Kenny-Caffey syndrome in six Bedouin sibships: Autosomal recessive inheritance is confirmed

Dental abnormalities in rare genetic bone diseases: Literature review

Currently, over 500 rare genetic bone disorders are identified. These diseases are often accompanied by dental abnormalities, which are sometimes the first clue for an early diagnosis. However, not many dentists are sufficiently familiar with phenotypic abnormalities and treatment approaches when they encounter patients with rare diseases. Such patients often need dental treatment but have difficulties in finding a dentist who can treat them appropriately. Herein we focus on major dental phenotypes and summarize their potential causes and mechanisms, if known. We discuss representative diseases, dental treatments, and their effect on the oral health of patients and on oral health-related quality of life. This review can serve as a starting point for dentists to contribute to early diagnosis and further investigate the best treatment options for patients with rare disorders, with the goal of optimizing treatment outcomes.

Clinical and Molecular Diagnosis of Osteocraniostenosis in Fetuses and Newborns: Prenatal Ultrasound, Clinical, Radiological and Pathological Features

Osteocraniostenosis (OCS, OMIM #602361) is a severe, usually lethal condition characterized by gracile bones with thin diaphyses, a cloverleaf-shaped skull and splenic hypo/aplasia. The condition is caused by heterozygous mutations in the FAM111A gene and is allelic to the non-lethal, dominant disorder Kenny‐Caffey syndrome (KCS, OMIM #127000). Here we report two new cases of OCS, including one with a detailed pathological examination. We review the main diagnostic signs of OCS both before and after birth based on our observations and on the literature. We then review the current knowledge on the mutational spectrum of FAM111A associated with either OCS or KCS, including three novel variants, both from one of the OCS fetuses described here, and from further cases diagnosed at our centers. This report refines the previous knowledge on OCS and expands the mutational spectrum that results in either OCS or KCS.

A case of severe TBCE-negative hypoparathyroidism-retardation-dysmorphism syndrome: Case report and literature review

Hypoparathyroidism-retardation-dysmorphism syndrome (HRD) is a rare autosomal recessive disorder attributed to the mutations in the tubulin-specific chaperone E (TBCE) gene, which is vital for microtubule function during mitosis, organelle positioning, and neuronal cytokinesis. HRD is a congenital syndromic hypoparathyroidism associated with growth deficiency, microcephaly, intellectual disability, ocular anomalies, and facial dysmorphism. To our knowledge, there is only one published case of mild HRD-like syndrome with no identifiable genetic etiology. We report a case of severe TBCE-negative phenotypic HRD in a 4-year-old female from India presenting with hypocalcemic seizures due to congenital hypoparathyroidism, extreme microcephaly, growth deficiency, ocular anomalies, and facial dysmorphism. SNP microarray and whole exome sequencing (WES) did not detect any abnormalities in TBCE or other genes of interest. WES revealed two variants of unknown clinical significance in CASC5 gene, which codes for a protein in the kinetochore and, interestingly similar to TBCE, is essential for proper microtubule function during mitosis and cell proliferation and has been implicated in primary microcephaly disorders. However, further targeted sequencing in the parents revealed both variants inherited from the unaffected mother. Significant copy number variant noise in the proband and her parents limited further analysis. At this time the role of variants in the CASC5 gene is unclear and cannot explain our patient's phenotype. In conclusion, we report a severe case of phenotypic HRD syndrome, in which extensive genetic evaluation failed to reveal an etiology. Our case demonstrates that the pathogenesis of HRD may be genetically heterogenous, meriting further genetic investigations.

Craniofacioskeletal syndrome: an X-linked dominant disorder with early lethality in males

A syndrome with multisystem manifestations has been observed in three generations of a Caucasian family. The findings in seven females provide a composite clinical picture of microcephaly, short stature, small retroverted ears, full tip of the nose overhanging the columella, short philtrum, thin upper lip, soft tissue excrescences at the angle of the mouth, small mandible, small hands and feet with brachydactyly, finger V clinodactyly, flat feet, an excessive number of fingerprint arches, and mild impairment of cognitive function. Two males were more severely affected and died in the initial months of life. They showed intrauterine growth retardation, broad cranium with wide sutures and fontanelles, cardiac defects, small hands and feet with abnormal digital creases and small nails, and genital abnormalities. The affected males had low serum calcium in the neonatal period. Serum calcium, phosphorous, and parathormone levels in the females were normal. Radiographs showed cortical thickening of the long bones, underdevelopment of the frontal sinuses, narrow pelvis and hypoplasia of the middle phalanx of finger five. MRI of the brain showed slightly reduced brain volumes and an extra gyrus of the superior temporal region. X-inactivation studies showed near complete skewing in two affected females, but were not informative in three others. X-linkage as the mode of inheritance is proposed on the basis of different severity in males/females, complete skewing of X-inactivation in informative females, and a lod score (1.5) suggestive of linkage to markers in Xq26-q27.

