consanguinity among parents, dysmorphic features, and malignancy should prompt consideration of diagnosis of Werner's syndrome.

Abstract Congenital generalized lipodystrophy (CGL) is a rare autosomal recessive disorder characterized by near complete absence of adipose tissue from birth. Recently, mutations in 1-acylglycerol-3-phosphate O-acyltransferase 2 (AGPAT2) and Berardinelli-Seip congenital lipodystrophy 2 (BSCL2) genes were reported in pedigrees linked to chromosomes 9q34 and 11q13, respectively. There are limited data regarding phenotypic differences between the various subtypes of CGL. Furthermore, whether there are additional loci for CGL remains unknown. Therefore, we genotyped 45 pedigrees with CGL for AGPAT2 and BSCL2 loci and compared the phenotypes in the various subtypes. Twenty-six pedigrees harbored mutations, including seven novel variants, in the AGPAT2 gene, and 11 pedigrees harbored mutations in the BSCL2 gene, including five novel variants. Eight pedigrees had no substantial alterations in either gene. Of these, three informative pedigrees showed no linkage to markers spanning the AGPAT2 and BSCL2 loci, and in six of the affected subjects, the transcripts of AGPAT2 and BSCL2 were normal. All subtypes of CGL showed high prevalence of diabetes, hypertriglyceridemia, and acanthosis nigricans. However, patients with BSCL2 mutations had lower serum leptin levels, an earlier onset of diabetes, and higher prevalence of mild mental retardation compared with other subtypes. We conclude that besides AGPAT2 and BSCL2, there may be additional loci for CGL. The genetic heterogeneity in CGL patients is accompanied by phenotypic heterogeneity.