Novel compound heterozygous variants in the TAF6 gene in a patient with Alazami-Yuan syndrome:A case report

lNTRODUCTlON

Alazami-Yuan syndrome is an autosomal recessive genetic disease caused by mutation of the TATA-Box Binding Protein Associated Factor 6()gene.Its clinical features are similar to those of Cornelia de Lange syndrome(CdLS).Typical features include short stature,mental retardation,arched eyebrows,conjoined eyebrows,protruding bridge of the nose,nose tilted forward,and a thin upper lip[1,2].There are differences in the gene mutation site and genetic mode between Alazami-Yuan syndrome and CdLS.CdLS is caused by mutations in Nipped-B-like protein(),structural maintenance of chromosomes 1A(),,,and histone deacetylase 8,and the genetic mode is autosomal dominant inheritance and X-linked dominant inheritance[3].

In this case study,two new mutations of thegene were found by high-throughput wholeexosome sequencing in an 11-year-old patient with rapid development of puberty and special facial features.

CASE PRESENTATlON

Chief complaints

An 11-year-old male patient was referred to our clinic due to testicular enlargement and rapid growth in height.

History of present illness

The patient presented with testicular enlargement without obvious cause,no pubic hair,no spermatorrhea,and a small amount of beard hair for 6 mo.Peripheral blood DNA samples obtained from the patient and his parents were sequenced using high-throughput whole-exosome sequencing,which was verified by Sanger sequencing.

History of past illness

The patient was the 2.1 kg(＜ -3sd),46 cm(＜ -1sd),and the product of a 36 wk pre-gnancy born by cesarean section to a gravida 1,para 0-1 mother without a history of asphyxiation and resuscitation.The patient exhibited catch-up growth after birth and no history of feeding difficulties.The physical and mental development of the child at 2-years-old was similar to that of children the same age.

Personal and family history

His non-consanguineous parents were clinically normal.His father and mother were 170 and 151 cm in height,respectively.There was no family history of genetic or infectious diseases.

Physical examination

On physical examination at his visit at 11 years of age,his weight was 52.5 kg and length was 146.1 cm.The patient had a clear mind,good spirit,normal hair,and no yellow coloring or bleeding spots on the skin.He had arched eyebrows,protruding bridge of the nose,forward leaning nostrils,a thin upper lip,a small amount of beard,normal jaw,and an inconspicuous laryngeal knot.Both pupils were equal in size and were sensitive to light.Breath sounds in both lungs were clear,and dry and moist rales were not heard.Heart sounds were strong and regular,the heart rate was 90 bpm,and no pathological murmur was found in each valve area.The abdomen was soft,no tenderness and rebound pain was observed,the liver and spleen were unpalpable.The big toes on both feet were widened and the limbs were normal.Limb muscle tension was normal.Physiological reflexes were present,and pathological reflexes were not found.Bilateral testes were symmetrical,about 8-10 mL in size,without pubic hair.

Laboratory examinations

One sunny day in the early summer, Grandma heard a commotion4（，） in the front yard and looked out the window to see a frightening sight a gigantic5 swarm6 of bees filled the air between two tall trees. There was thousands of bees in the air, so many that the swarm reached the tree-tops!The buzzingsound was tremendous. Grandma watched as the bees made their way into a hole up in one of the trees. Before long, everyone of those bees had disappeard into its new home.

But the old man shook his head sadly, for he knew that the villain35 was only crushed for the moment, and that he would shortly be revenging himself upon them

As he stood on the gallows40 he said: Every one doomed41 to death has the right to speak once before he dies; and I too have that privilege? Yes, said the King, it shall be granted to you

Imaging examinations

The patient underwent a skeletal examination,and the results showed that the bone age was 13 years.Magnetic resonance imaging of the pituitary gland was normal.Slight lateral curvature of the thoracic spine was observed.

High throughput whole-exome sequencing and mitochondrial sequencing

Informed consent was obtained from the parents on behalf of the proband for whole-exome sequencing,mitochondrial sequencing,and the publication of photographs.DNA was obtained from peripheral blood samples from the patient and his parents.Sequencing and analyses were performed by the Beijing Mygenostics(Beijing,China),which is a high-tech biotechnology company providing life science instruments,reagents and technical services.The second generation sequencer Illumina NextSeq500(Illumina,San Diego,CA,United States)was used to sequence the captured region at two ends,with a reading length of 150 bp.After sequencing the target region,the splices and low-quality data in the sequencing data were removed.Using Burrows-Wheeler Aligner software to compare with the reference genome(hg19 version),the data on sequencing depth,homogeneity,and probe specificity were analyzed.Genome Analysis Toolkit software was used to detect the polymorphic sites in the comparison data of each sample,and statistical analyses of the data on single nucleotide polymorphisms(SNPs)and insertion deletion mutations(indels)were conducted.The SNPs and indels were screened using the database of SNPs,(http://www.ncbi.nlm.nih.gov/SNP),1000 human genome(http://www.internationalgenome.org),and the Exome Aggregation Consortium database(http://exac.broadinstitute.org).Application of the human gene mutation database(HGMD,http://www.hgmd.cf.ac.uk)and the human Online Mendelian genetic database(OMIM,http://omim.org)confirmed the reported pathogenic gene locus.The effects of variation on protein structure and pathogenicity were predicted by Rev,Polyphen-2,and Sift.The American College of Medical Genetics and Genomics(ACMG)sequence variation interpretation standards and guidelines[4]were used for a comprehensive evaluation of the pathogenicity of mutation sites.

