SPRED2 loss-of-function causes a recessive Noonan syndrome-like phenotype.

Upregulated signal flow through RAS and the mitogen-associated protein kinase (MAPK) cascade is the unifying mechanistic theme of the RASopathies, a family of disorders affecting development and growth. Pathogenic variants in more than 20 genes have been causally linked to RASopathies, the majority having a dominant role in promoting enhanced signaling. Here, we report that SPRED2 loss of function is causally linked to a recessive phenotype evocative of Noonan syndrome. Homozygosity for three different variants-c.187C>T (p.Arg63∗), c.299T>C (p.Leu100Pro), and c.1142_1143delTT (p.Leu381Hisfs∗95)-were identified in four subjects from three families. All variants severely affected protein stability, causing accelerated degradation, and variably perturbed SPRED2 functional behavior. When overexpressed in cells, all variants were unable to negatively modulate EGF-promoted RAF1, MEK, and ERK phosphorylation, and time-course experiments in primary fibroblasts (p.Leu100Pro and p.Leu381Hisfs∗95) documented an increased and prolonged activation of the MAPK cascade in response to EGF stimulation. Morpholino-mediated knockdown of spred2a and spred2b in zebrafish induced defects in convergence and extension cell movements indicating upregulated RAS-MAPK signaling, which were rescued by expressing wild-type SPRED2 but not the SPRED2Leu381Hisfs∗95 protein. The clinical phenotype of the four affected individuals included developmental delay, intellectual disability, cardiac defects, short stature, skeletal anomalies, and a typical facial gestalt as major features, without the occurrence of the distinctive skin signs characterizing Legius syndrome. These features, in part, characterize the phenotype of Spred2-/- mice. Our findings identify the second recessive form of Noonan syndrome and document pleiotropic consequences of SPRED2 loss of function in development.

Turner syndrome: results of the first Tunisian study group on Turner syndrome (TuSGOT).

OBJECTIVES: Early diagnosis in Turner syndrome is desirable to optimize growth and puberty and yet, it is often made late. Here, we aim to identify age at diagnosis, clinical features at presentation and potential strategies to improve the care of TS girls. METHODS: Retrospective study, including patients from 14 care centers across Tunisia including neonatal and pediatric care units, adult endocrinology and genetics departments. RESULTS: We identified 175 patients with TS, karyotype showing 45, xmonosomy in 83(47.4 %) with mosaicism in 37(20 %). Mean ± SD, median (range) age at diagnosis available in 173 patients was 13 ± 9.2,12 (birth-48) years. The diagnosis was antenatal in 4(2.3 %), from birth-2 years in 14 (8 %)with lymphoedema (8)and dysmorphic features (9),2-12 years in 53 (35.5 %) including 35 with short stature, 13-18 years in 43(28.8 %) with short stature(28) and delayed puberty(14) and 35(23.5 %) after 18 years, related to ovarian insufficiency (20) and short stature (11). The associated malformations were cardiac in 14 (12.8 %), renal in 22 (19.6 %). A total of 56 girls (32 %) had proven gonadal dysgenesis and 13 (7 %) had otological problems. Parental height was available in 71 girls (40 %) of whom 59 were below the lower end of parental target range (LTR) (83 %). CONCLUSIONS: This first Tunisian multicenter study, the first African of its kind, reveals that more than half of Turner syndrome cases are diagnosed after the age of 12 years. Subsequently, national strategies for an earlier TS diagnosis are needed such as measuring and plotting parental heights as well as introducing a systematic height screening at 5 years in Tunisia with a view to carrying out a re-audit in five years' time.

C677t polymorphism of MTHFR and G80A polymorphism of RFC genes and their relation with homocysteine levels in obese Tunisian children.