Hypoparathyroidism, retardation, and dysmorphism syndrome: impaired early growth and increased susceptibility to severe infections due to hyposplenism and impaired polymorphonuclear cell functions

Hypoparathyroidism, retardation, and dysmorphism (HRD) syndrome is the first reported disease caused by a defect in the tubulin folding and assembly pathway. We aimed to summarize our experience with a cohort of patients with HRD, analyze their growth, and evaluate patients' polymorphonuclear cell (PMN) functions. The records of 22 HRD patients in a single medical center were reviewed. Growth during infancy and early childhood were analyzed by the Infancy-Childhood-Puberty (ICP) growth model. PMN functions were compared with healthy controls. Twelve patients died and many hospitalizations due to infections and convulsions were recorded. Growth measurements, expressed as weight and height SD scores in boys at a mean age of 4 y were -13.1+/-3.8 and -8.7+/-1 and -16.6+/-4.4 and -9.5+/-2.4, respectively, in girls at a mean age of 6.4 y. Chemotactic migration, random migration, and phagocytosis of PMN from HRD patients were significantly lower than that of PMN from healthy controls. No significant differences were found in superoxide production of PMN from patients compared with controls. Functional hyposplenism has been demonstrated in most of the studied patients. The defect in the tubulin folding and assembly pathway, previously described in HRD, has grave consequences on growth and PMN functions.

Ophthalmic manifestations of Sanjad-Sakati syndrome

BACKGROUND

Sanjad-Sakati syndrome (SSS) is a rare disorder characterized by hypoparathyroidism, growth and developmental delay, and dysmorphism. The purpose of this report is to describe the ophthalmic manifestations of Sanjad-Sakati syndrome (SSS; hypoparathyroidism-mental retardation-dysmorphism syndrome, HRD) (OMIM 241410).

PATIENTS

We included a total of 17 patients who were seen at two hospitals in Riyadh.

METHODS

Each patient underwent a complete ophthalmologic evaluation including visual acuity assessment, orthoptic workup, slit-lamp biomicroscopy, intraocular pressure measurement, cycloplegic retinoscopy, funduscopy, corneal diameter, and axial length measurement.

RESULTS

All 17 (100%) of the patients had normal visual acuity. All patients had microphthalmia with normal intraocular pressure. Eight (47%) of the patients had esotropia and four (23%) had exotropia. Ophthalmoscopy revealed tortuous retinal blood vessels in all patients. Hyperopic astigmatism was present in 16 (94%) patients.

CONCLUSION

Patients with SSS display a variety of ocular findings including errors of refraction, strabismus, and retinal vascular tortuousity.

Parathyroid Development and the Role of Tubulin Chaperone E

The development of the parathyroid glands involves complex embryonic processes of cell-specific differentiation and migration of the glands from their sites of origin in the pharynx and pharyngeal pouches to their final positions along the ventral midline of the pharyngeal and upper thoracic region. The recognition of several distinct genetic forms of isolated and syndromic hypoparathyroidism led us to review the recent findings on the molecular mechanisms of the development of the parathyroid glands. Although far from being understood, a special emphasis was given to the possible role of tubulin chaperone E (TBCE), which was implicated in the pathogenesis of the hypopathyroidism, retardation and dysmorphism (HRD) syndrome. The novel finding that TBCE plays a critical role in the formation of the parathyroid opens a novel domain of research, not anticipated previously, into the complex process of parathyroid development.

