ABSTRACT
Permanent neonatal diabetes mellitus (PNDM) caused by homozygous mutations in the glucokinase gene (GCK) is rare and only eight homozygous GCK mutations have been reported so far. Heterozygous GCK mutations cause maturity-onset diabetes of the young (MODY). We report four patients with growth retardation from two separate families (with three siblings in one family and one patient in another family) presenting with persistent hyperglycaemia within the first two days of life. We found one homozygous non-sense mutation (Q98X) in GCK in three siblings from one family and a homozygous missense GCK mutation (G261R) in one patient from another family. Both mutations have been identified previously in GCK-MODY in the heterozygous state. However, this is the first study to report the homozygous forms of these mutations in PNDM. We report four novel cases of PNDM caused by homozygous GCK mutations, including a non-sense mutation in exon 3 (Q98X) and a missense mutation in exon 7 (G261R).
Subject(s)
Diabetes Mellitus, Type 1/genetics , Diabetes Mellitus, Type 2/genetics , Glucokinase/genetics , Infant, Newborn, Diseases/genetics , Codon, Nonsense , Female , Homozygote , Humans , Infant, Newborn , Male , Mutation, Missense , Pedigree , SiblingsABSTRACT
Homozygous loss-of-function mutations in the transcription factor LHX3 have been associated with hypopituitarism with structural anterior pituitary defects and cervical abnormalities with or without restricted neck rotation. We report two novel recessive mutations in LHX3 in four patients from two unrelated pedigrees. Clinical evaluation revealed that all four patients exhibit varying degrees of bilateral sensorineural hearing loss, which has not been previously reported in association with LHX3 mutations, in addition to hypopituitarism including adrenocorticotropic hormone deficiency and an unusual skin and skeletal phenotype in one family. Furthermore, re-evaluation of three patients previously described with LHX3 mutations showed they also exhibit varying degrees of bilateral sensorineural hearing loss. We have investigated a possible role for LHX3 in inner ear development in humans using in situ hybridization of human embryonic and fetal tissue. LHX3 is expressed in defined regions of the sensory epithelium of the developing inner ear in a pattern overlapping that of SOX2, which precedes the onset of LHX3 expression and is known to be required for inner ear and pituitary development in both mice and humans. Moreover, we show that SOX2 is capable of binding to and activating transcription of the LHX3 proximal promoter in vitro. This study therefore extends the phenotypic spectrum associated with LHX3 mutations to encompass variable sensorineural hearing loss and suggests a possible interaction between LHX3 and SOX2 likely to be important for development of both the inner ear and the anterior pituitary in human embryonic development.
Subject(s)
Hearing Loss, Sensorineural/genetics , Homeodomain Proteins/genetics , Hypopituitarism/genetics , Mutation , Adolescent , Animals , Base Sequence , CHO Cells , Child , Cricetinae , Cricetulus , DNA-Binding Proteins/genetics , DNA-Binding Proteins/metabolism , Ear, Inner/embryology , Ear, Inner/growth & development , Ear, Inner/metabolism , Embryo, Mammalian/metabolism , Female , Gene Expression , HMGB Proteins/genetics , HMGB Proteins/metabolism , Hearing Loss, Sensorineural/embryology , Hearing Loss, Sensorineural/metabolism , Homeodomain Proteins/metabolism , Humans , Hypopituitarism/embryology , Hypopituitarism/metabolism , Infant , LIM-Homeodomain Proteins , Male , Mice , Polymorphism, Single Nucleotide , SOXB1 Transcription Factors , Transcription Factors/genetics , Transcription Factors/metabolism , Transcriptional ActivationABSTRACT
OBJECTIVES: This study aimed to describe the epidemiology of diabetes mellitus over the past two decades in Oman, particularly in terms of its prevalence and incidence. In addition, the study sought to estimate the future incidence of diabetes in Oman. METHODS: Three national and three regional surveys conducted between 1991 and 2010 were analysed to obtain the age-adjusted prevalence and undiagnosed proportion of type 2 diabetes mellitus (T2DM) among Omani subjects aged ≥20 years. Diabetes mellitus registers and published studies were used to determine incidence rates of both type 1 diabetes mellitus (T1DM) and T2DM in Oman. Linear regression was used to determine trends and projections for diabetes in 2050. RESULTS: The age-adjusted prevalence of T2DM in Oman varied from 10.4% to 21.1%, while the highest prevalence of impaired fasting glucose was found in males (35.1%). In comparison to men, higher incidence rates of T2DM were found in women (2.7 cases compared to 2.3 cases per 1,000 person-years, respectively). No significant trends were observed for the prevalence or incidence of T2DM in both genders. Undiagnosed T2DM was more common in men (range: 33-68%) than women (range: 27-53%). The results of this study show that by 2050, there will be an estimated 350,000 people with T2DM living in Oman (a 174% increase compared to estimates for 2015). CONCLUSION: Health authorities need to prioritise diabetes prevention and control in order to prevent or delay long-term complications and avert a potential epidemic of diabetes in Oman.