AIMS: To investigate the frequencies of C677T polymorphism in MTHFR gene and G80A polymorphism in RFC gene in obese and no obese Tunisian children and to assess their relation with homocysteine (tHcy), folate and vitamin B12 levels. METHODS: We have studied 31 obese compared to 22 no obese children. tHcy was assessed by fluorescence-immunoassay ; folate and vitamin B12 by radioimmunoassay. C677T and G80A mutations were detected using pyrosequencing. RESULTS: There were no differences in tHcy levels between obese and no obese, (10,34 ± 4,86µmoll/l vs11,00 ± 4,26µmoll/l). We found no difference for the allelic frequencies of the C677T polymorphism (29.03 % vs 30.95 %) and of the G80A polymorphism (64.52 % vs 59.52 %). Mean levels of tHcy, folic acid and vitamin B12 were not significantly different according to MTHFR and RFC genotypes. CONCLUSION: We demonstrated no difference in tHcy, folates, vitamin B12 levels and allelic frequencies of C677T and G80A polymorphisms in MTHFR and RFC genes between obese and no obese Tunisian children. These two polymorphisms don't seem to have any impact on homocysteine, folate and vitamin B12 status in the two populations.

A rare cause of cyanosis: Congenital methemoglobinemia.

Congenital Methemoglobinemia is a rare condition that may mimic congenital heart diseases. There are two types of congenital Methemoglobinemia. The type I is usually benign. The enzyme deficiency is limited to red blood cells. Clinically, the patient presents cyanosis without neurological disorders. Whereas, in type II, cyanosis is associated with severe neurological impairment.

Characteristics and etiologies of short stature in children: Experience of an endocrine clinic in a Tunisian tertiary care hospital.

BACKGROUND: Short stature is a common reason for referral to pediatric endocrinology clinics. It may be a manifestation of a pathological condition requiring early treatment. The aim of this study was to describe the characteristics and etiologies of short stature among children referred to the pediatric endocrinology clinic of the main pediatric tertiary care center in Tunisia. METHODS: Retrospective and descriptive study in the endocrinology unit of children referred for short stature between January 2012 and December 2016. Data on the patients' medical history, physical findings, laboratory tests, bone age and chromosomal analysis were collected. RESULTS: 470 children (266 males and 204 females) were referred during that period. 214 (45.5%) had normal height, and 80.8% of them were referred by general practitioners. The other 256 children (54.5%) had a confirmed short stature (mean age :7.2 years, mean height: -2.77 SDS). Endocrinological causes were the most common(43% GHD, 4% hypothyroidism) followed by intrauterine growth retardation IUGR (24%), genetic syndromes (8.4%), chronic pediatric diseases (7.8%), skeletal dysplasia (6.2%), normal variant of short stature (5%), and psychosocial deprivation (1.2%). Among non-endocrine causes, Turner syndrome was the most common genetic syndrome (4.4%), achondroplasia the main skeletal dysplasia (4%) and celiac disease the main chronic disease (3.4%). CONCLUSIONS: ST is largely overestimated in our country. Therefore, it is important to insist on adequate measurement and analysis of growth parameters to avoid unnecessary investigations. GHD and IUGR were the most common causes. Celiac disease, though frequent in Tunisia, is not a common cause of short stature.

Congenital hypothyroidism presenting with reversible renal impairment: an under-recognised problem?

BACKGROUND: Hypothyroidism with impairment of renal function and raised creatinine phosphokinase (CPK) is described in adults and children with acquired hypothyroidism, but not in congenital hypothyroidism. CASE PRESENTATION: A male infant born at term weighing 3390 g was seen aged 2 months with prolonged jaundice. Examination showed somnolence, umbilical hernia, enlarged fontanelles and lower limb edema; length 55 cm (-1.5 SD), weight 5.4 kg (-0.13 SD). Biochemistry showed fT4 < 1 pmol/L, TSH = 1044.36 µUI/mL, creatinine 77 µmol/L(normal <35 µmol/L), estimated glomerular filtration rate (GFR) 26 ml/min/1.73 m2, CPK 3952.5 IU/L (normal<400 IU/L). Ultrasound showed no thyroid tissue in the neck. In view of the renal impairment, peritoneal dialysis was initially contemplated but postponed and the child received levothyroxine 10 µg/kg/day. Two months later thyroid function tests, CPK and renal function had all normalized with creatinine 19 µmol/L and GFR 116 ml/min/1.73m2. DISCUSSION: Reversible renal impairment is attributable to severe congenital hypothyroidism causing decreased myocardial contractility and cardiac output and to a direct effect on the kidneys. Thyroid function should be checked in infants with renal impairment of unknown cause. Cautious fluid management is indicated in hypothyroid infants. Hypothyroidism may also be associated with elevated serum CPK levels but resolves with thyroxin therapy.