Gene detection results and pathogenicity analysis

Whole-exome sequencing showed that there was complex heterozygous variation of thegene in this patient,one of which was an unreported frameshift mutation c.1052delT(p.I351Tfs*40),which may lead to the loss of gene function;the frequency of the variation in the normal population database is unknown,and is a low-frequency variation;the results of protein function prediction are unknown,and are not reported in the HGMD database.According to Sanger sequencing,the variation originated from the child’s mother,and the paternal gene was wild-type(Figure 1).According to ACMG guidelines,the mutation was suspected to be pathogenic.

According to the clinical manifestations,laboratory tests,and gene sequencing results,the clinical phenotype of the patient was Alazami-Yuan syndrome.The boy’s weight was above the normal range,and he was given exercise and diet guidance.The patient’s total 25 hydroxy vitamin D level was low,and vitamin D 2000 U was administered once a day for 3 mo,and calcium carbonate 500 mg once a day for 3 mo.To improve the final height of the child,3.75 mg of diphereline was injected once every 28 d,and 10 U recombinant human growth hormone was injected sub-cutaneously every night.

The other was a missense mutation c.76A＞T(p.M26L),which has not been reported.This missense mutation showed 76 nucleotide deficiency changes from adenine to thymine,resulting in the 26 amino acids changing from methionine to leucine.The frequency of the mutation in the normal population database is 0.0014,and is a low-frequency mutation;the results of protein function prediction are unknown,and are not reported in the HGMD database.According to Sanger sequencing,the variation originated from the child’s father,and the maternal gene was wild-type(Figure 1).According to ACMG guidelines,the clinical significance of the variation is unknown.

The patient’s liver function,kidney function,electrolytes,blood glucose and blood lipids were normal.Insulin-like growth factor was normal.Karyotype analysis of cultured cells revealed a karyotype of 46XY.Sex hormone levels were as follows:estradiol 25 pg/mL,(adult male reference value:＜ 20-47 pg/mL),follicle-stimulating hormone 6.62 mIU/mL(adult male reference value:1.27-19.26 mIU/mL),luteinizing hormone 3.20 mIU/mL(adult male reference value:1.24-8.62 mIU/mL),and testosterone 1.75 ng/mL(adult male reference value:1.75-7.81 ng/mL).Total 25 hydroxy vitamin D was 13.79 ng/mL(reference value ＜ 20 ng/mL vitamin D deficiency).Fasting insulin was 23.1 mU/L(reference value:2.3-11.8 mU/L).Thyroid function was evaluated as follows:Triiodothyronine 6.84 pmol/L(reference value:2.63-5.71 pmol/L),thyroxine 12.10 pmol/L(reference value:9.01-19.05 pmol/L),and thyroid-stimulating hormone 1.9145 μIU/mL(reference value:0.30-4.80 μIU/mL).

FlNAL DlAGNOSlS

Sanger sequencing showed that there was a compound heterozygous mutation of c.1052delT and c.76A＞T in thegene.

Grampy stretched his long leg out straight and reached his huge hand deep into the pocket. I could hear the familiar jangling（） of the loose change he always carried. Opening his fist, he exposed a mound8 of silver coins. There must have been a million dollars there. He instructed me to pick out a dime9. After he deposited the rest of the change back into his pocket, he stood up.

TREATMENT

One of the main twelve themes of my happiness project is marriage. For me, as with many people, my marriage is one of the most central elements in my life and my happiness. When I started my happiness project, and I reflected about the changes I wanted to make -- as well as the resolutions（，） I wanted to keep in order to bring about those changes -- I realized I had five particular problem areas in my marriage.

OUTCOME AND FOLLOW-UP

After 4 mo of treatment,the child’s height increased by 3.6 cm,his weight decreased by 0.7 kg,and the vitamin D level returned to normal.During treatment,skin at the injection site was good,fasting blood glucose and nail function were normal,and there was no eyelid edema,headache,or other adverse reactions.

DlSCUSSlON

Thegene is located on chromosome 7q22.1,which is involved in the initiation and activation of RNA transcription and is closely related to human cell viability[5].The mutation ofgene can lead to Alazami-Yuan syndrome.In published cases,5 patients from two families have been reported.Their parents were consanguineous,and the mutation types were homozygous mutations,with mutation locations at c.136c＞T and c.212t＞C[1,2].The clinical manifestations of these patients were similar,with short stature,mental retardation,and typical facial features of CdLS.We report a case of compound heterozygous mutation in which the parents were non-consanguineous and the mutation location was c.1052delT and c.76A＞T.The main clinical manifestations were rapid puberty and special body surface characteristics,including arched eyebrows,protruding nose bridge,forward leaning nose,thin upper lip and widened big toes on both feet.The child had normal intelligence and was born small for gestational age,but had no history of feeding difficulties.Growth and development before puberty were basically normal.