Hypoparathyroidism-retardation-dysmorphism syndrome in a girl: A new variant not caused by aTBCEmutation-clinical report and review

Hypoparathyroidism-retardation-dysmorphism (HRD) or Sanjad-Sakati syndrome (SSS) (OMIM 241410) is a rare autosomal recessive (AR) inherited condition, characterized by congenital hypoparathyroidism (hypoPTH), retardation, seizures, and a typical facial dysmorphism, consisting of prominent forehead, deep-set eyes, and abnormal external ears. This disorder has been mapped to the long arm of chromosome 1 (1q42-q43) and mutations in the gene coding for tubulin-specific chaperone E (TBCE) have been identified as the cause of the disease. Mutations in the same gene were also reported in patients with AR Kenny-Caffey syndrome (KCS). We report on a 41/2-year-old girl with congenital hypoPTH, seizures, developmental delay, and a facial dysmorphism, compatible with HRD syndrome. Mutation analyses revealed no mutations in the TBCE gene. In addition, normal TBCE protein and alpha-tubulin immunostaining were observed in a lymphoblastoid line derived from the patient, excluding the TBCE gene as the causative gene of the syndrome in this patient. A de novo microduplication of probe RP11-262I1 on 4q35 in the proposita was detected by microarray analyses, but this could not be confirmed by additional studies. We review and discuss the clinical findings of our case and those of the other reported cases with SSS and AR KCS. We conclude that a second gene locus for this disorder seems probable and that 4q35 needs further evaluation as a candidate region.

Variant arabe du syndrome de Kenny : à propos d’une famille maghrébine

Kenny syndrome is rare. Clinical feature include severe dwarfism, growth retardation macrocephaly, episodic hypocalcemia, internal cortical thickening and medullary stenosis of tubular bones. Genetic and phenotypic polymorphisms are characteristic. We report the observation of a Tunisian girl with the arabic variant of Kenny syndrome. She had chronic hypoparathyroidism, classic dwarfism, short stature with hormone deficiency, mental retardation and low helper/suppressor ratio. Our patient had two sisters and one brother with the same dysmorphic face and a marked intra-uterine growth retardation. They died from severe infections. Hypoparathyroidism was established in one sister.

Hypoparathyroidism-retardation-dysmorphism (HRD) syndrome in triplets

We report female triplets with the clinical and biochemical manifestations of hypoparatyroidism-retardation-dysmorphism (HRD) syndrome also known as Sanjad-Sakati syndrome. They were born at 35 weeks gestation after assisted pregnancy (in vitro fertilization). The parents are first degree cousins from Saudi Arabia.

Hypoparathyroidism-retardation-Dysmorphism (HRD) syndrome--a review

Hypoparathyroidism, retardation, and dysmorphism (HRD) is a newly recognized genetic syndrome, described in patients of Arab origin. The syndrome consists of permanent congenital hypoparathyroidism, severe prenatal and postnatal growth retardation, and profound global developmental delay. The patients are susceptible to severe infections including life-threatening pneumococcal infections especially during infancy. The main dysmorphic features are microcephaly, deep-set eyes or microphthalmia, ear abnormalities, depressed nasal bridge, thin upper lip, hooked small nose, micrognathia, and small hands and feet. A single 12-bp deletion (del52-55) in the second coding exon of the tubulin cofactor E (TCFE) gene, located on the long arm of chromosome 1, is the cause of HRD among Arab patients. Early recognition and therapy of hypocalcemia is important as is daily antibiotic prophylaxis against pneumococcal infections.

Mutation of TBCE causes hypoparathyroidism-retardation-dysmorphism and autosomal recessive Kenny-Caffey syndrome

The syndrome of congenital hypoparathyroidism, mental retardation, facial dysmorphism and extreme growth failure (HRD or Sanjad-Sakati syndrome; OMIM 241410) is an autosomal recessive disorder reported almost exclusively in Middle Eastern populations. A similar syndrome with the additional features of osteosclerosis and recurrent bacterial infections has been classified as autosomal recessive Kenny-Caffey syndrome (AR-KCS; OMIM 244460). Both traits have previously been mapped to chromosome 1q43-44 (refs 5,6) and, despite the observed clinical variability, share an ancestral haplotype, suggesting a common founder mutation. We describe refinement of the critical region to an interval of roughly 230 kb and identification of deletion and truncation mutations of TBCE in affected individuals. The gene TBCE encodes one of several chaperone proteins required for the proper folding of alpha-tubulin subunits and the formation of alpha-beta-tubulin heterodimers. Analysis of diseased fibroblasts and lymphoblastoid cells showed lower microtubule density at the microtubule-organizing center (MTOC) and perturbed microtubule polarity in diseased cells. Immunofluorescence and ultrastructural studies showed disturbances in subcellular organelles that require microtubules for membrane trafficking, such as the Golgi and late endosomal compartments. These findings demonstrate that HRD and AR-KCS are chaperone diseases caused by a genetic defect in the tubulin assembly pathway, and establish a potential connection between tubulin physiology and the development of the parathyroid.

