Genetic study of eight Egyptian patients with pycnodysostosis: identification of novel CTSK mutations and founder effect.

This is the first Egyptian study with detailed clinical and orodental evaluation of eight patients with pycnodysostosis and identification of four mutations in CTSK gene with two novel ones and a founder effect. INTRODUCTION: Pycnodysostosis is a rare autosomal recessive skeletal dysplasia due to mutations in the CTSK gene encoding for cathepsin K, a lysosomal cysteine protease. METHODS: We report on the clinical, orodental, radiological, and molecular findings of eight patients, from seven unrelated Egyptian families with pycnodysostosis. RESULTS: All patients were offspring of consanguineous parents and presented with the typical clinical picture of the disorder including short stature, delayed closure of fontanels, hypoplastic premaxilla, obtuse mandibular angle, and drum stick terminal phalanges with dysplastic nails. Their radiological findings showed increased bone density, acro-osteolysis, and open cranial sutures. Mutational analysis of CTSK gene revealed four distinct homozygous missense mutations including two novel ones, c.164A>C (p. K55T) and c.433G>A (p.V145M). The c.164A>C (p. K55T) mutation was recurrent in three unrelated patients who also shared similar haplotype, suggesting a founder effect. CONCLUSION: Our findings expand the mutational spectrum of CTSK gene and emphasize the importance of full clinical examination of all body systems including thorough orodental evaluation in patients with pycnodysostosis.

Hypermanganesemia with dystonia, polycythemia and cirrhosis in 10 patients: Six novel SLC30A10 mutations and further phenotype delineation.

Biallelic mutations in the SLC30A10 gene cause an inborn error of Mn metabolism characterized by hypermanganesemia, polycythemia, early-onset dystonia, and liver cirrhosis (HMDPC). To date, only 14 families from various ethnic groups have been reported. Here, we describe 10 patients from 7 unrelated Egyptian families with HMDPC. Markedly elevated blood Mn levels, the characteristic basal ganglia hyperintensity on T1-weighted images, and variable degrees of extrapyramidal manifestations with or without liver disease were cardinal features in all patients. Eight patients presented with striking early diseased onset (≤2 years). Unexpectedly, early hepatic involvement before the neurological regression was noted in 3 patients. Mutational analysis of SLC30A10 gene revealed 6 novel homozygous mutations (c.77T > C (p.Leu26Pro), c.90C > G (p.Tyr30*), c.119A > C (p.Asp40Ala), c.122_124delCCT (p.Ser41del), c.780_782delCAT (p.Iso260del) and c.957 + 1G > C). Treatment using 2,3 dimercaptosuccinic acid as a manganese chelating agent showed satisfactory results with improvement of biochemical markers, hepatic manifestations and relative amelioration of the neurological symptoms. Our findings present a large cohort of patients with HMDPC from same ethnic group. The majority of our patients showed severe and early presentation with clear phenotypic variability among sibship. Moreover, we extend the phenotypic and mutational spectrum and emphasize the importance of early diagnosis and treatment of this potentially fatal disorder.

PGAP3-related hyperphosphatasia with mental retardation syndrome: Report of 10 new patients and a homozygous founder mutation.

BACKGROUND: Hyperphosphatasia with mental retardation syndrome (HPMRS) is caused by recessive mutations in genes involved in the glycosylphosphatidylinsitol pathway, including PGAP3. MATERIALS AND METHODS: We describe 10 patients from 8 Egyptian families presenting with developmental delay, severe intellectual disability, distinct facial dysmorphism and increased alkaline phosphatase. Sanger sequencing of PGAP3 was performed. RESULTS: Eight patients had cleft palate, 4 had postnatal microcephaly and 5 had seizures. Neuro-imaging findings showed thin corpus callosum in 9 patients, mild ventriculomegaly in 3 patients and variable degrees of cerebellar vermis hypoplasia in 4 patients, a finding not previously reported in patients with HPMRS. Additional manifestations included double row teeth, hypogenitalism and congenital heart disease. Biallelic loss of function mutations in the PGAP3 gene were detected in all patients. Nine patients were homozygous for the c.402dupC (p.M135Hfs*28) mutation strongly suggesting a founder effect. On the other hand, 1 patient had a novel mutation, c.817_820delGACT (p.D273Sfs*37). CONCLUSION: This is the largest series of patients with HPMRS from same ethnic group. Our results reinforce the distinct clinical and facial features of PGAP3-related HPMRS which are the clue for targeted genetic testing. Moreover, we present additional unreported clinical and neuro-imaging findings and a novel mutation thus expanding the phenotypic and mutational spectrum of this rare disorder.

CO-OCCURRENCE OF PRIMARY MICROCEPHALY CAUSED BY A NOVEL HOMOZYGOUS ASPM MUTATION ALONG WITH X-LINKED ICHTHYOSIS IN THE SAME PATIENT.