Informed consent has been obtained from the patient and her family for all information mentioned in this report.

The patient first attended hospital due to enlarged testicles for 6 mo.His bone age was 2 years older than his actual age,and puberty developed rapidly.In order to improve the final height of this patient,he was treated with the combination of diphereline and recombinant human growth hormone.The patient's special facial features were similar to those of CdLS which attracted our attention at his first visit,but the patient had no mental retardation or language deficiency.In order to determine the cause of the disease,we used high-throughput whole-exome sequencing and identified a compound heterozygous mutation of thegene.Most patients with CdLS have new mutations,and the risk of their parents having another CdLS child is low.In this case,the two mutated genes were from the father and mother,respectively.The probability of the parents having a child with Alazami-Yuan syndrome was 25%,and the probability of carrying the pathogenic gene in a subsequent child was 50%.It is suggested that prenatal consultation and diagnosis should be carried out if the child's mother has subsequent pregnancies.

CONCLUSlON

The authors have read the CARE Checklist(2016),and the manuscript was prepared and revised according to the CARE Checklist(2016).

ACKNOWLEDGEMENTS

We would like to thank the child and his family members for agreeing to participate in this study.

FOOTNOTES

Lin SZ and Feng JH collected and analyzed all clinical data and wrote the manuscript;Sun LP participated in collation of the literature and the chart research;Ma HW was involved in the genetic diagnosis and treatment of the patients;Lin SZ,JF,Wang WQ,and Li JY substantially participated in drafting and revising the manuscript for important intellectual content;all authors involved have read and approved the final manuscript.

Natural Science Foundation of Jilin Province,No.20200201486JC.

CdLS(OMIM:122470)is a type of multiple congenital dysplasia.Patients usually have physiological,cognitive and behavioral characteristics[6].According to previous case reports,CdLS1 caused by gene mutation ofaccounts for about 50% to 60% of CdLS cases[7].A large number of individuals with typical CdLS carry a mosaicvariation[8].Although individuals with typical CdLS phenotypes are likely to have mutations in,individuals with one of the other pathogenic CdLS genes can also meet the standard for typical CdLS[9-14].Typical CdLS has a unique craniofacial appearance and growth pattern,as well as limb deformities.However,not all CdLS patients show typical phenotypes,and there are differences in the manifestations of the disease itself,from mild to severe,and the degree of facial and limb involvement is also different[15].In this report,although the patient had typical facial features of CdLS,he had a unique clinical phenotype and gene mutation sites,which has practical significance for in-depth research and clinical guidance.

All the authors of this article have stated that there is no conflict of interest and have signed the relevant documents.

Herein,the rapid development of puberty and older bone age were defined for the first time in the-related phenotype.We suggest thatshould be considered in individuals with rapid development of puberty and CdLS-overlapping features.Furthermore,our patient was found to be a compound heterozygote for two novel pathogenic variants in.Identification of a compound heterozygote should encourage clinicians to consider Alazami-Yuan syndrome in patients with similar clinical features and without a family history of consanguinity.

This article is an open-access article that was selected by an in-house editor and fully peer-reviewed by external reviewers.It is distributed in accordance with the Creative Commons Attribution NonCommercial(CC BYNC 4.0)license,which permits others to distribute,remix,adapt,build upon this work non-commercially,and license their derivative works on different terms,provided the original work is properly cited and the use is noncommercial.See:https://creativecommons.org/Licenses/by-nc/4.0/

But now the Fairies who had been watching all these proceedings with interest, thought it was time to interfere138, and ascertain139 by further trials if this improvement was likely to continue, and if they really loved one another

China

For a long time he kept silence about it; but one day, when he had been complaining of her absence, she said to him: Dear husband, I am bound to go, even against my will, and there is only one way to stop me

Shuang-Zhu Lin 0000-0001-5333-2138;Jin-Hua Feng 0000-0002-2911-0022;Li-Ping Sun 0000-0002-3679-4469;Hong-Wei Ma 0000-0001-8678-5811;Wan-Qi Wang 0000-0002-8247-7616;Jia-Yi Li 0000-0002-7729-4479.

Liu JH

Filipodia

1872FAIRY TALES OF HANS CHRISTIAN1 ANDERSENA LEAF FROM HEAVENby Hans Christian AndersenHIGH up in the clear, pure air flew an angel, with a flowerplucked from the garden of heaven. As he was kissing the flower a very little leaf fell from it and sunk down into the soft earth in themiddle of a wood. It immediately took root, sprouted2, and sent outshoots among the other plants. What a ridiculous little shoot! said one. No one will recognize it; not even the thistle nor the stinging-nettle. It must be a kind of garden plant, said another; and so theysneered and despised the plant as a thing from a garden. Where are you coming? said the tall thistles whose leaves were all armed with thorns. It is stupid nonsense to allow yourself to shoot out in this way; we are not here to support you.

Liu JH