Validation of the Arabic and Tunisian Arabic version of the KINDL questionnaires for children with diabetes type 1.

AIM: We aimed to validate the Arabic and Tunisian Arabic versions of diabetes- specific quality of life (QOL) instrument KINDL-R Diabetes Module for Tunisian children population with type 1 diabetes. PATIENTS AND METHODS: This a cross-sectional study to validate Arabic and Tunisian KINDL QOL instrument that we translate in literary and dialectal Arabic. Both forward and backward translations from the German version of KINDL QOL into Arabic version were performed. Our project received a GPED grant in August 2014. After the face validity of the Arabic version was established, it was then pilot-tested. Finally, the validity and reliability of the final version of the Arabic KINDL questionnaire were evaluated. RESULTS: The KINDL-R Diabetes Module (DM) questionnaire of QOL was given to 212 persons : 108 children (aged 3-17 years) with T1DM and 104 parents. The Cronbach's alpha coefficients of the overall items and the main domains was about 0.7. The mean total score of the KINDL-R DM was 69,56  ± 14,01 in children aged 7-13 years, 59.93± 15.17 in children aged 13-17 years and 56.6± 9.9 in parents (higher scores indicate better QOL). The parents reported lower diabetes-specific HRQOL than the children themselves (p < 0.01).Emotional score was correlated to environment (p = 0,03). Self-esteem was reported to environment (p = 0,02) and mother's instruction level's (p = 0,014). CONCLUSIONS: The KINDL-R Diabetes Module (DM) of QOL in literary and dialectal Arabic have sufficient acceptability, reliability and validity so as to be used for the purposes of a comparative in Tunisian and Arabic populations.

Congenital lobar emphysema. Report of 17 cases.

UNLABELLED: The aim of this report is to determine frequency and clinical characteristics of Congenital lobar emphysema (CLE) at Children's Hospital of Tunis. METHODS: Cases of CLE managed between January the 1st 1994 until December the 31st 2004 were reviewed. RESULTS: Amongst 31 cases of cystic pulmonary malformations we report 17 CLE. They were 12 males and 5 females. The mean age at diagnosis was 41/2 months (20 days, 22 months). Symptoms were: progressive respiratory distress (n=11) recurrent attacks of dyspnea (n=5); pulmonary infection (n=1). Chest X ray and CT scans showed hyper aeration of the affected lobes. Three patients had two affected lobes. CLE was associated to bronchogenic cyst (n=2) and to congenital cardiac anomalies (n=3). All patients underwent lobectomy. Post operative course was uneventful in 16 children. CONCLUSION: CLE is an uncommon cause of respiratory distress in neonates and infants. CLE is the most common cystic pulmonary malformation in our institution.

Implementation of effective transition from pediatric to adult diabetes care: epidemiological and clinical characteristics-a pioneering experience in North Africa.

