Molecular screening of a large cohort of Moroccan patients with congenital hypopituitarism.

BACKGROUND/OBJECTIVES: Congenital hypopituitarism is a rare disease which, for most patients, has no identified molecular cause. We aimed to document the molecular basis of growth retardation in a Moroccan cohort. DESIGN/PATIENTS: 80 index cases [54 with isolated growth hormone deficiency (IGHD), 26 with combined pituitary hormone deficiency (CPHD)] were screened for molecular defects in GH1 (including LCR-GH1), GHRHR, GHSR, GHRH, PROP1, POU1F1, HESX1, LHX3, LHX4 and SOX3. RESULTS: Five different deleterious mutations were identified in 14 patients from eight families. In the IGHD group, three genes were found to be involved: GH1, GHRHR and GHSR. In the CPHD group, PROP1 was the only mutated gene. In addition, two heterozygous variations whose deleterious effect remains to be demonstrated were identified (in GH1 and LHX4), and two polymorphisms (missense variations) were detected (in LHX3 and in GHSR). The prevalence of mutations in this Moroccan GHD cohort was 10% (8/80), 11·1% (6/54) in the IGHD group and 7·7% (2/26) in the CPHD group. CONCLUSION: This is the first molecular screening of congenital GHD in a Moroccan population and, like other studies, mutations were preferentially identified in familial cases (75%); mutations in genes such as POU1F1, HESX1, SOX3, LHX3 and LHX4 are extremely rare. The p.R73C PROP1 mutation was the most frequent mutation in CPHD; this should be the first one to screen in this population. Our results should contribute to a better diagnosis and management of this heterogeneous disease condition.

Screening of CYP1B1 and MYOC in Moroccan families with primary congenital glaucoma: three novel mutations in CYP1B1.

PURPOSE: To investigate the contribution of cytochrome P4501B1 (CYP1B1) and myocillin (MYOC) mutations to primary congenital glaucoma (PCG) in Moroccan families. METHODS: This study included 90 unrelated families with PCG and 100 normal control individuals. Two previously reported CYP1B1 mutations (g.4339delG and p.G61E) were first screened by polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP). The coding exons of CYP1B1 were sequenced in g.4339delG- and p.G61E-negative or heterozygous probands. Then the coding exons of MYOC were sequenced in patients who had no mutation in CYP1B1 or carried heterozygous CYP1B1 mutation. RESULTS: Twelve CYP1B1 mutations were identified in 43 PCG pedigrees. Three of them were novel (p.R163C, p.C470Y, and g.4330-4331delTG) and associated with moderate to severe phenotypes. Two novel intronic polymorphisms in CYP1B1 were identified in addition to those previously described. The g.4339delG was the most frequent mutation detected in 31 families (34.44%), followed by the p.G61E in seven families (7.77%). The remaining mutations (p.R163C, p.E173K, g.4330-4331delTG, p.E229K, p.R390S, p.R368H, p.R469W, p.C470Y, and g.7901-7913del13bp) were infrequent. One family with the p.R390S mutation showed both PCG and primary open angle glaucoma (POAG) phenotypes. One proband was heterozygous for p.T193K mutation in MYOC. This mutation has been initially associated with POAG, but never with PCG. CONCLUSIONS: Our results support that mutations in CYP1B1 are a major cause for PCG in the Moroccan population with a predominance of the g.4339delG mutation. Furthermore, these results demonstrate the diversity of CYP1B1 mutations, while suggesting a modest role of MYOC in Moroccan PCG.

Loss of constitutive activity of the growth hormone secretagogue receptor in familial short stature.

The growth hormone (GH) secretagogue receptor (GHSR) was cloned as the target of a family of synthetic molecules endowed with GH release properties. As shown recently through in vitro means, this receptor displays a constitutive activity whose clinical relevance is unknown. Although pharmacological studies have demonstrated that its endogenous ligand--ghrelin--stimulates, through the GHSR, GH secretion and appetite, the physiological importance of the GHSR-dependent pathways remains an open question that gives rise to much controversy. We report the identification of a GHSR missense mutation that segregates with short stature within 2 unrelated families. This mutation, which results in decreased cell-surface expression of the receptor, selectively impairs the constitutive activity of the GHSR, while preserving its ability to respond to ghrelin. This first description, to our knowledge, of a functionally significant GHSR mutation, which unveils the critical importance of the GHSR-associated constitutive activity, discloses an unusual pathogenic mechanism of growth failure in humans.

Cytogenetic Profile of Moroccan Pediatric Acute Lymphoblastic Leukemia: Analysis of 155 Cases With a Review of the Literature.

BACKGROUND: Acute lymphoblastic leukemia (ALL) is the most common malignancy in children, with a peak incidence at 2 to 3 years of age and accounting for almost 30% of all cancers in this age group. It is well established that the identification of cytogenetic abnormalities is highly relevant for the prognosis of and therapeutic decisions in ALL. The purpose of the present study was to define the frequency of recurrent chromosomal abnormalities of ALL in Moroccan patients referred exclusively to the BIOLAB Laboratory of the Children's Hospital of Rabat during a 4-year period and compare our findings to the reported data. PATIENTS AND METHODS: We performed conventional karyotyping of 155 ALL cases, with a successful cell culture rate of 94%. RESULTS: We identified chromosomal abnormalities in 66% of the total studied cases, of which 70% revealed important recurrent abnormalities with high prognostic value, such as hyperdiploidy, hypodiploidy, t(9;22), t(8;14), t(1;19), and MLL rearrangements. In total agreement with the reported data, most of the patients (56%) in the present study were aged 1 to 5 years, with a male predominance, and B-ALL was the most common blast phenotype (85%). CONCLUSION: The frequency of most chromosomal rearrangements successfully identified in our study and their lineage correlated with those reported in the published data.

