Clinical and genetic analysis of a newborn with hypoparathyroidism, sensorineural hearing loss, and renal dysplasia syndrome / 中华医学遗传学杂志

OBJECTIVE@#To analyze the clinical phenotype and genetic basis for a male neonate featuring hypoparathyroidism, sensorineural hearing loss, and renal dysplasia (HDR) syndrome.@*METHODS@#The child was subjected to genome-wide copy number variation (CNVs) analysis and whole exome sequencing (WES). Clinical data of the patient was analyzed. A literature review was also carried out.@*RESULTS@#The patient, a male neonate, had presented with peculiar facial appearance, simian crease and sacrococcygeal mass. Blood test revealed hypocalcemia, hypoparathyroidism. Hearing test suggested bilateral sensorineural deafness. Doppler ultrasound showed absence of right kidney. Copy number variation sequencing revealed a 12.71 Mb deletion at 10p15.3-p13 (chr10: 105 001_12 815 001) region. WES confirmed haploinsufficiency of the GATA3 gene. With supplement of calcium and vitamin D, the condition of the child has improved.@*CONCLUSION@#The deletion of 10p15.3p13 probably underlay the HDR syndrome in this patient.

HDR syndrome in a Colombian woman with a genital tract malformation: first case report in Latin America / Síndrome HDR en una mujer colombiana con una malformación genitourinaria: primer reporte de caso en Latinoamérica

ABSTRACT Objectives Hypoparathyroidism, sensorineural deafness and renal disease (HDR) syndrome, also known as Barakat syndrome, is an autosomal dominant transmission hereditary disease with a wide range of penetrance and expressivity. Haploinsufficiency of the GATA3 two finger zinc transcription factor is believed to be its cause. This is the first time this orphan disease is reported in Latin America, so the publishing of this report is expected to raise awareness on these types of syndrome, that are usually underdiagnosed in our region, which in turn causes an increase in the years lost to disability (YLDs) rates, as well as higher costs to be assumed by public health systems. Methods A 36-year-old Colombian woman diagnosed with parathyroid gland agenesis was referred from the Endocrinology Service to the Outpatient Service. According to her medical record, in the past she had developed hypocalcaemia, left renal agenesis, hypoparathyroidism, bicornate uterus and sensorineural hearing loss. Through a genetic analysis a pathological mutation on the short arm of the GATA 3 gen (c.404dupC, p Ala136 GlyfsTER 167) was confirmed, which led to a HDR syndrome diagnosis. Discussion This case proves that there is a possibility that mutations described in other continents may be developed by individuals from our region. Regardless of ethnicity, Barakat syndrome should be considered as a possible diagnosis in patients presenting the typical triad that has been described for this condition, since there could be underdiagnosis of this disease in Latin-America due to the lack of knowledge on this condition in said region, and that genetic counseling in these patients is of great importance for the implications of the syndrome in future generations.(AU)

RESUMEN Objetivos El síndrome de hipoparatiroidismo, sordera neurosensorial y displasia renal (HDR) también llamado síndrome de Barakat, es una enfermedad hereditaria de transmisión autosómica dominante con amplia penetrancia y expresividad genética. El síndrome es causado por la haploinsuficiencia del factor de transcripción de dedos de Zinc GATA3. Esta es la primera vez que esta enfermedad huérfana es reportada en latinoamerica, y buscamos generar consciencia de la presencia de estas enfermedades, las cuales usualmente son infradiagnósticadas en nuestro medio y llevan a un aumento de años perdidos por discapacidad y costos para el sistema de salud pública. Métodos Una mujer colombiana de 36 años ingresó a consulta externa de genética referida por el servicio de endocrinología por una agenesia de paratiroides. La paciente tenía antecedentes de hipocalcemia, agenesia renal izquierda, hipoparatiroidismo, sordera neurosensorial y útero bicorneo. Se realizó un análisis genético que confirmo una mutación patológica en el brazo corto del gen GATA3 (c.404dupC, p Ala136 GlyfsTER 167) diagnóstica del síndrome de Barakat. Discusión Este caso demuestra la posibilidad de existencia de mutaciones descritas en otros continentes en nuestra población. Sin importar la etnia, el síndrome de Barakat debe ser estudiado en pacientes que presenten la triada típica, ya que podría existir un infra diagnóstico de la enfermedad secundario al desconocimiento de la misma en Latinoamérica y teniendo en cuenta la importancia que tiene la consejería genética en estos pacientes por las implicaciones de la enfermedad en futuras generaciones.(AU)

The First Korean Case of HDR Syndrome Confirmed by Clinical and Molecular Investigation

Hypoparathyroidism, deafness, and renal dysplasia (HDR) syndrome is a rare condition inherited as autosomal dominant trait and characterized by hypoparathyroidism, sensorineural deafness, and renal dysplasia. HDR syndrome is caused by haploinsufficiency of the GATA3 gene located on chromosome 10p15. Here, we report the case of a 32-day-old Korean male with HDR syndrome. He was presented due to repeated seizures over previous 3 days. The patient was born after 40 weeks of gestation with birth weight of 2930 g, and was the first-born baby of healthy Korean parents. Hypoparathyroidism was first noticed due to seizure. A multicystic left dysplastic kidney and vesicoureteral reflux were detected by ultrasound after birth. Auditory brainstem response (ABR) testing revealed that the patient had moderate sensorineural deafness, with hearing losses of 80 dB at the mid and higher frequencies for both ears. Echocardiography finding revealed secundum atrial septal deftect. Based on biochemical results and clinical findings, a presumptive diagnosis of HDR syndrome was made. GATA3 mutation analysis identified a heterozygous deletion, c.153del (p.Phe51Leufs*144) in exon 1 causing a frameshift mutation, which is a novel de novo mutation. Therefore, we suggest that HDR syndrome should be considered in the differential diagnosis in symptomatic or asymptomatic patients with hypoparathyroidism, and that renal ultrasound or ABR testing be performed to prevent a missed diagnosis. This is the first report on Korean patient with confirmed HDR syndrome with novel mutation.