Autosomal recessive primary microcephaly is a heterogeneous genetic disorder caused by genes that affect neurogenesis. This form of microcephaly has not been associated with other congenital anomalies. ASPM mutations have been identified as the major cause implicated in autosomal recessive primary microcephaly. X-linked recessive ichthyosis, is an inborn error of steroid sulfatase metabolism characterized by dark and adhesive scaly skin. Here, we examined an Egyptian boy presenting with microcephaly and simplified gyral pattern. Additionally, he had ichthyosis that goes with the X-linked type. Mutation analyses of the ASPM gene for autosomal recessive primary microcephaly and STS gene of X-linked recessive ichthyosis were conducted revealing a co-occurrence of a novel homozygous splice site mutation of ASPM gene (c.2936+1G>A) and a partial deletion of STS spanning from exon 7-10. We propose that the phenotype of our patient results from the combined effects of mutations in both ASPM and STS that account for the neurological signs and skin manifestations, respectively. The association of isolated X-linked recessive ichthyosis and autosomal recessive primary microcephaly has never been reported in the literature. Careful clinical and genetic assessment of patients with atypical clinical phenotypes is crucial for detecting such rare double mutations and thus proper genetic counseling.

AMH gene mutations in two Egyptian families with persistent müllerian duct syndrome.

The anti-müllerian hormone (AMH) is responsible for regression of müllerian ducts during male sexual differentiation. Mutations in the AMH gene or its type II receptor gene AMHR2 lead to persistence of the uterus and fallopian tubes in male children, i.e. persistent müllerian duct syndrome (PMDS). Both conditions are transmitted according to an autosomal recessive pattern and are symptomatic only in males. We report on 2 unrelated Egyptian consanguineous families with PMDS. The first family comprised 3 affected prepubertal sibs complaining of undescended testes. Pelvic exploration and laparotomy revealed müllerian duct derivatives. The other family was presenting with an adolescent male with impalpable left testis, and pelvic exploration showed remnants of fallopian tubes and rudimentary uterus. AMH levels were very low and almost undetectable in all affected patients in both families. Direct sequencing of the coding region of the AMH gene identified 2 homozygous mutations in exon 1, R95X in the first family and V12G in the second family. These data confirmed the autosomal recessive type of PMDS. Molecular investigation of this rare disorder in a larger number of cases with undescended testes in Egypt is warranted for proper diagnosis and genetic counseling.

Zinc and copper status in children with bronchial asthma and atopic dermatitis.

The study comprised 40 children of both sexes aged from 2 to 12 years, 22 suffering from bronchial asthma and 18 suffering from atopic dermatitis. Twenty healthy children of comparable age and sex to the patients were studied as controls. All the children were subjected to full history including dietetic questionnaire, thorough examination, and to estimation of serum IgE, serum ceruloplasmin, and zinc and copper levels in both serum and hairs. The mean concentrations of zinc in serum and hairs were respectively 70.3 +/- 13.2 micrograms/100 ml and 167.5 +/- 23.0 micrograms/gm in asthmatic cases and 65.9 +/- 11.7 micrograms/100 ml and 164.8 +/- 23.6 micrograms/gm in those with atopic dermatitis. These levels were significantly (p less than 0.001) decreased in comparison to the control values (88.4 +/- 11.0 micrograms/100 ml and 194.5 +/- 18.6 micrograms/gm). On the other hand, a significant (p less than 0.001) increase in serum and hairs copper was demonstrated in both allergic groups compared to the controls. Mean copper values were respectively 79.5 +/- 8.06 micrograms/100 ml and 18.7 +/- 1.9 micrograms/gm in the asthmatic cases and 81.4 +/- 8.4 micrograms/100 ml and 17.8 +/- 2.08 micrograms/gm in cases with atopic dermatitis. The control mean concentrations were 67.95 +/- 6.37 micrograms/100 ml and 14.5 +/- 2.53 micrograms/gm respectively. Significant (p less than 0.001) higher levels of serum ceruloplasmin were observed in the allergic patients compared to the controls and were correlated with the hypercupremia. The results were discussed and a good dietetic intake of high biological value protein and zinc supplement was recommended to these patients in order to correct their disturbances especially the hypozincemia which could lead to exaggeration of their allergic conditions. The field of trace elements metabolism has grown rapidly over the past few years, particularly after the development of novel techniques as the atomic absorption spectrophotometry which had allowed the reliable measurements of several trace elements in tissues and so had opened a new field for many researches (Henkin, 1976). Zinc and copper are involved in cell and tissue growth. Zinc plays an important role in DNA and protein synthesis and is intimately involved with copper as cofactors in several important enzyme systems. The effects of many pathological conditions as congestive heart failure, pneumonia, rheumatic heart diseases, bronchitis, recurrent infection, hemolytic anemia, psoriasis, and malnutrition on the levels of serum zinc, copper, and other trace elements have been of interest to investigators for a number of years (Sinha and Gabrieli, 1970; David et al., 1984).(ABSTRACT TRUNCATED AT 400 WORDS)