Genotype-phenotype correlation in Moroccan patients with primary congenital glaucoma.

PURPOSE: To investigate the genotype-phenotype correlation in a large cohort of Moroccan primary congenital glaucoma (PCG) in which CYP1B1 mutation spectrum was recently reported by our group. METHODS: This study included 94 patients from 84 unrelated Moroccan PCG families with or without CYP1B1 mutations. Clinical features, severity of the phenotype, and prognosis were mainly compared in patients with no CYP1B1 mutations, double CYP1B1 null alleles or nondouble null but other CYP1B1 mutations; most of them were hypomorphic mutations. Statistical analyses were performed using SAS and SPSS softwares. Significance was set at P<0.05. RESULTS: Mean of intraocular pressure, corneal diameter and number of surgery values and cup-to-disc ratios, and percentages of patients with bilateral PCG, eyes with severe opacities and severe phenotype, and those that needed >1 trabeculectomy were significantly higher in the CYP1B1 mutation carriers (n=51) than in the no CYP1B1 mutation group (n=43). The same results were observed when patients with double CYP1B1 null alleles (n=34) were compared with those with no CYP1B1 mutation. The comparison between the no CYP1B1 mutation patients and those with nondouble null but other CYP1B1 mutations (n=17) showed significant differences in the percentage of bilateral PCG and percentages of eyes with severe opacities and severe phenotype. When the double CYP1B1 null allele carriers were compared with the nondouble null but other CYP1B1 mutation group, only significant differences were observed in the mean number of surgery values. Multivariate analysis revealed that, after adjustment of the parameters that showed significant differences in univariate analyses, corneal diameter was the main factor explaining the severity of PCG only in the double CYP1B1 null allele carriers. CONCLUSIONS: This is the first report of genotype-phenotype correlation in a large cohort of Moroccan PCG. Our results revealed that the worst phenotype and prognosis were observed in the double null CYP1B1 allele carriers followed by the nondouble null but other CYP1B1 mutations. This will contribute to the prediction of the prognosis of the disease.

Evidence of clinical and genetic heterogeneity in autosomal dominant congenital cerulean cataracts.

Autosomal dominant cerulean cataracts (ADCC) have previously been mapped to two loci: one on chromosome 17q24 and the other on chromosome 22q11.2-q12.2, which includes the beta-B2 crystallin (CRYBB2) candidate gene. Using polymorphic markers in these regions (D17S802, D17S836, D17S1806 and CRYBB2, D22S258) for linkage analysis, we excluded these loci in a large Moroccan family presenting with an unusual form of ADCC with early onset of lens opacities and rapid evolution. This finding confirms the clinical and genetic heterogeneity of autosomal dominant congenital cerulean cataracts.

[C634R mutation of the protooncongene RET and molecular diagnosis in multiple endocrine neoplasia type 2 in a large Moroccan family]. / Mutation C634R du proto-oncogène RET et diagnostic moléculaire dans une grande famille marocaine de néoplasie endocrinienne multiple de type 2A.

Multiple endocrine neoplasia (MEN) 2A is an inherited disease characterized by the development of medullary thyroid carcinoma (MTC), pheochromocytoma and/or hyperparathyroïdism. It has been shown to be associated with germline mutations in the RET proto-oncogene. Direct DNA testing, therefore allows the identification of subjects with asymptomatic MEN 2A who can be offered prophylactic thyroidectomy and biochemical screening as preventive measures. DNA analysis of RET exon 8, 10, 13, 14, 15 and 16 was performed by direct sequencing of PCR product on automated sequencer and or PCR-digestion. In this report, we describe a MEN2A family witch initially seemed a sporadic case of MTC. We first characterized the C634R RET mutation in the index and then we identified 3 carriers who developed the disease and 3 young carriers who were apparently asymptomatic. A genetic counselling and the management of the carriers were proposed. This study confirmed that genetic testing ; in order to detect gene carriers is technically possible in Morocco. This will contribute to the definition of a national policy of this cancer control.

Unusual phenotypic features in a patient with a novel splice mutation in the GHRHR gene.

Isolated growth hormone deficiency (IGHD) may be of genetic origin. One of the few genes involved in that condition encodes the growth hormone releasing hormone receptor (GHRHR) that, through its ligand (GHRH), plays a pivotal role in the GH synthesis and secretion by the pituitary. Our objective is to describe the phenotype of two siblings born to a consanguineous union presenting with short stature (IGHD) and Magnetic Resonance Imaging (MRI) abnormalities, and to identify the molecular basis of this condition. Our main outcome measures were clinical and endocrinological investigations, MRI of the pituitary region, study of the GHRHR gene sequence and transcripts. In both patients, the severe growth retardation (-5SD) was combined with anterior pituitary hypoplasia. In addition to these classical phenotypic features for IGHD, one of the patients had a Chiari I malformation, an arachnoid cyst, and a dysmorphic anterior pituitary. A homozygous sequence variation in the consensus donor splice site of intron 1 (IVS1 + 2T > G) of the GHRHR gene was identified in both patients. Using in vitro transcription assay, we showed that this mutation results in abnormal splicing of GHRHR transcripts. In this report, which broadens the phenotype associated with GHRHR defects, we discuss the possible role of the GHRHR in the proper development of extrapituitary structures, through a mechanism that could be direct or secondary to severe GH deficiency.