Molecular and radiological diagnosis of sclerosing bone dysplasias

Bone mineral density (BMD) is a quantitative trait for which the heritability of the variance is estimated to be up to 80%, based on epidemiological and twin studies. Further illustration of the involvement of genetic factors in bone homeostasis, is the existence of an extended group of genetic conditions associated with an abnormal bone density. The group of conditions with increased bone density has long been poorly studied and understood at the molecular genetic level but recently, thanks to recent developments in molecular genetics and genomics, for some of them major breakthroughs have been made. These findings will make the molecular analysis of such patients an additional tool in diagnostics and in genetic counseling. However, the initial identification of affected patients is still largely dependent upon recognition of clinical and radiological stigmata of the disease. Therefore, in this overview of sclerosing bone dysplasias, the classical clinical and radiological signs of this group of disorders will be discussed along with the new molecular insights.

Prenatal diagnosis of hypoparathyroidism retardation and dysmorphism (HRD) syndrome

We used linkage analysis for prenatal diagnosis of the recently reported hypoparathyroidism, retardation, and dysmorphism (HRD) syndrome. Five cases from four families were evaluated. Three fetuses were carriers and were born healthy. Two fetuses were affected but the parents decided not to terminate the pregnancies. The diagnosis of HRD syndrome was confirmed in these newborns. This is the first report about prenatal diagnosis of HRD syndrome.

Sanjad-Sakati and autosomal recessive Kenny-Caffey syndromes are allelic: evidence for an ancestral founder mutation and locus refinement

The Sanjad-Sakati syndrome (SSS; MIM241410), an autosomal recessive trait characterized by congenital hypoparathyroidism, growth and mental retardation, seizures, and a characteristic physiognomy, was recently linked to chromosome area 1q42-q43. SSS resembles the autosomal recessive form of Kenny-Caffey syndrome (KCS; MIM244460), with similar manifestations but lacking osteosclerosis. Since KCS was recently linked to the region 1q42-q43, the possibility that this disorder is allelic with SSS was considered. Eight Sanjad-Sakati families from Saudi Arabia were genotyped with polymorphic short tandem repeat markers from the SSS/KCS critical region. A maximum multipoint LOD score of 14.32 was obtained at marker D1S2649, confirming linkage of SSS to the same region as autosomal recessive KCS. Haplotype analysis refined the critical region to 2.6 cM and identified a rare haplotype present in all the SSS disease alleles, indicative of a common founder. In addition to the assignment of the Saudi SSS and Kuwaiti KCS syndromes to overlapping genetic intervals, comparison of the haplotypes unexpectedly demonstrated that the diseases shared an identical haplotype. This finding, combined with the clinical similarity between the two syndromes, suggests that the two conditions are not only allelic but are also caused by the same ancestral mutation.

Kenny-Caffey syndrome: an Arab variant?

We describe 2 unrelated Bedouin girls who met the criteria for the diagnosis of Kenny-Caffey syndrome. The girls had some unusual features--microcephaly and psychomotor retardation--that distinguish the Kenny-Caffey syndrome profile in Arab children from the classical Kenny-Caffey syndrome phenotype characterized by macrocephaly and normal intelligence. The 2 girls did not harbor the 22q11 microdeletion (the hallmark of the DiGeorge cluster of diseases) that we previously reported in another Bedouin family with the Kenny-Caffey syndrome (Sabry et al. J Med Genet 1998: 35(1): 31-36). This indicates considerable genetic heterogeneity for this syndrome. We also review previously reported 44 Arab/Bedouin patients with the same profile of hypoparathyroidism, short stature, seizures, mental retardation and microcephaly. Our results suggest that these patients represent an Arab variant of Kenny-Caffey syndrome with characteristic microcephaly and psychomotor retardation. We suggest that all patients with Kenny-Caffey syndrome should be investigated for the 22q11 microdeletion. Other possible genetic causes for the Kenny-Caffey syndrome or its Arab variant include chromosome 10p abnormalities.