Hypoparathyroidism-retardation-dysmorphism syndrome.

Congenital hypoparathyroidism, growth retardation and facial dysmorphism is a rare autosomal recessive disorder seen among children born to consanguineous couple of Arab ethnicity. This syndrome is commonly known as Sanjad- Sakati or hypoparathyroidism‑retardation‑dysmorphism syndrome (HRD). We report 13‑year‑old Hindu boy with hypoparathyroidism, tetany, facial dysmorphism and developmental delay, compatible with HRD syndrome.

The calcium-sensing receptor and related diseases / O receptor sensor de cálcio e doenças associadas

The calcium-sensing receptor (CASR) adjusts the extracellular calcium set point regulating PTH secretion and renal calcium excretion. The receptor is expressed in several tissues and is also involved in other cellular functions such as proliferation, differentiation and other hormonal secretion. High extracellular calcium levels activate the receptor resulting in modulation of several signaling pathways depending on the target tissues. Mutations in the CASR gene can result in gain or loss of receptor function. Gain of function mutations are associated to Autossomal dominant hypocalcemia and Bartter syndrome type V, while loss of function mutations are associated to Familial hypocalciuric hypercalcemia and Neonatal severe hyperparathyroidism. More than one hundred mutations were described in this gene. In addition to calcium, the receptor also interacts with several ions and polyamines. The CASR is a potential therapeutic target to treatment of diseases including hyperparathyroidism and osteoporosis, since its interaction with pharmacological compounds results in modulation of PTH secretion.

O receptor sensor de cálcio (CASR) ajusta o set point do cálcio extracelular através da regulação da secreção de PTH e da excreção renal de cálcio. O receptor é expresso em diversos tecidos e também está envolvido em outras funções celulares como proliferação, diferenciação e secreção de outros hormônios. Concentrações altas de cálcio extracelular ativam o receptor resultando em modulação de inúmeras vias de sinais intracelulares dependendo do tecido-alvo. Mutações no gene do CASR podem resultar em ganho ou perda de função do receptor. Mutações com ganho de função são associadas à Hipocalcemia autossômica dominante e à Síndrome de Bartter tipo V, enquanto que mutações com perda de função são associadas à Hipercalcemia hipocalciúrica familiar e ao Hiperparatireoidismo neonatal grave. Mais de cem mutações foram descritas neste gene. Além do cálcio, o receptor também interage com inúmeros íons e poliaminas. CASR é um alvo terapêutico potencial para tratamento de doenças incluindo hiperparatireoidismo e osteoporose, pois a sua interação com compostos farmacológicos resulta em modulação da secreção de PTH.

Sanjad Sakati syndrome [HRD syndrome]

We are reporting two cases with HRD or Sanjad Sakati syndrome from European Gaza Hospital in southern region of Gaza strip - Palestine. They are one boy and one girl from two different families and their parents are consanguineous giving evidence of autosomal recessive inheritance pattern. Both cases are presented with severe hypocalcemic seizures, severe growth retardation and dysmorphic features. Both of them have low parathyroid hormone and renal nephrocalcinosis. None of them has significant cardiac lesion or medullary stenosis in the long bones. Genetic test was not done in both of them because lack of facilities

Extracellular calcium-sensing receptor: structural and functional features and association with diseases

The recently cloned extracellular calcium-sensing receptor (CaR) is a G protein-coupled receptor that plays an essential role in the regulation of extracellular calcium homeostasis. This receptor is expressed in all tissues related to this control (parathyroid glands, thyroid C-cells, kidneys, intestine and bones) and also in tissues with apparently no role in the maintenance of extracellular calcium levels, such as brain, skin and pancreas. The CaR amino acid sequence is compatible with three major domains: a long and hydrophilic aminoterminal extracellular domain, where most of the activating and inactivating mutations described to date are located and where the dimerization process occurs, and the agonist-binding site is located, a hydrophobic transmembrane domain involved in the signal transduction mechanism from the extracellular domain to its respective G protein, and a carboxyterminal intracellular tail, with a well-established role for cell surface CaR expression and for signal transduction. CaR cloning was immediately followed by the association of genetic human diseases with inactivating and activating CaR mutations: familial hypocalciuric hypercalcemia and neonatal severe hyperparathyroidism are caused by CaR-inactivating mutations, whereas autosomal dominant hypoparathyroidism is secondary to CaR-activating mutations. Finally, we will comment on the development of drugs that modulate CaR function by either activating (calcimimetic drugs) or antagonizing it (calcilytic drugs), and on their potential therapeutic implications, such as medical control of specific cases of primary and uremic hyperparathyroidism with calcimimetic drugs and a potential treatment for osteoporosis with a calcilytic drug