AIMS: Type 1 diabetes is increasing in children leading more T1D young adults to adult healthcare settings. This change is experienced as a tear and results in a disengagement from specialist services. This study reports on an implementation of an effective and pioneering program of transition in North Africa. METHODS: A total of 65 teenagers with T1D were recruited for a structured program of transition. They attend transitional meetings involving both pediatric and adult team and were, when ready, welcomed in specialized consultations for adolescents with a special « passport ¼. Here we study their characteristics before and after structured transition and the benefit of this program. RESULTS: 9 transition meetings took place (September 2012-December 2017). Mean age was 16.5 years. Mean age at onset of T1D was 7.5 years with average pediatric follow-up of 9 years.72% of young adults felt satisfied. After the transition meeting, 74% of patients wished to join directly adult unit. They were followed there for 28.4 ± 16.2 months. The glycaemic control improved significantly with a decrease in HbA1C of 0.93 ± 1.69% the first year of follow-up and the number of young adults achieving a HbA1C < 7.5% increased by 8%. CONCLUSION: This program was beneficial for 75% of patients who demonstrated an improvement in their metabolic control the year following transition to adult care service. To our knowledge, this study is the first one in North Africa to report on the outcome of a structured transition program from pediatric to adult diabetes care.

A founder mutation underlies a severe form of phosphoglutamase 3 (PGM3) deficiency in Tunisian patients.

Phosphoglucomutase 3 (PGM3) protein catalyzes the conversion of N-acetyl-d-glucosamine-6-phosphate (GlcNAc-6-P) to N-acetyl-d-glucosamine-1-phosphate (GlcNAc-1-P), which is required for the synthesis of uridine diphosphate N-acetylglucosamine (UDP-GlcNAc) an important precursor for protein glycosylation. Mutations in PGM3 gene have been recently shown to underlie a new congenital disorder of glycosylation often associated to elevated IgE. Herein, we report twelve PGM3 deficient patients. They belong to three highly consanguineous families, originating from a rural district in the west central Tunisia. The patient's clinical phenotype is characterized by severe respiratory and cutaneous infections as well as developmental delay and severe mental retardation. Fourteen patients died in early infancy before diagnosis supporting the severity of the clinical phenotype. Laboratory findings revealed elevated IgE, CD4 lymphopenia and impaired T cell proliferation in most patients. Genetic analysis showed the presence, of a unique homozygous mutation (p.Glu340del) in PGM3 gene leading to reduced PGM3 abundance. Segregating analysis using fifteen polymorphic markers overlapping PGM3 gene showed that all patients inherited a common homozygous haplotype encompassing 10-Mb on chromosome 6. The founder mutational event was estimated to have occurred approximately 100 years ago. To date, (p.Glu340del) mutation represents the first founder mutation identified in PGM3 gene. These findings will facilitate the development of preventive approaches through genetic counselling and prenatal diagnosis in the affected families.

Clinical and Genetic Characterization of 26 Tunisian Patients with Allgrove Syndrome.

BACKGROUND AND AIMS: Allgrove syndrome is characterized by achalasia, alacrima, and adrenal insufficiency as well as being associated with progressive neurological signs. This is an autosomal recessive disorder due to mutations in the AAAS gene located on chromosome 12q13. The AAAS gene encodes a protein of 546 amino acids, ALADIN. Mutations in this genwere reported in families from North Africa and Europe. Our objective is to conduct a clinical, molecular and genetic study of 26 Tunisian patients with Allgrove syndrome. METHODS: We report 26 Tunisian patients with between two and four clinical features associated with Allgrove syndrome. Blood samples were collected and isolated DNA derived from subjects was amplified. The entire sequence of the AAAS gene was analyzed by PCR and sequencing. PCR-RFLP method was performed to identify the frequent mutations found. RESULTS: Sequencing of the AAAS gene revealed a major homozygous mutation (c.1331+1G>A) in 25 patients and R286X mutation in one patient. The presence of a major mutation in several unrelated affected individuals suggests the presence of a founder effect in Tunisia and allows for a fast and targeted molecular diagnosis. CONCLUSIONS: We created an easy and rapid molecular enzymatic protocol based on PCR-RFLP using MvaI restriction enzyme that directly targets this major mutation and can be used for prenatal diagnosis and genetic counseling for Tunisian families at risk. To the best of our knowledge, this is the first major series report of Allgrove syndrome in Tunisia.