The autosomal recessive Kenny-Caffey syndrome locus maps to chromosome 1q42-q43

Kenny-Caffey syndrome (KCS) is an osteosclerotic bone dysplasia with associated hypocalcemia and ocular abnormalities. Both autosomal dominant (MIM127000) and autosomal recessive (MIM244460) inheritance patterns have been described. Using eight consanguineous Kuwaiti kindreds, a genome-wide search for linkage to the gene causing the autosomal recessive form of KCS was performed with polymorphic short tandem repeat markers. Significant linkage to a locus situated at chromosome 1q42 --> q43 with a maximal two-point lod score of 13.30 with marker D1S2649 was obtained. Haplotype analysis of flanking markers identified recombination events defining the KCS locus to a region between markers D1S2800 on the centromeric boundary and D1S2850 on the telomeric boundary, an approximately 4-cM interval. All affected individuals in these unrelated kindreds were homozygous for identical alleles at markers D1S2649 and D1S235, suggesting a single ancestral mutation underlying the disease in these families. Haploinsufficiency at 22q11, reported in another consanguineous KCS kindred, was not documented in these families.

Kenny-Caffey syndrome and microorchidism

We report on two adolescent boys with Kenny-Caffey syndrome and microorchidism. The first patient had elevated levels of serum follicle-stimulating hormone, but normal levels of luteinizing hormone and testosterone. There was no evidence of a microdeletion of the Y chromosome. The second patient had Leydig cell hyperplasia with normal seminiferous tubules and spermatogenesis, and normal pituitary histologic findings at autopsy. The presence of microorchidism in these patients confirms the previous observations and suggests subfertility, but does not fully clarify the pathogenesis.

Homozygosity and linkage-disequilibrium mapping of the syndrome of congenital hypoparathyroidism, growth and mental retardation, and dysmorphism to a 1-cM interval on chromosome 1q42-43

The syndrome of hypoparathyroidism associated with growth retardation, developmental delay, and dysmorphism (HRD) is a newly described, autosomal recessive, congenital disorder with severe, often fatal consequences. Since the syndrome is very rare, with all parents of affected individuals being consanguineous, it is presumed to be caused by homozygous inheritance of a single recessive mutation from a common ancestor. To localize the HRD gene, we performed a genomewide screen using DNA pooling and homozygosity mapping for apparently unlinked kindreds. Analysis of a panel of 359 highly polymorphic markers revealed linkage to D1S235. The maximum LOD score obtained was 4.11 at a recombination fraction of 0. Analysis of three additional markers-GGAA6F06, D1S2678, and D1S179-in a 2-cM interval around D1S235 resulted in LOD scores >3. Analysis of additional chromosome 1 markers revealed evidence of genetic linkage disequilibrium and place the HRD locus within an approximately 1-cM interval defined by D1S1540 and D1S2678 on chromosome 1q42-43.

Kenny-Caffey syndrome is part of the CATCH 22 haploinsufficiency cluster

We report four sibs with Kenny-Caffey syndrome in a consanguineous Bedouin family. The first two died in the neonatal period while the remaining affected brother and sister had all the characteristic clinical, biochemical, and radiological abnormalities of the syndrome. These included severe pre- and postnatal growth retardation, cortical thickening of the tubular bones with medullary stenosis, eye abnormalities, facial dysmorphism, hypocalcaemia, and low levels of parathyroid hormone. The children also showed intracranial calcification, impaired neutrophil phagocytosis, increased proportion of B lymphocytes, reduced CD4 and CD8 subpopulations of T lymphocytes, and inhibited transformation in response to Candida antigen. Fluorescence in situ hybridisation (FISH) was applied to blood lymphocyte metaphase spreads from these two Bedouin sibs and their parents using probe D22S75 (Oncor), specific for the DiGeorge critical region on chromosome 22q11.2. The presence of 22q11.2 haploinsufficiency was identified in the affected sibs, which was transmitted from the phenotypically normal mother. The present report widens the spectrum of CATCH 22 microdeletion to accommodate Kenny-Caffey syndrome.